TABLE OF CONTENTS Acknowledgement Introduction General ...

TABLE OF CONTENTS 

Acknowledgement 

Introduction 

General Issues and Principles 

Participatory Approaches and Extension 

Strategies 

Community-Managed Aquatic Resources 

Freshwater Systems/Terrestrial Systems 

Lake and Reservoir-Based Systems 

Brackishwater and Marine Systems 

Participants 

Advisory Committe 

Production Staff 

Correct citation

Utilizing Different Aquatic Resources for Livelihoods in Asia 

Acknowledgement 

We gratefully acknowledge the valuable and generous financial and technical 

support of our partners, advisory committee members, workshop participants and 

production staff. 

Partners 

International Development Research Centre 

Food and Agriculture Organization of the United Nations 

Network of Aquaculture Centers in Asia-Pacific 

International Center for Living Aquatic Resources Management 

Asian Institute of Technology - Aquaculture Outreach Program 

The Netherlands Embassy - Manila, Philippines 

German Agro Action 

Southeast Asian Fisheries Development Center 

International Institute of Rural Reconstruction 

Advisory Committee 

Joy Rivaca-Caminade 

Harvey Demaine 

Julian F. Gonsalves 

Matthias Halwart 

Dilip Kumar 

S. S. Tabrez Nasar 

Gary F. Newkirk 

Rolando Platon 

Mark Prein 

Workshop Participants 

A.K.M. Reshad Alam 

Warlito C. Antonio 

S. Ayyappan 

Ian G. Baird 

Zubaida U. Basiao 

Arsenia Cagauan 

Barry Clough 

Fernando B. Dalangin 


K. Devadasan 

Nguyen Huy Dien 

Christie Fernando 

Luis Maria B. Garcia 

Wenresti G. Gallardo 

John H. Grover 


Nazmul Hassan 

Khorkiat Koolkaew 

Contributors 

Li Kangmin Miao Weimin 

José Aguilar-Manjarrez 

Editors 

Carlos William W. Azucena 

Bernadette P. Joven 

Dilip Kumar 

Felix Marttin 

M.C. Nandeesha 


Julia Lynne Overton 

Elena Z. Par 

Jurgenne Primavera 

Mark Prein 

R.K.U.D. Pushpa Kumara 

Tran Van Quynh 

Mokhlesur Rahman 

Alejandro E. Santiago 

P.P.G.S.N. Siriwardena 

V. V. Sugunan 

Wilfredo G. Yap 

Yang Yi 

Xiaowei Zhou

Siobhan O’Malley 

Ma. Stella S. Oliver 

Mayla Hernandez Viray 

Artists 

Ariel Lucerna 

Carlito N. Bibal 

Jonas Diego 

Rey Cuevas 

Ric E. Cantada 

Rollie N. Nicart 

Desktop Publishing Staff 

Celso Amutan 

Hannah K. Castaneda 

Ivan Roy Mallari 

Evangeline C. Montoya 

Jeffrey T. Oliver 

Administrative/Logistics Staff 

Annex Costa 

Ronnie De Castro 

Ma. Aida Gaerlan 

Marlon Manila


Introduction 

The search for sustainable, livelihood approaches to reduce poverty continues to 

pose a challenge to rural development planners and practitioners. Often this is 

because of the very nature of poverty itself, which remains complex: the very poor 

are vulnerable to an interplay of a rather wide range of forces and factors. However, 

natural resources, especially water resources, continue to be available to poor 

families in many parts of the world and poor families have demonstrated that they 

can utilize these resources in a sustainable manner. Farmers, the landless and fishers 

all over the world, continue to face (and often overcome) the challenges of poverty 

by developing their water-based, natural-capital stocks. They often do it using 

human capacity and the social capital available locally. Development agencies too 

have attempted to add value to these efforts by undertaking research and 

development efforts that build on these initiatives. Success stories are abundant 

especially in Asia. But mistakes have also been made, resulting in the destruction of 

these very assets that could help alleviate poverty. New programs can benefit from 

these experiences as lessons are now readily available for wider sharing. 

How this resource book was produced 

This resource book consists of a 

compilation of proven experiences 

(from Asia) that are totally field-derived. 

This book is the result of the 

participatory workshop process 

conducted on September 18-28, 2000 

at the International Institute of Rural 

Reconstruction (IIRR), Y. C. James Yen 

Center, Silang, Cavite, Philippines. Thirtyseven 

participants from 12 countries 

worked closely with a production team 

of editors, artists and desktop publishing 

staff. 

Prior to the workshop, an initial list of topics was developed by the steering 

committee. A set of guidelines for developing the first draft papers was drafted and 

sent to the participants. 

During the workshop, each participant presented his or her first draft, using overhead 

transparencies of each page. Copies of the draft papers were also provided to all 

other participants who critiqued the draft and suggested revisions. 

After the first presentation, an editor-artist team helped the author revise and edit 

the draft and draw illustrations to accompany the text. The edited draft and artwork 

were then desktop published to produce a second draft. 

Each participant then presented his or her revised draft to the group for the second 

time, also using transparencies. Again, the audience critiqued it and suggested 

revisions. After the presentation, the editors, artists and desktop publishing staff again 

helped the author revise the material and develop the third draft. At the end of the 

workshop, the drafts were put on display for review and sign off by the authors. 

Throughout the workshop, the participants worked together in informal groups to 

discuss and improve the manuscripts. Although the principal authors are listed on 

each paper in this resource book, all the papers benefitted from a critical review by 

workshop participants. 

After the workshop, a semi-final draft was reviewed by the advisory committee 

members (Dr. Harvey Demaine, Dr. Julian F. Gonsalves, Dr. Matthias Halwart, Dr. Dilip

Kumar, Dr. S. S. Tabrez Nasar, Dr. Gary F. Newkirk, Dr. Rolando Platon and Dr. Mark 

Prein). The publication was managed and coordinated by an IIRR team: Dr. Tabrez 

Nasar, Ms. Joy Caminade, Ms. Jel Montoya and Dr. Julian Gonsalves. Jel Montoya 

and Mr. Jeffrey Oliver coordinated the final publishing of the manuscript. 

The workshop design and subsequent 

reviews benefited greatly from inputs 

from members of the advisory 

committee. However special mention 

must be made of a few individuals who 

provided strategic inputs during the 

entire process. Without their inputs this 

publication would not have been 

realized: Dr. Gary Newkirk of Dalhousie 

University/International Development 

Research Centre (IDRC), Dr. Mark Prein 

of International Center for Living 

Aquatic Resources Management 

(ICLARM), Dr. Matthias Halwart of Food 

and Agriculture Organization of the 

United Nations (FAO), Dr. Dilip Kumar formerly of Network of Aquaculture Centers in 

Asia-Pacific (NACA), (now with FAO-RAPA) and Dr. Pedro Bueno (NACA). 

Very special acknowledgments are due to Dr. Gary Newkirk of IDRC/Dalhousie 

University, Dr. John Graham, Dr. Brian Davy and Dr. Stephen Tyler of IDRC and Ms. 

Eva Marischen and Mr. Stephan Jansen of German Agro Action (GAA) who saw 

value in this effort, right at the outset. They encouraged the original proponents from 

IIRR, Dr. Julian Gonsalves and Dr. Tabrez Nasar through the difficult two years, when it 

appeared as though additional funding might not be available from other donors. 

Fortunately FAO, NACA and the Netherlands Embassy came in at the critical stage 

with the absolutely essential, supplementary- funding inputs. Special mention must 

be made of Ms. Elsa da Costa and Mr. Maurits ter Kuile of the Dutch Embassy who 

responded positively to a request for supplementary funding, made only a few 

weeks prior to the initiation of the workshop. With partners like Southeast Asian 

Fisheries Development Center (SEAFDEC), the Asian Institute of Technology (AIT) 

Aquaculture Outreach Program, ICLARM, FAO and NACA, we are sure that these 

materials will get disseminated and used with relevant audiences. 

This resource book is complementary to the publication produced in 1992 (IIRR and 

ICLARM. 1992. Farmer-Proven Integrated Agriculture-Aquaculture: A Technology 

Information Kit) which focused mainly on lowland freshwater systems and has been 

published in revised form by FAO in 2001 (FAO/ICLARM/IIRR 2001. Integrated 

Aquaculture: A Primer. FAO Fisheries Technical Paper No. 407. Rome, FAO. 149p). 

Comments were made during the workshops 

that many aquaculture conferences and 

meetings do not provide enough of an 

opportunity for healthy and constructive critique 

of ideas. This publication intentionally presents a 

diversity of perspectives and positions. The views 

presented remain those of the authors (whose 

names appear at the end of each article). The 

fact that the reader is presented with a diversity 

of viewpoints and perspectives make portions of 

this resource book of relevance to a wider range of development practitioners, local 

government officials and academic institutions. Addresses are provided for readers 

to contact the authors directly. Special consideration is given to the need for an 

integrated conservation-development perspective. This resource book presents, in a 

single compilation, information on how a wide range of aquatic ecosystems are 

utilized. Poor people’s livelihoods, based on aquaculture are characterized by 

diversity and it is important therefore, to understand landscapes and sub-ecosystem 

linkages. The role that fresh, brackish and coastal water systems (and various other 

systems in between) can play in people’s livelihoods in Asia is discussed (as it relates 

to aquaculture). Household food security, nutrition, income generation, the need for 

conserving the resource base and gender considerations were constantly 

considered during the workshop, as materials were recast and repackaged.

Conflicts in resource use by various stakeholders, often engaged in different forms of 

water-based livelihoods are discussed by many individual authors. These are lessons 

from the field and are shared so future action is influenced. These perspectives show 

up in most articles. 

The partners in this documentation effort encourage wide use of these materials. 

There is no copyright. Feel free to use the materials in advocacy, training, planning 

and field-support work. Consider using in newsletters and newspapers (including 

presenting the materials in serialized forms) after acknowledging the original authors 

and the co-publishers of the resource book. We all realize the value and need for 

upscaling our efforts in small scale aquaculture: this publication could potentially 

feature prominently in any effort to broaden the opportunities for improved 

livelihoods for the poor, based on the careful use of aquatic resources.


General Issues and Principles 

The Role of Small-Scale 

Aquaculture in Rural 

Development 

Aquatic Resources 

Management for Sustainable 

Livelihoods of Poor People 

Social and Cultural 

Considerations in Small-Scale 

Aquaculture 

Socio-Economic Impact of 

Rural Pond Fish Culture 

Involvement of Women in 

Small-Scale Aquaculture 

Impact of Aquaculture on the 

Environment 

Conservation of Aquatic 

Genetic Diversity 

Development Assistance for 


Introducing Aquaculture into 

Farming Systems: What to 

Look Out For 

Importance of Fish in 

Household Nutrition 

Managing the Introduction of 

Exotic Species 

Primary Health Care in 

Aquaculture 

Fish as Biocontrol Agents of 

Vectors and Pests of Medical 

and Agricultural Importance 

Possible Public Health 

Hazards Associated with 

Farmed Fish and Shellfish 

Improved Handling and 

Quality Assurance of Fish and 

Fishery Products 

General Issues and Principles

The Role of Small-Scale Aquaculture in Rural 

Development 

Poverty alleviation is central to the concept of rural development. 

However, the prevailing development strategy in the 1960s and 1970s of 

structural change based on urban-industrial growth did not lead to the 

trickle-down of benefits to poor people in rural areas. “Rural 

development” approaches, thus, emerged to address more directly the 

problem of rural poverty. 

Different approaches to rural development 

Basic minimum needs provision, implying a continuation of 

paternalistic attitudes by government 

Integrated rural development, emphasizing the need to address 

both the economic and social issues 

Employment creation, emphasizing the economic sector 

Key principles emerging 

Peoples’ participation 

Bottom-up planning 

This has been just as true of aquaculture as with other sectors. After 

concentrating on intensive systems based on high-external input

technologies in the last decade, significant attention has begun to be 

paid to rural aquaculture, a portfolio of technologies which are 

specifically oriented to address the needs of the poor people. 

Poverty, however, is complex and poor rural people do not rely for their 

livelihood on the agricultural sector alone. This perception has led in 

recent years to the emergence of “sustainable rural livelihoods” as an 

approach for the analysis of poverty and possible intervention for its 

alleviation. This approach examines the position of rural households in 

relation to the availability of various capital assets. 

Assets 

● Natural capital: access to land, water, forests and 

other resources 

● Physical capital: presence of roads, irrigation systems, 

schools and other important economic and social 

infrastructure 

● Human capital: available labor and skills, experience 

and education of the rural household 

● Financial capital: investment resources available to 

the household, whether from their own savings or the presence of 

credit systems 

● Social capital: namely the networks which may be tapped to 

support the individual household. Support may come from informal 

associations within the village community or from formal institutions 

at local, sub-regional and even national level.

Factors affecting the basic assets 

Vulnerability forces 

These forces may include sudden shocks in the physical environment 

such as drought, flood or typhoons, or longer term trends in the 

economic environment and resource stocks. Both of these can reduce 

the assets normally available to the household. 

Transforming structures and processes 

Transforming structure and processes refers to the nature and operation 

of the institutional environment, encompassing public and private 

institutions, laws, policies which can work positively or negatively to 

affect access to capital and maintenance of it (Carney, 1999). It is in 

response to their asset situation, in the context of the various 

vulnerability factors and the prevailing structure and processes, that the 

rural poor develop their livelihood strategies. 

The challenge for aquaculture is whether it can help strengthen the 

assets available to rural households so that they are better able to

withstand shocks, become less vulnerable and are better able to 

influence the policy/institutional environment in their favor. We now 

examine whether aquaculture is able to do this. 

Potential roles and impacts of aquaculture on poverty and rural livelihoods 

Aquaculture may assist poor rural households by 

enhancing their natural capital stocks. In relation to 

natural capital, rural people may be poor because: 

l they lack such capital assets (for example land, in 

the case of the landless); 

l the scale and quality of their natural capital (the 

context of small-scale farmers in resource-poor 

environments) are limited; and 

l the natural capital on which they depend has been 

degraded (for example in the case of fishers 

previously dependent on catches from either the 

freshwater or the marine environment). 

By creating, adding value to or restoring natural capital, aquaculture 

may contribute to the livelihoods of poor households directly involved in 

the enterprise. The underlying benefits of direct involvement would be 

improved food security, creation of employment opportunities and 

income generation. In addition, aquaculture may improve the 

sustainability of other farm enterprises. 

For those with land, where pond aquaculture is practiced 

The pond offers an extra source of water to help offset the effects of 

drought on staple crops and provide water for vegetables and fruit. This 

is particularly the case in areas of resource-poor agriculture, which is 

dependent on erratic rainfall. 

Where aquaculture is practiced in paddy fields 

The incorporation of fish in the system can both improve rice yields and 

reduce costs of production. 

For the landless 

Common property resources may provide an opportunity for 

aquaculture provided that villagers have the social capital to secure

access to the resources and eventually enhance them. In these cases, 

aquaculture becomes an entry point for building up other assets. 

For fishers 

Aquaculture may help to replace the livelihood lost through overfishing 

or environmental destruction. In order to ensure a sustainable operation, 

the need for major investment in physical capital is recognized. 

Indirect benefits from aquaculture 

● Reducing the cost of fish to rural consumers 

● Creating wage employment on larger farms or in fish products 

processing 

● Cheap fish for urban consumers 

Barriers to entry of aquaculture 

The high investment 

required in the creation 

of physical capital for 

aquaculture such as 

pond, trench or cage, 

the excavation, etc., 

might not seem 

affordable. Additionally, 

the costs of fish seed, 

feed and/or fertilizers 

and harvesting 

equipment have to be 

considered. 

In fact, the investment 

costs are rarely as high as might be assumed, especially in traditional 

rice-fish societies, so that access to aquaculture is well within the existing 

financial and social capital stocks of the farmer. 

In order to provide human settlement in low-lying lands in flood plains,

ponds are excavated in order to use the soil as a platform for the 

homestead to raise it above the flood. 

This automatically gives the 

household at least a small pond close 

to the house. Aquaculture frequently 

develops as the pressure on the 

existing rice-field fishery increases. To 

attract wild fish to their particular part 

of the paddy, farmers dig small pits or 

ponds which act as sumps as the 

water recedes trapping the fish. These 

“trap ponds” may be widened and deepened as the farmer becomes 

more oriented to aquaculture. 

While these traditional practices form a low-cost basis for the 

development of aquaculture, so do development projects. 

Construction activities usually require excavation of soil for landfill 

elsewhere and farmers may find themselves being given an opportunity 

for free pond excavation as a result. Evidence from Bangladesh 

demonstrates that even burrow pits and on-farm ditches can be a 

resource for the landless, especially with the introduction of tilapia 

culture which offers the opportunity of sale of swim-up fry after just a few 

months. 

In traditional rice-fish culture in upland areas in the Lao PDR and 

Vietnam, these ponds may be used to stock broodfish 

throughout the winter season, allowing farmers to produce their 

own seed locally and to reduce dependence on more 

expensive, imported supplies.

At present, development projects recognize that the farm pond is a key 

element in the creation of physical/natural capital for poor households, 

thus, offering free or subsidized services for pond construction. Whether 

this is seen as a fish pond or not, fish culture usually adds value to the 

resource unless it is also to be used for drinking water supply (as was the 

constraint in the Family Food Production Project, an early attempt to 

promote aquaculture in Cambodia). 

These issues only relate to land-based 

systems. For the rural poor, often 

landless, open access or common 

property aquatic resources may offer 

access to aquaculture: 

Freshwater context 

Resources may include backswamps 

and oxbows in flood plain 

environments or small reservoirs, 

including watershed catchments in 

small tributary valleys. 

Coastal areas 

Where many coastal fishers have been suffering from reduced catches 

in recent years, sheltered estuaries and bays constitute potential 

resources. The big issue in these cases is whether the rural poor can 

secure permanent access to the use of the water bodies concerned, 

i.e., whether existing power structures and processes in the community 

facilitate this access. 

Another constraint to coastal aquaculture is the openness of the area. 

With open access to coastal areas, individuals have difficulty obtaining 

tenure and even communities may not have jurisdiction. Even when 

they do have jurisdiction, their ability to enforce control is constrained 

by the physical openness of the sea. 

Technical options for small-scale aquaculture

Many opportunities await the rural poor people when they take part in 

this enterprise without major capital investment. The issue centers on 

availability of suitable technology for fish culture and if this technology is 

accessible to poor people. Aquaculture technology is perceived to be 

either physically inaccessible or too risky for many rural poor people. 

However, these were based on conventional approaches that are now 

being superseded. 

Two main stages in aquaculture production 

1. Seed production 

Supply of quality seed is fundamental to developing the enterprise. 

Apparently, many areas are characterized by inadequate seed supply 

despite the widespread development of large-scale hatcheries, often 

with donor funding. However, hatchery facilities have been 

decentralized and small farmers in rural areas can even produce their 

own seed without conventional hatcheries. 

For many estuarine and marine species, natural sources of seed with 

acceptable reliability are abundant. Wild seed is currently the only 

acceptable economic option for oysters, mussels and clams. For other 

marine species, there is sufficient wild seed for small-scale production, 

although this begins to be an issue as the area of culture expands. 

Farmers in the highland valleys of Vietnam and the Lao PDR have traditionally 

spawned fish (e.g., common carp in paddy fields). Such systems remain common 

in more developed areas in Indonesia and China. Small carps and tilapias can be 

bred locally in pond culture, which not only reduces costs and improves quality – 

since long-distance transportation is no longer needed – but also provides 

employment and income for small-scale farmers. Those with slightly better water 

resources are able to breed fish, while others can nurse fish in cheap nylon cages 

for onward sale. Such systems have been developed in Bangladesh, Cambodia 

and the Lao PDR where they have had a powerful multiplier effect (Edwards, 2000 

and RDC, 2000). 

2. Grow-out stage 

Aquaculture may be practiced in a wide variety of options. The

technologies, which offer valuable livelihood options to the rural poor, 

are available. These center around herbivorous and omnivorous 

species, which can thrive on various on-farm fertilizers and feeds and 

inputs that can be gathered from the wider resource system. Several 

systems of fish culture are based gathered grasses and other 

vegetation. 

Other systems depend on fertilization strategies using animal manures. 

Some cultural constraints exist in the use of manures as well as limitations 

in the nature of the agricultural system, particularly where livestock are 

not penned. However, the culture of some improved species of Nile 

tilapia by the rural poor, with only limited applications of inorganic 

fertilizer, also has been successful. 

Coastal aquaculture 

In northern Vietnam, aquaculture systems have centered on 

grass carp for the last 40 years since its introduction from 

China. This species is reared in both ponds and cages, fed with 

grasses, maize residues and cassava leaves. In the south of 

Vietnam, an equivalent "poor person’s system" based on giant 

gourami, which also feeds on vegetable matter (although 

growth rate is a constraint), exists. 

In southern Vietnam, the culture of pangasius catfish (Pangasius hypophthalmus), 

reared in overhung latrine ponds, is a second low-cost system. These grow quickly 

without purchased inputs and can be the basis of a more diversified system. 

More work has been done in freshwater aquaculture than in coastal 

aquaculture in developing production systems suitable for poor people. 

The culture of mollusks and seaweeds appears to have high potential, 

while requiring only minimal investment. These water-based systems do 

require some investment in order to develop aquaculture but, at least 

initially, cages and poles for shellfish culture can be made from relatively 

cheap and locally available materials like bamboo. 

Most coastal aquaculture technology, however, has been aimed at 

moderately high to high-value species. These species are too expensive 

for household consumption of the poor people and low-cost culture 

systems for these species are rare. The culture of high-value species

entails more investment for crop security, either for physical 

confinement or protection from theft. Aside from the financial 

constraint, it is questionable whether poor people would undertake 

such risk-prone activities. 

Conclusion 

Aquaculture is more accessible to poor rural people than has been 

generally realized and a range of technological options now exists. 

However, much remains to be done. 

● It is important that efforts in 

research and development 

continue to be focused upon 

the sorts of technical options 

that were described, 

particularly in coastal areas. 

● National governments must 

be committed to providing an 

environment which allows 

poor people access to 

productive assets and 

resources, possibly through 

specifically targeted support 

packages. 

● Strategies will often require 

major changes in policy and in attitude among government 

departments and individuals. 

● Finally, bearing in mind the sustainable rural livelihood approach, 

the participation of the rural poor in aquaculture will depend on a 

whole range of social and economic factors at the farm, 

community and regional/national levels. In a more general context, 

these factors may include the key economic issue of relative 

“catch per unit effort” to be obtained. In the narrow sense, this 

involves assessment of the merits of aquaculture compared to 

capture fisheries and assessment of other alternative livelihood 

opportunities, both on and off farm.

References 

Carney, Diana. 1998. Sustainable Rural Livelihoods: What 

Contributions Can We Make. DFID, London. 

Carney, Diana. 1999. Approaches to Sustainable Livelihoods, ODI 

Poverty Brief 2. January 1999. 

Edwards, Peter and H. Demaine. 1997. Rural Aquaculture: Overview 

and Framework for Country Reviews. FAO/RAP, Bangkok. 

Edwards, Peter. 2000. Aquaculture, Poverty Impacts and Livelihoods. 

Natural Resource Perspectives, Number 56, June 2000. ODI, London. 

Pham Anh Tuan, D. Little, A. Nietes-Satapornvanit, P. Edwards, N. T. T. 

Linh and M. Jones. 2000. Fish Seed Quality in Northern Vietnam. State 

of the System Report. AIT Aquaculture Outreach, Asian Institute of 

Technology, Bangkok, Thailand. 

Regional Development Committee (RDC). 2000. The Nursing Network. 

Poster submitted to the DFID Aquatic Resources Management 

Programme E-mail Conference on Aquatic Resources Management 

for Sustainable Livelihoods of Poor People. 

Tu, Nguyen Van, D. Little and A. Nietes-Satapornvanit. 2000. Fish Seed 

Quality in Southern Vietnam. State of the System Report. AIT 

Aquaculture Outreach, Asian Institute of Technology, Bangkok, 

Thailand.

Aquatic Resources Management for Sustainable 

Livelihoods of Poor People 

The role of aquatic resources in poor peoples’ livelihoods is complex and context 

specific. Aquatic resources management in the context of poverty is not limited to 

technology or forms of aquaculture but could include improved access to natural 

stocks of fish and other aquatic organisms. Policies, institutions and processes that 

support livelihood strategies involving aquatic resources are also important. In the 

past, there has been a failure to recognize the contribution of aquatic resources 

management to food security for the rural poor. The livelihoods of the poor, in fact, 

can be adversely affected by policies and practices in other sectors (especially 

agriculture and water management) that undervalue aquatic resources. For 

example, some forms of irrigated agriculture (weir and dam schemes) have had 

negative impacts. 

Aquatic resource diversity 

Temperate/Tropical 

Inland Coastal

Riverine 

Rivers 

Floodplains 

Irrigation channels 

Lacustrine 

Lakes 

Reservoirs 

Ponds 

Palustrine 

Swamps 

Rice fields 

Estuaries 

Lagoons 

Coral reefs 

Mangroves 

Mudflats 

Ponds 

Livelihoods based on aquatic resources are characterized by diversity of resources, 

environments, resource users and the ways people exploit resources and 

incorporate them into their livelihoods. 

It is difficult to assess aquatic resource use by poor people. The complexity of 

seasonally and spatially variable environments and stakeholder activities often 

results in incorrect resource use estimates. Good case-study evidence may provide 

more valuable information. The social context is especially important, particularly 

access arrangements and the assessment of benefits to livelihoods. 

Technical issues and lack of new knowledge are not major constraints to 

aquaculture development. There is a wealth of knowledge, including local 

knowledge, that only needs effective widespread dissemination to 

enhance human capital. People, not ponds or technology, are the entry 

point for aquaculture development. There has been a positive shift from 

technology-led production-oriented project interventions to a people-first 

sustainable livelihood approach. Poverty and environment degradation 

can be eliminated through holistic development interventions that 

facilitate diversified sustainable livelihoods. 

Available statistics on aquatic resource use do not reflect reality well: they 

commonly under or over estimate the resource. Little information is given on 

seasonality and markets. 

Well collected and presented information on the value of aquatic resources to poor 

people empowers users and their advocates. Such information is less easily ignored 

by competing sectors. 

Evidence of the role of aquatic resources in poor peoples’ 

livelihoods

In some parts of Southeast Asia, aquatic resources constitute a large share of the 

animal protein intake of poor households. Households catch and consume 

significant quantities of fish and other aquatic products. But there is increasing 

evidence that wild aquatic resources are declining. 

What general evidence is available on the role of aquatic resources in the 

livelihoods of poorer groups? For those working in the field, the role of aquatic 

resources in poor peoples’ livelihoods is self-evident. However, policy makers need 

hard evidence for formulating more pro-poor policies or to make resource allocation 

decisions. Evidence can play a role in supporting planning and legislation and 

improving the institutional context of decision-making. Greater emphasis on 

advocacy (outside the sub-sector) is required to raise awareness of the role for 

aquatic resources management in rural development and to bring about desirable 

institutional changes. 

The role of aquatic resources in food security of poor households in Southeast Asia 

The role of 

aquatic 

resources in the 

diet 

Fish production/ 

consumption 

estimates 

NE Thailand Cambodia Lao PDR Vietnam 

72-82% of animal 

protein 

consumed in the 

wet season in 

Yasothon 

Province 

comprises wild 

aquatic 

resources, 

derived from rice 

fields. 

Average 

consumption for 

northeast 

Thailand 30-34 

kg/cap/y 

according to 

three 

independent 

studies. Fish 

availability in the 

hungry season is 

highly valued. 

Fish and fish 

products 

account for 70- 

75% of the dietary 

protein intake of 

the population of 

Cambodia. 

Average 

consumption 

28-41 kg/cap/y. 

However, eight 

provinces around 

the great lake 

and the Mekong 

(population 4.1 

million out of a 

national 

population of 

10.5 million) 

household 

sample surveys 

suggest the 

Fish had 

traditionally 

contributed 85% 

of animal protein 

intake. A recent 

survey in Luang 

Prabang Province 

found fish to 

represent 50-55% 

of animal protein 

intake. Fish still 

represents the 

largest 

component of 

animal protein in 

the diet. 

Average 

consumption 11- 

22 kg/cap/y in 

poor villages in 

Savannakhet 

Province. In some 

parts of Luang 

Prabang Province 

in the north, per 

capita 

consumption is 

22 kg/y. 

Some small water 

Fish in An Giang 

Province 

contributes nearly 

76% of the 

average person’s 

supply of animal 

protein. The role 

of aquatic 

resource in the 

diet of northern 

provinces is much 

less. 

Production and 

consumption is 

greater in the 

south than in the 

north. In the 

northern 

mountains, 

several kg/cap/y 

is common. In the 

south, e.g., Long 

An Province, 

farmers catch 

531 kg/hh/y; and 

average fish 

consumption is 60

Current trends 

availability 

In northeast 

Thailand there 

has been a 

steady decline in 

natural fish catch 

over the last six 

years in all water 

resources. 

Availability is 

strongly 

correlated with 

rainfall. 

consumption of 

fish and 

processed fish to 

be at least 

67 kg/cap/y. 

Some rice fields 

outside of the 

above provinces 

provide families 

with 62 kg/ha. 

Evidence 

suggests the 

resource in 

Cambodia has 

been 

underestimated. 

An issue for the 

poor is access, 

constrained by 

the sale of fishing 

lots and in some 

cases, the 

exclusion of local 

fishers and 

reduced quantity 

and size of fish 

migrating. 

bodies contribute 

66 kg/hh/y to 

production in 

Savannakhet. 

Average 

household 

catches in parts 

of Lao PDR can 

range from 40- 

108 kg (US$80- 

215). The 

average value of 

a rainfed rice 

crop is US$100. 

Some Laotian 

riverine fisheries, 

as reported in 

1984, had 

declined by 20%, 

and a 1994 report 

states that 

production in 

lakes and 

reservoirs has 

declined by 60% 

in the past 15 

years. 

Technologies and processes that enhance poor peoples’ 

management of aquatic resources 

kg/per/y. In An 

Giang Province, 

average wet rice 

fish catch is 835 

kg/hh/y and 

consumption is 78 

kg/capita/y; 50 

kg fresh fish and 

28 kg fisheries 

products. 

There are 

indications that 

the catches from 

the Red River 

Delta and the 

Mekong River 

System have 

declined 

considerably over 

the last 10-15 

years. 

Uncertainty in relation to the outcomes of technology use by poor aquatic resource 

users has been highlighted. Reference is made to the desirability of support systems 

that can integrate “local knowledge” and “scientific knowledge”. Participatory 

approaches also have an important role to play. Local knowledge commonly 

includes: 

● time and place knowledge of resource systems; 

● people who use them; 

● local needs; 

● desires; and 

● patterns of behavior.

Processes that enhance poor peoples’ 

management of their aquatic resources 

Incremental 

Participatory 

Adaptive 

Flexible 

Building basic husbandry and 

basic management skills 

Limited financial capital 

Building institutional capacity and 

incentive structures 

Supporting operational budget at 

local institutional level 

Promoting networking among 

sectors of small-scale producers 

From fisheries, the management of ubiquitous small-scale water bodies is of 

particular interest. The water bodies play an important role in subsistence needs and 

income generation. Fisheries technologies exist to increase the standing stock and 

returns to fishing effort. However, initiatives to 

enhance the management of such systems, 

which catalyze changes in use patterns and 

access, raise important issues about 

managing the process, and whether 

benefits accrue to the poor. 

Community-based co-management of fish 

resources can be useful in initiating more 

participatory approaches to the 

management of “nature conservation” 

through protected areas. In central southern 

Laos and Northern Cambodia, fish is the 

most important source of animal protein for 

villagers living in and around protected 

areas. Fisheries can be a good entry point 

for conducting community-based 

collaborative management of natural 

resources. 

Learning and communication 

processes that enhance the 

capability of poor people to 

manage their resources

In the context of learning and 

communication, we are reminded of the plurality of knowledge that encompasses 

our “images of reality” and our “vision for the future”. A proper understanding of the 

differences in stakeholders’ knowledge is important for all those who play a role in 

communication and learning processes. 

The traditional means of communication through 

extension services has tended to focus on information 

transfer from researchers to farmers. Perhaps one 

reason why aquatic resources management systems 

have been ignored and aquaculture systems have 

often favored wealthier farmers is a lack of investment 

in communication processes. Improving dialogue 

might help identify issues relevant to poorer resource-users. Organizations 

involved in traditional aquaculture extensions include NGOs, which work in 

relatively restricted areas, as well as government departments, which have 

a wider geographic coverage. 

Developing the capacity to share information is particular needed. It is also strongly 

advocated to involve support staff and aquatic resource users in developing 

recommendations, though top-down processes are reported to be still common 

place. Improving mechanisms for communication across sectors and between 

countries, provinces, districts and communities is important in creating awareness of 

good and bad management practices at various levels. A better sharing of what 

knowledge exists is needed, especially approaches and processes and the contexts 

in which they have been successful. 

The weak institutional capacity 

of some government (and 

other) providers of services at 

local levels can limit their 

capacity to participate fully in 

learning and communication. 

Learning and communication 

processes should build on 

traditional systems of 

information storage and 

management already 

operating at local levels. Local 

support agencies should be 

assisted to be better able to 

record and manage the 

information they are expected 

to retain and process. 

Institutions, organizations, polices and legislation that shape

aquatic resources management for poor people 

People who are poor find it difficult to draw down services that could support their 

aquatic resources management (and more broadly their livelihood options). 

Promoting pro-poor approaches within policies and institutions is a particularly 

valuable development objective. Understanding the livelihoods of the poor is 

essential to the proper formulation of policies that support their objectives. Once 

again, participatory processes have an important role to play in uniting the poor 

with policy formulation processes. 

From a broad range of contributions one can characterize the following key 

requirements. 

● Expanding the structure of existing support 

agencies (especially local government), 

allowing representation of the poor and 

facilitating a better understanding of poor 

peoples’ livelihoods and their participation in 

policy development processes. 

● Assistance (catalytic) from support agencies for 

local organizations and networking. 

● The knowledge and skills required to administer 

and monitor even simple technologies can 

become limiting factors at provincial and district 

levels. Seeking opportunities to build upon 

existing capacity, at a rate consistent with the stage of institutional 

development, can be valuable. Where institutional capacity and operational 

budgets are limited, the process is likely to be slow and long. 

● The development of a long-term vision and the coordination of donor support 

can often be complex for local institutions to manage. Regional development 

structures may have a role to play in administration. 

In Southeast Asia, international collaboration within and between riparian 

countries will probably be a major determinant of aquatic resource 

sustainability with important implications for poor people’s livelihoods. Stocks 

are shared among different parts of the region sometimes hundreds of 

kilometers apart because of migratory habits of most Mekong fish species. 

Processes leading to the formulation of policies and laws relating to the 

construction of hydro dams, irrigation structures and habitat conversion 

could benefit from information about the dynamics and value of aquatic 

resources.

From the DFID-SEA Aquatic Resources Management Programme. 2000. Draft Final Report: 

Proceedings of the E-Mail Conference on Aquatic Resources Management for Sustainable 

Livelihoods of Poor People in the SE Asia, June 2000, Bangkok, Thailand, 131 pp. (Available 

upon request from stream@eNACA.org.) Originally edited by Graham Haylor and repackaged 

by Matthias Halwart for this publication.

Social and Cultural Considerations in Small-Scale 

Aquaculture 

Aquaculture is a mode of production, which is part of a larger 

agriculture/fisheries/food production system. This larger system is both socioeconomic 

and biophysical in nature. These two features are interdependent, 

interactive and mutually deterministic. Together, they can influence people’s 

decisions and their success in new technology applications and development. 

The production system also involves the local community. One cannot consider 

development as only individual. The household context has immediate impacts on 

women and men as well as on the old and young. The community, political and 

other factors may involve different social classes, castes, or ethnic groups. 

The physical connections of aquaculture through the use of water form a close link 

to wider ecosystems. These wider ecosystems are used and influenced not only by a 

range of biological and physical factors but also by people. 

Aquaculture and its development should be...

People centered. Support 

should be provided only for 

what matters to people. The 

support must be sensitive to 

differences among groups of 

people and should fit their 

current livelihood strategies, 

social environment and ability 

to adapt. 

Responsive and participatory. 

Poor people should be key 

actors in identifying and 

addressing priorities. Outsiders 

will have to listen to and 

respond to the poor. 

Small-scale aquaculture 

Conducted in partnership. 

Partnership is needed in the 

private and the public sectors 

for the development of the 

production system, marketing, 

finance, regulations, technical 

support, training, etc. 

Dynamic. External support for 

aquaculture development 

must recognize the dynamic 

nature of people's current 

livelihood strategies and be 

flexible to changes. 

Multi-level. Concerns at the 

micro-level, the locus of the 

production, must inform the 

development of policy (local 

government and other levels) 

for an effective and supportive 

enabling environment. 

Sustainable. In addition to 

environmental sustainability, 

aquaculture must pass the test 

of social, economic and 

institutional sustainability. 

Aquaculture development intended as “small-scale” must be a poverty-focused 

development activity. As such, it should comply with the principles as adopted by 

DFID as core principles of sustainable livelihoods framework. 

A useful framework to remember consists of the assets that people can draw upon 

for aquaculture development. These are: 

● natural capital, e.g., water, soil, fish stocks;

● human capital, e.g., trained labor, leadership skills, artistic talents; 

● produced capital, e.g., houses, roads, machines, money and financial 

resources; 

● social capital, and e.g., relationships and trust, networks, organizations; and 

● cultural capital. e.g., beliefs, shared world views, folklore. 

People can use these assets to invest in aquaculture development. These are also 

the reserves that can be used as foundations for successful aquaculture. In other 

words, the benefits of aquaculture can create assets other than those reflected in 

the financial benefits. 

Complementation of new technology 

Aquaculture development must be considered within the 

context of sustainable livelihoods and household economy. 

Hence, it is essential to consider family goals and aspirations. 

Complementarity of new technology is essential in aquaculture development. 

Aspects to be considered include the following: 

Technical complementation 

New technology added to a household must complement the technologies 

currently being used. Conflicts will lead to rejection of new technology. 

Social complementation 

Social reciprocities exist and must be considered in introducing new technology. 

Labor exchange is integrated with seasonality and social obligations. Access to 

resources may be determined by previous social conventions or arrangements. 

Economic complementation 

Small-scale producers are by definition resource-poor. Financial capital will be 

limited and new ventures may depend on availability of limited technical and 

human resources. Amount and timing of economic resources are important. 

Political complementation 

Access to common property or other resources may be constrained by existing 

political structures in a community. It is important to know who holds and uses power 

in the community and how their power is linked to power structures outside the 

community. How can the disadvantaged in the community be empowered?

Participation 

Participatory methods can be used to assist communities in 

identifying needs and setting priorities. Simple PRA methods 

such as focused group discussion or problem tree analysis 

are examples. See guidebooks, such as, the Participatory 

Methods for Community-based Coastal Resources 

Management (IIRR, 1998). 

People need to be involved in choices of aquaculture technology and the details of 

the technology. Participation in problem identification and solution will make the 

technology more suitable and acceptable. 

People need to assess what resources are available for aquaculture development 

and how these might be used. They must be central in planning for collective action. 

Availability of human resources 

We cannot assume that there will be enough labor, time and skills available. In poor 

villages the more entrepreneurial people (more qualified and better motivated) 

tend to leave. Fishing and farming are often low-status occupations. 

Availability of time 

Current fishers/farmers will be very busy. Both women and men are occupied most 

hours of the day with current activities to maintain household welfare. 

In aquaculture the benefits from investment will only be obtained much later. 

Investments of time and money will not return benefits of food and income until 

harvest. Fishers are accustomed to receiving the benefits of a day's work on the 

same day. Aquaculture requires a different attitude and planning for such fishers. 

Farmers may be more attuned to this condition. 

Risk tolerance 

The risk factors to be considered are: 

● Current lack of access to resources can make people averse to risk and less 

likely to take up new options. 

● Options and decisions are usually based on experience. What is most 

meaningful is what “worked” in the past.

● Familiarity supports acceptance of risk. The lack of visibility of some 

aquaculture stock may decrease comfort. 

Guide questions for appropriate technology 

A technology, to be adopted/adapted by the target beneficiaries, must be 

appropriate to existing conditions. 

● Is it responsive to needs? 

● Is it affordable? 

● Is it ecologically sound? 

● Is it socially acceptable? 

● Are credit, training, and other support available? 

● Would it require policy advocacy? 

● Is it sustainable? 

Ownership and management 

● Community ownership or individual ownership: Will the development result in 

units of production being owned and operated by individuals or households? 

Or will it result in some form of communal enterprise? In some cultures, 

individual or family ownership is more successful than communal efforts. One 

must ensure that the development is designed to fit the potential social 

organization of the community. 

● Access to the resources: Who controls, owns and/or manages the resources 

necessary for production? 

● Training, credit and other support services should get to the right people. These 

people must first be identified. Are women involved? Are there others not 

visible who play an important role in the production? 

Social and cultural considerations in species selection 

The type of species to be used in aquaculture is critical in the investment process. 

● Demand driven selection of species in aquaculture. What species are 

important to the potential users of aquaculture technology? Is there a market 

or household demand? 

● Harvesting period: consider the timing with respect to religious or other festivals 

and holidays. Prices and availability of excess labor might be affected by

timing. 

● Peak seasons of labor demand for other means of livelihood might be in 

conflict with the seasonality of introduced species. 

Social and cultural consideration in technology choice 

● Availability of easily adaptable technology 

● Cultural and religious acceptance of the technology 

● Appropriate educational levels of users 

● Technology may impact women and men differently. Consider who will be the 

most appropriate user of the technology. 

● Consider special needs depending on the age of the expected participants. 

● Children should not be involved in labor at the expense of their education. 

Social considerations regarding required resources 

● Look closely into why the resources are being used for production. Are the 

resources (e.g., ponds) available for use because the owner intends them for 

aquaculture production? 

Institutional support to the farmer 

● Social and cultural obstacles sometimes exist, particularly for government 

infrastructure, due to different classes of people. 

● Appropriate groups should be mobilized where communal action is needed. 

● Look for traditional or community-based institutions to support new 

development. These are likely to be more socially and culturally acceptable. 

But make sure they are not inclined to limit the spread of the benefits. 

Demonstration of successful technology 

● Social recognition of the best farmers creates role models in the community.

● Role models are important and need to be identified so they will have the 

most impact. 

● Be responsive to what people need. 

Prepared by: 

Gary Newkirk

Socio-Economic Impact of Rural Pond Fish 

Culture 

The “natural” development of aquaculture is influenced by such socio-economic 

factors as: 

● the perceived need or desire for aquaculture products; 

● the suitability of available resources for supplying these products and the 

availability of complementary factors of production; and 

● the knowledge of techniques for aquaculture possessed by the society. 

Technology and technology transfer are major issues in developing the 

fisheries sector in Bangladesh. Towards this end, an extension methodology 

called trickle down system (TDS) of aquaculture extension was developed 

and implemented on an experimental basis during the implementation of 

the project "Institutional Strengthening in the Fisheries Sector in Bangladesh". 

The approach was further applied on a pilot-scale with assistance from the 

Technical Cooperation Program of the Food and Agriculture Organization of 

the United Nations (FAO) to strengthen the extension services system in 

Bangladesh. 

Continuous supervisory technological and institutional support 

catalyzed the farmers’ interests in aquaculture. The homestead 

pond aquaculture assists poor families by providing additional 

income as well as nutritional benefits.

However, these factors are not in themselves sufficient to ensure the development of 

aquaculture. A society with assured and suitable sets of property rights also appears 

to be necessary. Peace, law and order and good environment, when combined 

with the above factors, are likely to be conducive to the development of 

aquaculture. 

The following are the possible socio-economic impacts on the household of fish 

farming. 

Occupational 

changes 

Employment 

generation 

Family 

Approach 

Household 

livestock 

Socio-economic factors Possible impacts 

Living standard 

Fund flow for 

fish culture 

Aquaculture generates more income than rice farming 

does. Because of its profitability, rural farmers and underemployed 

often change their profession to aquaculture. 

Improved aquaculture generates full time employment 

for two persons per hectare and has multiple effects on 

allied activities. 

If a family approach is used, ponds are never 

unattended. Women are empowered because of their 

role in decision-making. Children, however, should not 

sacrifice opportunities for attending school. 

Households are encouraged to maintain livestock 

because of their role in fertilizing ponds. 

Additional income from aquaculture often translates into 

improved housing and sanitation. 

Aquaculture improves access to institutional credit and 

increases savings. 

Nutrition Aquaculture increases the level of fish consumption 

thereby improving family nutrition.

Changes if 

farming 

systems 

Aquaculture changes the culture pattern from 

fry/fingerling-rearing to fish culture. 

Self-confidence The adoption of aquaculture technology increases the 

self-confidence of the farmers’ family; they receive 

improved training on management. This also increases 

the capacity and understanding of the value of 

technical inputs. 

Social relationships Aquaculture helps expand the social network of farmers. 

New relationships can emerge, through marriages and 

friendship. Farmers visit fishery officials for technical 

advise and vice-versa. 

Better use of waste Household waste, poultry droppings and compost are 

used as feed and manure. 

Religion Religious factors sometimes affect aquaculture 

negatively. Appropriate training can improve this 

situation. 

Information Information is crucial during fish disease outbreaks, 

scarcity of fry/fingerlings exists, limited marketing, etc. 

Access to resources Access to resources is fundamental to aquaculture. Multiownership 

of ponds and water resources should be 

settled amicably. 

Availability of 

technology 

Easily adaptable, demonstrated and tested 

technologies are precondition to expanding 

aquaculture.

Education Education plays a major role in adopting and practicing 

new technology. For illiterate farmers aquaculture 

technology should be made understandable in easy to 

follow, pictorial guidelines. 

Law and Order Stable law and order is essential: it reduces the 

incidence of poaching, poisoning and disturbances. 

Communication network Good communication network, i.e., roads and 

transportation facilities is also beneficial in promoting 

aquaculture. 

Institutional 

framework 

To expand and sustain aquaculture benefits to the 

society, an institutional framework must be present. 

Health benefits Fish contains high protein and vitamins and less fat and 

reduces cholesterol-related and protein-deficient 

diseases. 

Human capital The dissemination of aquaculture technology enhances 

human capital (i.e., knowledge, technical know-how, 

etc.). 

Use of water 

resources 

Expansion and enhancement of aquaculture brings 

underutilized water-resources into production: ditches, 

depressions, borrow-pits and seasonal waterbodies. 

Demand driven Aquaculture should be demand driven otherwise losses 

are inevitable. 

Interest/willingness Willingness to undertake aquaculture as well as interest 

to adopt new ideas and/or technologies are important.

Involvement of Women in Small-Scale 

Aquaculture 

Aquaculture is the fastest growing food sector in Asia. However, the vital role of 

women in aquaculture growth has not been adequately recognized. Many issues 

remain inadequately addressed. To ensure sustainability, it is necessary to understand 

issues related to both men and women and develop gender-sensitive interventions. 

Women and aquaculture 

An ethnic women’s group organized by 

CARITAS Bangladesh (with 18 members) in 

Pagalpara, Mymensingh district, has been 

practicing aquaculture successfully for the last 

five years. All aquaculture-related activities such 

as the excavation of four ponds, stocking, 

harvesting and marketing are done by the 

women themselves. Hatchery and market 

accessibility contributed to their success. The 

group makes an average profit of 

US$49/member/year in a pond area of 0.34 ha. 

Though there are no strictly assigned genderspecific 

roles in aquaculture, work that involves 

heavy labor such as pond digging and 

harvesting is led by men. Women, on the other hand, lead activities such 

as stocking, feeding, fertilization and routine caring of pond. These roles 

interchange in different cultures and family environments. 

Traditionally, women have been involved in different stages of small-scale 

aquaculture. They are active caretakers of fish in homestead ponds, cages or even 

in rice fields. The role of women has been especially prominent when the systems are 

located close to their homesteads. Restricted mobility, due to religion or security 

concerns, is a reality that must be considered.

Benefits of women’s participation in aquaculture activities 

Increased 

fish availability 

for family 

consumption, 

thus benefitting 

nutrition. 

Improved 

economic 

situation of the 

family resulting 

from increased 

fish production. 

Upliftment of 

social status 

attributed to 

adoption of 

new 

technologies. 

Children’s education sustained because of improved family incomes. 

Enhanced social capital by establishing good relationships within the 

community (e.g., providing information to other women). 

Productive use of time without adding much to the existing workload. 

Increased status and participation in various decision-making process 

within the family. 

Gender issues that hinder women’s participation in aquaculture activities 

Societal and cultural issues can affect the participation of women in aquaculture. 

These issues need to be addressed through the formulation of plans suitable for 

various social and cultural environments. 

● Restricted mobility limits the productive contribution of women. Mobility varies 

with different cultures, religion and societies. 

● Apart from restricted mobility, norms in some societies limit women’s 

contribution in economic activities. 

● Men generally participate (and dominate) in trainings and cross-visits, 

excluding women from access to information and from the decision-making 

process. 

● In many places women have very limited or no land ownership, limiting both 

access and control over the resources. 

● Many agencies aim to improve women’s status by increasing their access to 

credit. However, credit is not always accompanied by provision of skills. Hence,

women serve only as a conduit for men to procure loans. 

● Low literacy rates among women in many countries hamper information 

acquisition. 

● Very few organized women groups exist to articulate the needs of rural women 

involved in aquaculture. 

● Lack of sensitivity to and respect for gender roles and responsibilities is a 

common problem. 

● Data on women involvement in aquaculture is not available, and policies and 

programs often are not gender sensitive. 

Implemented strategies to address gender issues 

Family approach 

The family approach was found to be successful because it answers the problem of 

not having adequate female participation. Both husband and wife take part in 

training. In conservative communities, early meetings with the family guardians 

proved effective in ensuring participation of female family members in training 

sessions. Establishing trust between the extension staff and villagers is also important. 

Gender day 

"Farmer field school" with family approach 

In the "farmer field school" approach adopted in 

some of the CARE Bangladesh Agriculture and 

Natural Resource (ANR) projects, both male and 

female groups meet separately (due to cultural 

restrictions) for sessions held every two weeks. 

Results indicate that this approach helps women 

acquire knowledge that enables them to take 

active part in decision-making. 

After the first few sessions (conducted separately with male and female groups), 

both groups are brought together on a day designated as their “Gender Day”. On 

that occasion, discussions of gender issues and local problems take place, and

action plans are developed. Later, a midterm review is conducted and necessary 

adjustments are made. At the end of the season, the groups meet to examine the 

progress and set new goals. 

After the learning sessions (held once or twice a month), focus on gender issues is 

ensured. Information materials are used to create awareness and effect changes in 

perceptions and attitudes of both men and women. 

Change in decision-making pattern in family 

A study conducted in the New Options for Pest Management (NOPEST) 

project of CARE Bangladesh indicated that gender awareness programs 

significantly influenced the decision-making process in the family. In the first 

season, a survey indicated that only about 44% of the men consulted their 

wives in making different decisions. However, at the end of the third season, 

more than 92% of the men reported that they consulted their wives in 

decision-making. 

Access to information 

All women may not be able to attend training. For those women who fail to attend 

training sessions, individual attention and support have been found to be useful. 

During the sessions, interaction among women participants is encouraged. Fixing 

targets for each woman to train other women in the community on the techniques

and social issues discussed have shown good results. 

Sample issues discussed after the learning sessions 

People's reaction to the birth of a baby girl 

Attitudes towards boy and girl 

Recreation time for male and female members 

Decision-making process in the family 

Barriers to women development in families 

Gender-based labor division 

Health of women 

Family conflict 

Savings utilization 

Recognition of women's work 

Decline in social values 

Gender sensitive technology development 

In developing technologies, women’s needs should be considered. Technologies 

should not add risk to the end-user and should be women-friendly. 

Input supply 

Gender sensitive technologies 

In Cambodia, termites and other available feed resources are used as fish 

feed. However, Cambodian women treat the task of termite collection as an 

additional work load. Moreover, because of security concerns, they are 

unable to move freely to collect termites. Instead, the green water 

technology, which is effective in promoting the growth of plankton feeding 

fishes, was preferred by women. They understood the benefits of this 

technology in influencing fish growth and began to advocate plankton as 

fish food comparing its effect to that of "mother’s milk to baby". 

In Bangladesh, several women are involved in making prawn/fish feed at 

home for their own use. It has also become an important income generating 

activity as they can sell feed to other farmers in the area. 

Women are comfortable making feeds as they already know 

how to make rice noodles. In fact, they use the same noodlemaking 

machine to make feeds.

Since mobility of women is sometimes restricted, the development of technologies 

emphasizing the use of available resources in the farm is especially suitable for 

women. When external inputs are necessary, they should be available in accessible 

places. 

Division of labor 

Care should be taken to avoid giving women additional work. Proper planning by 

family members (in a threat-free environment) of the daily activities and labor 

distribution reduce the burden on women and increase efficiency. 

Gender sensitive extension staff 

In many countries, there are very few female extension staff members. Male 

extension staff generally tends to serve primarily the needs of men. However, the 

provision of gender education to staff has been found to be useful in changing that 

attitude. 

Studies conducted in different countries indicate that women work longer 

hours than men. Gender sensitization activities should enhance awareness of 

this issue in order to bring changes in work distribution.

Credit systems 

Staff composition 

Depending on the local situation, having male and female 

extension officers might be a useful way to adequately reach 

women. A gender balance in extension staff recruitment is one 

of the strategies that have been tried successfully in many 

projects of CARE and CARITAS Bangladesh. To attract women, 

reserve positions for them. Development of gender sensitive 

policies and enforcing them with the active participation of staff 

have helped ensure gender sensitive outcomes. 

Credit, coupled with appropriate training, is usually helpful to farmers. In some 

countries, like Bangladesh, existing micro-credit systems have inappropriate 

repayment schedules. Most aquaculture species require a three to four months growout 

period. But the existing credit system requires commencement of repayment 

within a week after the loan is obtained. Changing the repayment schedules has 

been found to benefit women involved in aquaculture activities. 

Credit systems need not depend only on available credit facilities. Established 

women’s groups should initiate the formation of a self-help credit system for 

themselves. Each woman member can contribute an equal amount of seed money 

which they can avail of alternately. That way, money procurement is facilitated and 

interest is avoided. 

Small aquaculture systems help improve the livelihoods of people. The provision of 

knowledge to fish farmers, particularly to women, contributes to women 

empowerment and an increase in family income.

Prepared by: 

Anwara Begum Shelly, 

M. C. Nandeesh and A.K.M. Reshad Alam

Impact of Aquaculture on the Environment 

Most of Asia’s aquaculture development took place over the last few decades. This 

is evident by the 244 percent increase in aquaculture production in Asia from 1986 

to 1994. Aquaculture has many positive impacts on the environment. But it also has 

negative impacts, which often occur when there is overexploitation of 

environmental goods and services. The more intensive the operation, the greater the 

demands on the environment. This article discusses in depth some of the negative 

consequences. 

Positive impacts on the environment 

Although aquaculture contributes a lot to improving the environment, the positive 

impact on the environment is not often realized (and documented). Some of these 

are represented below.

Negative impacts on the environment 

1. Loss of ecologically sensitive habitats 

Coastal pond 

aquaculture, whether 

used for extensive 

shrimp culture, semiintensive 

or intensive 

aquaculture, has been 

blamed for large-scale 

losses of mangroves and 

mud flats in several 

countries (e.g., Thailand, 

Indonesia, Philippines, 

Vietnam, etc.). 

Though shrimp 

aquaculture is blamed 

for the destruction of 

mangroves, huge areas 

of mangrove 

vegetation in Asia were 

also lost due to 

community 

development, agriculture, road and ports development, salt producing farms, 

mining, charcoal, fuel, wood extraction, etc. On the other hand, important 

wetlands, including keystone habitats, have been altered for aquaculture purposes. 

The alteration of coastal and inland habitats has negative impacts on fish and other 

aquatic organisms. 

Keystone habitats are 

relatively rare but are 

ecologically 

significant. 

Silvofisheries is an 

integrated mangrove 

tree cultivation with 

brackish water pond 

aquaculture. 

Areas of shrimp culture in former mangrove areas in Asia 

Type of Farm 

Extensive 

Semi-extensive 

Intensive 

Total area 

Total area in region 

(mangrove and non- 

mangrove in has.) 

691,303 

132,935 

85,768 

910,006 

Percentage of area 

which were formerly 

mangrove 

43% 

45% 

31% 

100%

General practices in protecting sensitive wetland habitats, as practiced in coastal pond 

aquaculture 

DOs DON’Ts 

Retain mangrove patches between ponds 

and inlet water sources. 

For extensive practice, use relatively small 

pond areas. 

To compensate for the reduction in pond 

area, utilize improved management 

interventions to increase productivity. 

Encourage silvofisheries model of alternating 

pond with mangroves. 

Practice pond aquaculture in former 

mangrove areas. 

Recognize mud flats 

as important feeding 

habitat for migratory 

birds and various 

aquatic organisms and 

other wildlife. 

Do not use mangrove vegetated soil. It is not 

suitable for pond aquaculture due to its acidic 

nature and the extensive root system of the 

mangroves. 

Do not use large areas for extensive shrimp 

culture. 

Do not encourage coastal aquaculture 

systems with low productivity in large areas. 

Do not open new areas of mangroves for 

conducting pond aquaculture, except under 

exceptional circumstances. 

Do not encourage coastal aquaculture in 

mangrove areas without alternating with 

mangroves. 

Do not convert mud 

flats into aquaculture 

ponds. 

2. Deterioration of water quality and the reduction in carrying capacity of the 

aquatic environment 

As aquaculture becomes more intensive, the amount of wastes released into the 

environment, especially in surrounding waterways, increases. Wastes enter the 

environment in the following ways:

● Direct effluent 

loading due to 

water exchange. 

● Pond bottom 

sludge removal. 

● Effluent water 

discharged into 

the source of 

water intake. 

● Waste production 

from cages in 

lakes, reservoirs 

and marine 

environments 

● Excess feeding, 

animal feces and 

uneaten food, 

which settled at 

the bottom of the 

cage and pen. 

● Use of fresh fish 

rather than 

pelleted feeds as food

The higher the intensity of aquaculture, the more waste is accumulated. In the case 

of shrimp farm effluent, pollution loading is considerably less than from domestic or 

industrial waste. Although chemicals released into water ways can and do have an 

impact on water quality, the use and release of chemicals in aquaculture are less 

than in agriculture and most, but not all, are only marginally harmful to the 

environment. 

Impact of waste and nutrient loading on the environment 

● Can cause eutrophication of water ways leading to plankton crashes and 

depletion of oxygen 

● Self pollution of aquaculture systems 

● Increase in the concentration of ammonia and a reduction of oxygen in the 

water ways reducing the carrying capacity of aquatic environments 

● Excessive development of inland cage culture causes more significant 

reduction in the carrying capacity of the aquatic environment than pond 

aquaculture 

General practices in discharging effluent and maintaining water quality, as practiced in 

aquaculture 

DOs DON’Ts

If effluent is not very abundant, discharge 

effluent water through a wetland area. 

Wetlands efficiently absorb and retain nutrients 

and organic matter from overlying waters. 

If wetlands are not available, discharge 

effluents into a pit or depressed area or into a 

settling pond to store it for a period of time 

before releasing it. If in coastal areas, release 

after storing with rain water, to reduce the salt 

content. 

In coastal areas, the disposal of effluents 

into mangroves located away from open 

waterways can be undertaken in order to 

exploit the capacity of mangrove soils to serve 

as "sinks". 

Dry the pond bottom between two culture 

cycles to increase the microbial degradation 

of accumulated organic matter and to oxidize 

substances in reduced states. 

In coastal areas, use the shrimp pond waste 

sludge in the inter-tidal zone to fertilize 

mangroves. 

Explore possibilities for using pond waste 

sludge to produce fertilizers for vegetable 

cultivation. 

For cage culture, allow a 2 m distance 

between the bottom of the net cage and the 

bottom of the water body to minimize pollution 

and to allow nutrient recycling. 

Determine the 

carrying capacity of 

the aquatic 

environment before 

expanding 

aquaculture activities. 

3. Loss of agricultural land and salinization 

Do not discharge effluent water directly into 

the waterways. 

Do not discharge effluent water without 

allowing the suspended matter to settle. 

In coastal areas, do not dispose of effluents 

into mangrove areas that are very close to 

open water ways and may transport nutrient 

load directly to the open sea. This might cause 

eutrophication. 

Do not start the next culture cycle without 

observing a fallow period, which depends on 

how long it gets the pond to dry. 

Do not dump waste into non-salt tolerant 

agricultural lands, as it will contaminate the soil 

and kill plants. 

N/A 

Avoid using fixed submerged cages, if it is 

not possible to retain a 2 m distance between 

the bottom of the net and the bottom of the 

water way. 

Do not allow 

uncontrolled expansion 

of aquaculture 

activities.

● The lucrative nature of shrimp aquaculture has led to the conversion of many 

paddy fields and coconut-cultivated land into ponds. 

● The innovation of inland culture of marine/brackish water shrimps has led to 

the conversion of rice paddy lands into ponds. 

● The main environmental issues are the potential salinization of soil and fresh 

water wells as salt intrudes into ground water in coastal and inland areas after 

it is transported and added into the ponds. 

● While economic returns are higher in shrimp aquaculture, the value of lost rice 

crops or coconut cultivation could become very high as they become scarce. 

General practices in protecting agricultural areas and preventing saltwater intrusion, as 

practiced in pond aquaculture 

DOs DON’Ts 

Use suitable sites for aquaculture according 

to the accepted site selection procedure. 

Utilize marginal and unproductive lands for 

aquaculture. 

4. Loss of ground water 

Avoid inland areas 

for salt-water 

aquaculture. 

Do not use fertile agricultural lands for saltbased 

aquaculture that has the potential to 

impact the neighboring farms or the 

environment. 

Do not transport salt 

into inland areas in 

order to practice salt 

water aquaculture. 

● Ground water extraction is being done to dilute saline water in ponds where 

aquaculture is undertaken for low salinity tolerant species. 

● Ground freshwater extraction in large quantities may lead to land subsidence. 

● Ground freshwater extraction can lead to conflicts between users, for example 

agriculture and domestic ground water consumers. 

General practices in protecting ground water resources, as practiced in pond aquaculture in 

saline areas 

DOs DON’Ts 

Adopt a switch over strategy to culture high 

saline tolerant species in high saline areas. 

Do not use low saline tolerant species in 

areas where high salinity prevails.

5. Spread of diseases 

Assess the ground 

water availability 

before extracting it for 

aquaculture. 

Do not use ground 

water in large 

quantities to dilute 

saline water without 

assessing the 

availability of the 

resource, and the 

impacts it may cause. 

Diseases could be spread from one aquaculture system to another and to the wild. 

Disease is a very serious concern both for aquaculture and wild aquatic organisms. 

The use and sometimes abuse of antibiotics in more intensive farming has led to 

multiple drug resistance among pathogens, facilitating the spread of diseases. Every 

effort should be observed to control and prevent transmission of diseases. 

6. Introduction of exotic species 

The introduction of non-native fish species into the wild through aquaculture may 

lead to a serious problem in the long run. 

● The golden apple snail, introduced for aquaculture, 

has become one of Asia’s most serious rice pests. 

● Captive aquatic animals inevitably escape and can 

colonize natural waters: an estimated two-thirds of 

species introduced into tropical inland waters have 

become established, although many had positive 

economic benefits. 

● Exotic species (African catfish, 

tilapia and silver carp) in 

inland water could pose such 

risks as habitat destruction, elimination of local 

species by competition or predation, and genetic 

degradation of local stocks. All this results in a loss of 

biodiversity. 

● The introduction of genetically modified organisms 

(GMOs) can cause ecological damage and 

imbalances. 

● Introduced strains can alter the gene pool of 

indigenous species, leading to genetic pollution and 

the loss of indigenous organisms and biodiversity. 

● The accidental release of piranhas in Sri Lanka and

Vietnam and knife fish in Sri Lanka into natural water ways is now a serious 

environmental concern. The fish were obtained for ornamental fish breeding 

and culture farms. 

DOs DON’Ts 

Identify and promote native fish species for 

aquaculture. 

Review strategies associated with the use of 

exotics and GMOs for aquaculture and further 

develop practical codes for risk assessment 

and management, as emphasized in the FAO 

Code of Conduct for Responsible Fisheries. 

them for culture. 

Focus attention on 

implementation of 

strategies/actions by 

signatories to the 

Convention on 

Biological Diversity. 

Check the prohibited 

or restricted list of 

species before using 

Do not introduce exotic species, which have 

the potential to cause a negative impact on 

the environment. 

Do not culture or 

introduce prohibited or 

restricted species.

Prepared by: 

P.P.G.S.N. Siriwardena, 

Michael J. Phillips and Ian G. Baird

Conservation of Aquatic Genetic Diversity 

Genetic variation within a population allows the species to adapt to environmental 

change or stress. It is important for the populations to be able to reproduce, survive, 

and successfully evolve in a changing environment. Populations with higher genetic 

diversity are more likely to have at least some individuals that can withstand 

uncertain changes of the environment. They can pass these genes to future 

generations. Genetic diversity has been shown to have a positive relationship with 

measures of fitness such as growth, fecundity and survival. It should be conserved 

because it is a fundamental component of adaptation and evolutionary success. 

Foods 

In the fields of fisheries and 

aquaculture, conservation and 

utilization of genetic diversity are 

important as aquatic animals, including 

fish, are major food sources harvested 

from natural populations. Genetic 

diversity is very important in a species 

being bred for desirable traits. Likewise, 

it provides the foundation for the 

rapidly growing biotechnology industry. 

Medicines and tools for biomedical research

Genetic diversity and stock enhancement 

Long before the birth of modern medicine, 

shamans and herbalists have used aquatic 

organisms as medicines. The aquatic 

environment is home to many animal phyla 

that are not found on land, so its biochemical 

diversity is great. The pharmaceutical potential 

of aquatic organisms is very high especially in 

the tropics. Kelp is a very good source of 

iodine. Cod and shark liver oils were used as 

sources of vitamins A and D before other 

sources were developed. 

Dwindling aquatic resources led to the development of hatcheries for rearing and 

releasing juvenile fish. Some populations of Pacific salmon are dependent upon 

hatchery seed. Stock enhancement is also being considered to rebuild the depleted 

stocks of the abalone and tuna. The following are some approaches that can 

minimize the loss of aquatic genetic diversity: 

● The genetic structure of the hatchery stock should be as close as possible to 

the genetic structure of the wild population. Negative genetic impact is likely 

to occur when there are big genetic differences between the hatchery stock 

and the wild population. 

● Use a large number of parents. The use of very few parents in the hatchery to 

produce numerous seeds for release into the wild also increases the risk of loss 

of genetic diversity. 

● Avoid introduction of alien fish into the wild. Local varieties can be genetically 

contaminated if different varieties of even the same species are introduced 

into the wild to enhance natural stocks. Import of exotic breeds is one of the 

reasons for the disappearance of local breeds. 

● Do not release seeds from stocks that have been made to adapt to hatchery 

conditions. The genetic changes, which occur in cultured fish, are expected to 

lower their reproductive success in the wild, as well as their offspring. Hatcheryreared 

fish also increase the spread of infectious diseases and parasites to wild 

fish.

The introduced eleotrid Hypseleotris agilis led to the 

local extinction of the endemic cyprinids of Lake 

Lanao, Philippines. 

The introduction of the nile perch Lates niloticus 

dramatically reduced the fish biodiversity of Lake 

Victoria, Africa. 

Genetic strategies for use in aquaculture hatcheries 

The aim of aquaculture hatcheries is to select seeds that have specific production 

traits and should not be used for stock enhancement. 

Some strategies that can be adapted to avoid inbreeding and loss of diversity 

● Use a large number of parents. This becomes a problem in highly fecund 

species such as Indian and Chinese carps, where only a few broodstock can 

easily meet fry production needs. The general recommendation, for short-term 

period, is to use 50 males and 50 females. 

● Keep the sex ratio as narrow as possible. The best effective population size can 

be obtained by a ratio of 1:1. 

● Avoid mating of closely related individuals. 

● Use a rotational mating scheme. This minimizes relatedness of parents. 

● Avoid accidental release of fish from culture facilities. Culture of fish results in 

divergence from the wild type. Genetically altered fish from culture facilities 

represent a threat to the genetic diversity of wild populations. 

● Avoid mixed spawning of different species. 

Threats to aquatic genetic biodiversity 

Biodiversity is being lost from nearly all aquatic ecosystems at an alarming rate due 

mainly to the rising human population and anthropogenic processes associated with 

development. The three major threats to genetic diversity within species include 

extinction, hybridization, and loss of genetic variation within and between 

populations.

Options for the conservation of aquatic genetic diversity 

The conservation of aquatic genetic resources should be addressed in developing 

countries even if the immediate concern is to increase food production. It is feared 

that the genetic diversity of aquaculture species will decline as new improved 

breeds of fish are spread worldwide, replacing locally cultivated landraces and the 

remnants of wild populations. 

Ex situ genetic conservation in gene banks

Ex situ conservation is the maintenance of a genetic 

resource either as frozen sperm, eggs or embryo in 

gene banks or as samples of living breeds in a secure 

environment. A national gene bank for salmon was 

established in Norway for the Norwegian wild Atlantic 

salmon. More recently, gene bank for tilapia has also 

been established in the United Kingdom. Ex situ 

conservation may not be feasible in developing 

countries because of the large amount of genetic 

diversity available and the expensive maintenance of 

collection. 

On-farm genetic conservation 

One conservation option for developing countries is 

on-farm in situ conservation of genetic resources. An 

important feature of sustainable, on-farm genetic 

conservation is that relatively simple genetic 

technologies can be used to develop a variety of 

aquaculture breeds specially adapted to local 

conditions and diverse farming systems. For example, a simple farm-based tilapia 

selection procedure developed by SEAFDEC, Philippines with a tilapia farmer using 

locally available tilapia breeds generated a 6-9% response to selection for increased 

length, after only one generation of selective breeding. 

Use of local breeds adapted to local conditions is a conservation tool that allows the 

maintenance of multiple qualities. Likewise, this will minimize the dependence of 

farmers on a franchise-dealer type of seed distribution. In the desire of developing 

countries to increase fish production, perceived superior breeds of fish are often 

imported. Local and (frequently) better adapted breeds for local conditions are 

displaced.

References 

Basiao, Z.U. and R.W. Doyle. 1999. Test of Size-specific Mass Selection for Nile 

Tilapia, Oreochromis niloticus L., Cage Farming in the Philippines. Aquaculture 

Research 30 (5): 373-378. 

Doyle, R.W., N.L. Shackell, Z. Basiao, S. Uraiwan, T. Matricia, and A.J. Talbot. 1991. 

Selective Diversification of Aquaculture Stocks: A Proposal for Economically 

Sustainable Genetic Conservation. Can. J. Fish. Aquat. Sci. 48 (Suppl. 1): 148-154. 

FAO. 1993. Report of the Expert Consultation on Utilization and Conservation of 

Aquatic Genetic Resources. FAO. Fish. Rep. 491. FAO, Rome. 

Philipp, D.P., J.M. Epifanio, J.E. Marsden and J.E. Claussen (editors). 1995. 

Protection of Aquatic Biodiversity. Proceedings of the World Fisheries Congress, 

Theme 3. Oxford & IBH. Publishing Co. Pvt. Ltd., New Delhi. 

Pullin, R.S.V. and C.M.V. Casal (editors). 1996. Consultation on Fish Genetic 

Resources. ICLARM Conference Proceedings. 51, 61 p. 

Pullin, R.S.V., D.M. Bartley and J. Kooiman (editors). 1999. Towards Policies for 

Conservation and Sustainable Use of Aquatic Genetic Resources. ICLARM 

Conference Proceedings. 59, 277 p. 

Prepared by: 

Zubaida Basiao

Development Assistance for Small-Scale 

Aquaculture 

People who want to start or improve small-scale aquaculture activities often look for 

help in the form of better information or financial assistance. An extension agent, 

even a generalist, should be alert to opportunities to steer these people towards 

good information based on their knowledge of possibilities and resources available. 

Means to develop assistance for small-scale aquaculture

● Appropriate extension literature 

should be available. This could 

include “how to” information, lists 

of sources of seed stock or 

production inputs, etc. The 

literature has to be simple and 

well illustrated for easy 

understanding. Much extension 

literature has already been 

developed and could be 

adapted to local conditions, 

including translation into the local 

language. Likewise, centrally 

located subject matter specialists 

with more specific technical knowledge could produce bulletins, leaflets and 

other teaching aids with the help of media specialists. 

● Rural banks have to prepare for loan applications for small-scale operations. 

Many poor people cannot borrow for lack of collateral to back up their loan 

requests. Sometimes, seed sellers or other suppliers can also serve as sources of 

informal credit and production information, especially when they want 

borrowers to succeed and be able to repay their loans. In some settings, 

groups have been formed with savings plans or credit guarantee capacity that 

have helped people enter into small-scale aquaculture enterprises. Caution is 

needed because some lenders may impose unreasonable conditions on loans 

or charge usurious rates for credit. 

● Extension workers should 

promote proven practices 

adapted to local 

conditions. An important 

extension responsibility is to 

dissuade people from illadvised 

schemes not 

founded on valid 

principles. 

● People need to know 

where and how to access 

available technical 

support. Aside from 

government programs, 

literature or advice on 

how to use products or 

services may be provided 

by feed retailers or other 

related businesses. 

● Where aquacultural development has been targeted, specific projects are in 

place to provide assistance, often with support from international donor

organizations. The nature of such projects varies and care is needed to ensure 

that support systems provide assistance on a long-term basis and not merely for 

the duration of the project. 

● Group teaching, learning and participatory opportunities should be explored. 

Producer organizations are often helpful and special programs involving 

women need adequate consideration. Some of the most successful 

technology transfers have occurred when extension workers facilitated the 

formation of groups where producers can share information and seek 

collective representation in addressing their needs. 

● Media campaigns through 

radio, television and 

newspapers often 

generate interest if 

accompanied by 

information about where 

and how a person can get 

further assistance. Posters, 

large signs or small signs on 

demonstration ponds can 

get attention. Traveling 

folk theater presentations 

have been used in some 

cultures. Even portable 

loudspeaker systems 

passing through communities, a process called “miking”, has potential for 

communicating in rural areas. 

● School curriculum models can create public awareness. Children often bring 

information to their families. They represent the generation of future 

aquaculture adopters. Children may also have the reading and computational 

skills lacking in older generations. They can apply these skills to family fish 

farming operations. 

Caritas-Bangladesh organized 17 landless farmers in Rajshahi 

District who were interested in starting an aquaculture 

enterprise. The group met fortnightly and contributed a small 

fee at each meeting for the training received from Caritas. 

After a few months, the group had built up enough funds to 

lease a 4,000 sq m pond, with Caritas advancing 80% of the 

credit needed. The operation was so successful that the group 

quickly expanded their operation by adding three additional ponds. The 

group was also able to start a small fish hatchery through Caritas’ 

encouragement, training, and credit support. Five years later, the group had 

repaid all its loans. Now, it operates 11 ponds and a commercial fingerling 

nursery system using seed from its hatchery. It employs three full-time laborers 

to assist in maintenance of facilities.

● Research agencies need to participate in outreach programs. Such 

participation helps researchers learn the real problems faced by producers 

and where research efforts need to focus. 

Prepared by: 

John Grover

Introducing Aquaculture into Farming Systems: 

What to Look Out For 

Integrated farming systems have been the subject of extensive research because of 

their socio-economic, institutional and environmental implications. If aquaculture is 

considered as an additional component of a farming system, a re-assessment of the 

system’s conditions is necessary, especially if aquaculture is not a traditional pursuit. 

The guide questions presented in this paper are aimed 

at farming communities. However, they 

can be adapted to other situations like river, estuary, and marine 

communities. 

Unfortunately, there is no quick and easy blueprint on how to successfully integrate 

aquaculture into the diverse range of smallholder farming systems. Social, economic, 

cultural, institutional and environmental factors vary between places and will always 

need careful study and understanding before aquaculture can be introduced into 

existing farming systems. In China, where people have been successfully integrating 

aquaculture with other farming systems, the setup evolved in harmony with specific 

social, economic and cultural conditions. If these specific systems were to be 

transferred to other regions, there is no guarantee that they would succeeed due to 

different resource availability, know-how and traditional farming practices.

Below are some of the important considerations in integrating aquaculture into 

smallholder farming systems: 

Sufficient incentives 

● Are fish part of the diet of farming 

households? Are fish an important food 

item in the community? If so, where do 

the fish come from - capture or culture? 

At what price? Is there a perceived 

need for additional fish? 

● Would aquaculture fit well into the 

existing farming system? Would it make 

use of and complement the existing 

crop and livestock activities? Would the 

aquatic produce improve the nutritional 

status of the farming household? Would 

aquaculture be a new income source in 

addition to existing ones (e.g., poultry, 

ducks, livestock, vegetables and plant 

nursery)? 

● Can the produce be marketed at 

relatively low cost? Can poorer 

consumers afford it? If the product is 

consumed at home, does it substitute for 

a good or item that would otherwise 

have to be purchased by the 

household? 

● Would the additional income derived 

from aquaculture be sufficient incentive 

for the farmer to make the additional 

investments in terms of money, labor and 

time? 

● Do farmers have access to the market? Is it easy to bring produce to the 

market? Do price structures provide for economic feasibility, considering 

instrumental and operational costs? Are there alternative/wider market 

implications? Are there other markets – nationally or internationally – that may 

be tapped? 

Sufficient resources

● Are there sufficient farming systems resources (labor, water, land, initial capital, 

etc.) to support an additional aquaculture component? What are these 

resources? Can aquaculture replace an existing farming system component 

and provide more returns with equal or less opportunity costs? 

● Will the use of natural resources for aquaculture take away resources that are 

important for wild capture fisheries or aquatic biodiversity? 

● Are the natural resources necessary for aquaculture being shared by other 

users? Could this create conflict between users? 

● Is credit needed? Would it be available at interest rates affordable to the 

farmers? 

Sufficient know-how 

● Is there sufficient know-how within the household to successfully manage an 

aquaculture component? Is it available from outside on a sustainable basis or 

can it be brought in from outside? 

● What are the skills/knowledge required? Is the technology robust, simple, easy 

to use and appropriate to farmers’ capacity? Are farmers likely to sustain 

adoption? 

● Will the acquisition of knowledge and skills involve all members of the farming 

household? 

● Do local people/government know about potential impacts of aquaculture 

on other aquatic resources? Can they control the situation to avoid or mitigate 

potential impacts? 

Reliable supply of production inputs 

● Are essential 

inputs, such as fish 

juveniles or 

breeders, feed 

and fertilizer 

locally available? 

Are these inputs 

available at costs 

that will make 

production 

economically 

viable? 

● Are there sufficient surplus agricultural products that may be used in 

aquaculture as inputs? Are they available on-farm? Do they have to be 

purchased? If so, is there an affordable and reliable supply? 

● If juvenile/small fish are being used as feeds, does this practice have 

ecological and/or social implications (e.g., diminishing the natural food for

other native fish species or as food for poor disadvantaged people)? 

Reliable and effective development support 

● Is development support for aquaculture available and accessible to the 

farmer? Is it reliable and efficient? 

● What are the costs involved in receiving this support? Who will pay? Can it be 

delivered on time and is it cost-effective? 

● Is there sufficient government support in terms of extension work and training? 

How could the private sector be involved? Does the farmer have the capacity 

to consider all aspects in a balanced manner pertaining to aquatic resources 

use and management? 

Sufficiently developed and stable market 

● Is there sufficient and stable demand for the produce? Can peak harvests be 

absorbed? 

● Can peak harvests and periods of low supply and related market problems be 

avoided by culturing several species throughout the year? 

● Will the setting up or use of present cooperatives (community based 

operation) facilitate marketing? 

● Does communication support quick marketing? What processing or 

preservation alternatives are there? Are there any value-adding opportunities? 

● Will the increased availability of aquaculture fish result in decreased value of 

natural fish? Will it impact those who harvest wild fish? 

Social and cultural factors 

● Is the inclusion of aquaculture in the targeted farming system socially and 

culturally acceptable? Does aquaculture conflict with given value and 

behaviour patterns (e.g., sense of ownership or negative impacts of livestockfish 

integration) on religious norms (e.g., in Muslim societies)? 

● Can it create new problems regarding the existing resource use system? 

● Does it imply changes in existing production systems, for example from 

individual farming-based systems to collective production? Or can it have 

negative consequences for the existing gender specific division of labor 

system, for example, by putting additional burden on women? Will it 

inadvertently promote the use of cheap child labor? 

● Will an introduced technology change the distribution of control, decision 

making or sharing of benefits within the household (gender and age 

consideration)?

● Is there a potential for social conflict because of the multiple use of resources? 

● Would management practices of neighboring farmers affect introduced 

aquaculture, e.g., through the use of pesticides? 

● Are the beneficiaries convinced and committed to improve their status (health 

and income, empowerment through aquaculture) 

● Is the fish culturally important to the community? 

● If aquaculture is community-based, would it be possible to go for social action 

establishing human right/equity after the project? 

● Do the beneficiaries have other alternatives to allow the fish to grow? 

● If the resources are common property, how can they be accessed for 

aquaculture? Are there opportunities for aquaculture to provide a focus for 

communal efforts (seed supply, training, sharing labor, etc.), which can 

enhance social relationships? Will aquaculture options resolve existing conflicts 

by providing a forum for people to reach consensus on resource allocation or 

use?” 

● Land ownership 

Environmental factors 

● What are the potential environmental impacts (carrying capacity of the local 

resources)? 

Prepared by: 

Matthias Halwart and Julia Lynne Overton with workshop participants

Importance of Fish in Household Nutrition 

Rice often constitutes up to 60% of the daily food intake of most Asians. It is often the 

major source of energy and nutrients in their diet. However, only traces (and 

sometimes none at all) of some essential nutrients like Vitamins A and C, iron, calcium, zinc and iodine 

are found in rice. These nutrients, therefore, must be supplied by other foods. The relationships among 

food, energy and essential nutrients must be seriously considered in order to ensure food and nutrition 

security. 

The "Green Revolution" averted some problems of starvation. But efforts to increase the production of 

staple cereals, and the energy and protein that they provide, failed to address health problems related 

to nutritional deficiency. Advances in agricultural production have, therefore, not been clearly linked to 

human nutrition and health needs. The problems of malnutrition and health, to a great extent, can be 

addressed by improving access to quality and diverse food types. Fish has the potential to ensure a 

quality diet. 

Diet-related health problems in developing world 

Problem Links to health* People affected Impacts 

Insufficient food 

Low birth weight (

many of these and other less widespread problems of malnutrition. 

Source: 

1 Administrative Committee on Coordination-subcommittee on Nutrition. 1992. Second Report on the World Nutrition Situation, Vol. 1: 

Global and Regional Results. Micronutrient Deficiency - The Global Situation. United Nations, New York, p. 80. 

2 United Nations Administrative Committee on Coordination-sub Committee on Nutrition. 1993. Micronutrient Deficiency: The Global 

Situation. SCN News 9: 11-16. 

Fish protein 

● Fish protein is of high quality as it contains all the 

essential amino acids necessary for physical growth 

and maintenance. 

● It is highly digestible (85 - 95% digestibility) and has 

favorable taste. 

In Bangladesh, only 6% of the daily food intake is of animal 

origin, with fish accounting for about 50%. By contrast, rice 

constitutes 60% of the daily food intake and contributes 

78% of the protein in the diet (Ahmad and Hassan, 1983). 

But rice protein is poor in lysine, an essential amino acid. 

Hence, rice protein must be supplemented with lysine from 

fish protein. The combination would provide a high quality 

protein diet. 

Fat soluble vitamins 

Vitamins A and D 

Water soluble vitamins 

Thiamin 

Riboflavin 

Niacin 

Vitamin B12 Fish oil 

● Most fish are relatively low in total fat and relatively high in 

polyunsaturated fatty acids. Polyunsaturated fatty acids, such as 

omega-3 fatty acids in fish oil, have been found to decrease blood 

triglyceride and cholesterol in animals and humans. Thus, 

adequate consumption of fish helps maintain a healthy heart and 

lowers the risk of stroke and heart attack. 

Vitamins and minerals 

● Fish is a fairly good source of fat and water soluble vitamins. 

Vitamin A is present in fish as retinol, which is readily absorbed 

and utilized by humans. In vegetables, Vitamin A comes as Bcarotene, 

which is not as readily absorbed as retinol and, to 

some extent, is lost in cooking. Among the local fish in 

Bangladesh, Mola (Amblypharyngodon mola) and Dhela 

(Rohtee cotio)stand out as rich sources of Vitamin A. 

● Fish contributes enormously to the mineral supply in the diet. 

Minerals such as iron, copper, zinc, magnesium, calcium and 

phosphorus are essential for several vital metabolic functions 

of the body.

– Iron is necessary for hemoglobin 

formation in the blood. Unlike iron in rice 

and other plant sources, fish iron is more 

readily available. Moreover, fish protein 

improves the utilization of rice iron for 

hemoglobin formation. Thus, when taken 

together, fish and rice enhance 

hemoglobin formation in the blood and 

can therefore address the problem of iron 

deficiency or anemia. 

– Calcium and phosphorus are 

essential for bone formation. Small 

fish, that can be consumed with their 

bones and heads, constitute good 

sources of these minerals. In 

Bangladesh, small fish are important 

calcium sources as milk and milk products make up only a small portion of the diet. 

Small indigenous species (SIS) 

– Iodine deficiency is a major problem 

in Bangladesh causing goiter and 

cretinism and retarding growth. About 

70% of the population are deficient in 

iodine, of which 47% have goiter with 9% 

having visible goiter. The goiter rate was 

reported to be higher (51%) in flood 

prone areas. 

Recent studies conducted in both rats 

and humans showed that small fish 

was as good a calcium source as milk. 

Fish and rice constitute the major components of the Bangladeshi diet. But majority of the fish eaten by 

the rural poor are the small indigenous species (SIS) that grow to a maximum length of about 25 cm. 

However, many SIS are less than 10 cm. long (Felts et al, 1996) and are typically eaten whole, with organs 

and bones. Analysis of SIS showed that they contain large amounts of (often limited) micronutrients and 

minerals. 

Vitamin A, Calcium and Iron Content in fish 

Fish species (per 100 g raw, edible parts 

SIS 

Vitamin (ug) Calcium (mg) Iron (mg) 

Mola (Amblypharyngodon mola 1960 1071 7 

Dhela (Rohtee cotio) 937 1260 - 

Darkina (Esomus danricus) 1457 - - 

Chanda (Parambassis spp.) 341 1162 - 

Puti (Puntius spp.) 37 1059 - 

Kaski (Corica soborna) 93 - -

Large fish 

Hilsha (Hilsha ilisha) 69 126 3 

Silver carp adult (Hypophthalmichthys molitrix) 17 268 - 

Rui (Labeo rohita) 27 317 - 

Silver carp juvenile (H. molitrix) 13 - - 

Tilapia (Oreochromis niloticus) 19 - 5 

Source: S.H. Thilsted, N.Roos and N. Hassan. 1997. The Role of Small Indigenous Fish Species in Food and 

Nutrition Security in Bangladesh; ICLARM Quarterly, July - December 1997. 

Unfortunately, over fishing and deterioration of natural habitats, largely due to indiscriminate use of 

pesticides, have resulted in a decline in the number of SIS. The importance of SIS is also often overlooked. 

The species are often called "wild" or "weed" fish and there are no available statistics on them. 

Agricultural systems, including flood plains, fisheries and aquaculture, must protect and promote the 

production of small fish along with carps in order to make them accessible in greater quantities for 

consumption. Nutrition education popularizing the production and consumption of SIS can help 

enormously in improving food and nutrition security. 

References 

Advantages of utilizing SIS 

Unlike large fish, SIS are eaten in small amounts many days per week thereby becoming a 

part of everyday diet. 

With a little oil and vegetables, a variety of dishes can be made. 

Small fish are also more equally distributed among family members. With a big fish, the 

man gets a larger share. 

Future research needs 

1. A feasibility study on the polyculture of carps with small indigenous fish species in 

Bangladesh. 

2. Analysis of the nutrient composition of all commonly consumed fish species in Bangladesh. 

3. A study on the linkages between fish biodiversity and human nutrition. 

Ahmad, K. and N. Hassan. 1983. Nutrition Survey of Rural Bangladesh. Institute of Nutrition and Food 

Science, University of Dhaka. 

Felts, R.A., F. Rajits and M. Akhteruzzaman. 1996. Small Indigenous Fish Species Culture in Bangladesh. 

Technical Brief. Integrated Food-Assisted Development Project, Bangladesh. 

Prepared by: 

Nazmul Hassan

Managing 

the Introduction of Exotic Species 

Globally, introductions of aquatic species have been undertaken on a wide scale. 

The FAO Database on Introductions of Aquatic Species (DIAS, http://www.fao.org/fi/ 

statist/fisoft/dias/index.htm) has 3,150 records on introductions of 654 aquatic 

species from over 140 families. Aquaculture is one of the primary reasons for the 

deliberate introduction of aquatic species. Other reasons include: 

● biological control 

● trade 

● accidental introductions 

● establishment of wild populations 

● sport and recreation 

● research 

● forage and bait 

● commercial fisheries 

● food security 

● unknown reasons 

Examples of introductions 

Introduction of species is defined 

as the human assisted movement 

of an organism to an area outside 

of its present range, so not 

necessarily crossing national 

borders.

Examples of introductions of exotic species are many. Following are a few examples 

of introductions of aquatic species, in particular: 

● The introduction of ice fish (Neosalanx tangkahkeii taihuensis) from Taihu Lake 

to other lakes and reservoirs in China to exploit the underutilized zooplankton 

resources, resulted in the rapid establishment of natural populations of this 

species. For example, the yearly yield in Dianci Lake, where the ice fish was 

introduced in 1979, increased by an average of 1500 tons. 

● The silver carp (Hypophthalmicthys molitrix), introduced in the Gobindsagar 

reservoir in India, improved fisheries production from 160 tons in 1970-71 to 964 

tons in 1992-93 (V.V. Sugunan, 1995). 

● On the other hand, the introduction of the common carp (Cyprinus carpio) 

into the upland lakes of Kumaon Himalayas, the Dal lake in Kashmir, 

Gobindsagar and the reservoirs in the northeast of India. led to the extinction 

of several snow trouts (Schizothoraichtys nigor, S. esocinus and S. curvifrons) 

from these habitats. 

● The introduction of the clupeid fish (Limnothrissa miodon) from Lake 

Tanganyika to Lake Kivu in Africa to exploit underutilized zooplankton 

resources resulted in the formation of a significant artisanal fishery with an 

estimated sustainable yield in excess of 13,500 tons per year, apparently with 

minimal side-effects. Higher benefits have also arisen from the introduction of 

the same fish into Lake Kariba in Zimbabwe. 

● The golden apple snail (Pomacea 

canaliculata), indigenous to tropical 

and temperate South America, was 

imported into Asian countries, 

including Taiwan, the Philippines, 

Vietnam and Thailand, in 1980s 

mainly as food for humans. It soon 

escaped into the wild and attacked 

rice voraciously. Myanmar, 

Bangladesh and India, are currently 

threatened with infestation of this 

snail (Halwart, 1994). 

● The widespread use throughout Asia 

of tilapia (Oreochromis spp.), 

indigenous to Africa, has resulted in significant aquaculture production of lowcost 

protein especially for the rural poor. Similar benefits have arisen from the 

widespread culture of the common carp (Cyprinus carpio). 

● In other areas, these same fishes are considered noxious pests that disrupt both 

natural ecosystems and, in the case of tilapia, the aquaculture sector itself, 

highlighting the complexities of introductions. 

● Introductions have been used successfully to help control nuisance aquatic 

species. For example, grass carp (Ctenopharyngodon idella) is used to control 

submerged weeds in lakes, reservoirs and irrigation canals. The introduction of

snail eating fishes and mosquito fish (Gambusia affinis) assisted in the control of 

vectors of major water-borne diseases, like schistosomiasis and malaria. 

● Results of an introduction are not 

completely predictable nor 

always positive. Introductions are 

now considered among the main 

threats to natural aquatic 

populations. The introduction of 

Nile perch (Lates niloticus) into 

Lake Victoria, Africa, changed 

primarily small-scale artisanal 

fisheries into multi-million dollar 

commercial fisheries that support 

industrial processing and export 

ventures, but threaten to make 

extinct several hundred 

indigenous species of fish. 

Similarly, the accidental 

introduction of Hypseleotris agilis 

in Lake Lanao in the Philippines 

led to the extinction of most 

endemic cyprinids in the lake. 

● Widespread movement of 

cultured tilapia in Africa has 

resulted in so much interbreeding with wild species or strains that natural 

populations are now extremely difficult, sometimes impossible, to locate. 

Caution! 

The effects of introductions can take a long time to 

develop as in the case of the almost 100-year delay 

between the sea-lamprey (Petromyzon marinus) 

gaining access to the North American Great Lakes and 

the subsequent decimation of fish stocks there through 

predation and parasitism. 

Management of introductions 

The adverse impacts of introductions are not limited to conspicuous predatory 

species: examples of non-predatory interactions include the aquatic weeds, 

crayfish, tilapias and carps. 

Reports on the adverse effects of introductions are many. These include devastating 

effects on biodiversity, reductions in production from capture fisheries, aquaculture 

or other sectors, and significant physical disturbances of both natural and man-

made environments, resulting in serious socio-economic hardships and economic 

costs. 

Due to the conflicting outcomes of introductions, codes of practice to assess their 

benefits and risks have been developed and adopted by a number of countries or 

regional bodies. 

While there are considerable benefits from introducing aquatic species (17% of 

world finfish aquaculture production is from introduced species), risks are also 

involved. As such, a set of guidelines on eventual introduction of a species1 is 

proposed here. 

Experience has shown that animals eventually escape the confines of a facility, thus, 

introduction of new species for aquaculture should be considered as a purposeful 

introduction into the wild, even if the quarantine or hatchery facility is a closed 

system. 

Before considering the introduction of a particular species, seriously look for a local 

alternative first. Delay the introduction if a local species shows promise. Study what 

potential use the local species is intended for. This point cannot be stressed enough 

because, often a local species is available but it is not known to fulfill the identified 

purposes. 

When the introduction of a species is considered, someone, an organization, private 

business or government agency, hereafter called the introducing entity, must be 

responsible for the transport of the species. To ensure that introduction of aquatic 

species proceeds responsibly, the following guidelines are proposed, based on the 

ICES/EIFAC codes of practice, which have been adopted in principle by FAO 

regional fishery bodies. 

The introducing entity should develop a proposal, which includes: 

● Planned use of the species, planned benefits and constraints 

● Location of the facility/waterbody where the species are going to be 

introduced and who the stakeholders are in that facility/waterbody (national 

or international) 

● Biological information on the species 

● Geographical location of the species being proposed and information on that 

area 

● A description of similar introductions of the considered species in other areas, if 

available

The review panel should be independent, and not linked to the introducing 

entity. The formation of an external review panel, with the potential 

participation of foreign experts, may be considered. Another option is a 

panel, with the participation of those knowledgeable in local conditions and 

priorities. Of course a combination of the two is another possibility. 

The review panel should be multidisciplinary and should include 

experts in: 

capture fisheries, aquatic ecology, aquaculture, fish health and 

quarantine, human health, socio-economics, conservation, 

genetics, agriculture, private sector development, and rural 

development. 

An independent review should be 

conducted by a panel to evaluate the 

proposal, the impacts and risks/benefits 

of the proposed introduction. The 

panel can look into: 

● Ecological requirements/ 

interactions and genetic 

concerns: 

– the potential range of 

establishment 

– the potential ecological 

consequences 

– the potential genetic 

consequences of the 

introduction 

– desirable genetic bases of 

stocks used, and 

– unintended or undesirable 

impacts on resident genetic 

resources 

● Socio-economic concerns: 

– clearly define and quantify 

the intended purpose of 

introduction 

– clearly identify and quantify 

the problem the proposal aims 

to rectify 

– clearly identify and quantify

alternative methods of 

addressing the same problem 

– identify and quantify the target beneficiaries 

– identify and quantify the non-target people at risk 

– assess the economic costs of undertaking the introduction itself 

● Pathogens 

– Minimizing the spread of diseases and parasites and quarantine 

arrangements 

The findings and advice should be communicated to the review panel, the 

introducing entity, and the decision-makers, after which all parties, including 

communities from the concerned area, will be given the opportunity to comment. 

The review panel comes up with its recommendation -- to accept, refine, or reject 

the proposal -- so that all parties understand the basis for any decision or action. 

Decision-makers will use the advice to make a decision. 

If the introduction of a species is 

approved, quarantine, containment, 

monitoring and reporting programs have 

to be implemented. 

Education 

Countries should endeavor to publicize 

and improve public awareness of both 

the issues involved in introductions and 

the procedures adopted to deal with 

such issues. 

Education should be aimed at all sectors, 

including fisheries and aquaculture 

managers and scientists in both public 

and private sectors, users of aquatic 

resources, especially business 

communities (who often have the most to 

lose from inappropriate movements yet 

are often the most vocal supporters of 

inappropriate introductions), as well as 

the general public. This reduces the 

incidence of unapproved introductions, 

and reduces the frustration of those 

Decision maker(s) 

This can be a person or group of 

persons with legal authority to 

decide whether or not an 

introduction can be made. 

References 

Bartley, D.M., R. Subasinghe and D. 

Coates. 1996. Framework for the 

Responsible Use of Introduced 

Species. European Inland Fisheries 

Advisory Commission, 19th session, 

1996. 

FAO. Technical Guidelines for 

Responsible Fisheries, 2. 1996. 

Precautionary Approach to Capture 

Fisheries and Species Introduction. 

Rome, Italy. 

Halwart, M. 1994. The Impact of the 

Golden Apple Snail (Pomacea 

canaliculata) on Rice in Asia: Present

whose proposals were denied. When 

people understand a rational system and 

think it is fair, they have less cause to 

complain, and are less likely to ignore 

regulations and agreements. 

For more information concerning the 

introduction of exotic species and the 

guidelines, please contact local authorities and 

The Asian Fisheries Society (P.O. Box 2725, 

Quezon City, Central Post Office, 1167 Quezon 

City, Philippines), the Chief of the Inland Water 

Resources and Aquaculture Service of the FAO 

(Viale delle Terme di Caracalle, 00100 Rome, 

Italy), or the Database on Introductions of 

Aquatic Species (DIAS): 

http://www.fao.org/fi/statist/dias/index.htm. 

Prepared by: 

Felix Marttin and Zubaida Basiao 

Impact and Future Threat. 

International Journal of Pest 

Management 40: 199 - 206. 

Philipp, D.P., J.M. Epifanio, J.E. 

Marsden and J.E. Claussen (editors). 

1995. Protection of Aquatic 

Biodiversity. Proceedings of the World 

Fisheries Congress, Theme 3. Oxford & 

IBH. Publishing Co. Pvt. Ltd., New Delhi, 

India. 

Sugunan, V.V. 1995. Exotic Fishes and 

their Role in the Reservoir Fisheries 

Regime of India. Fishing Chimes. April 

1995, India. 

Welcomme, R.L. 1988. International 

Introductions of Inland Aquatic 

Species. FAO Fisheries Technical Paper 

294. Food and Aquaculture 

Organization of the United Nations, 

Rome, Italy.

Primary Health Care in Aquaculture 

As in crop and livestock farming, a disease outbreak is considered one of the 

associated risks in aquaculture. Hence, the principle "Prevention is better than cure" 

is strictly followed to prevent disease-associated losses. However, aquaculture 

systems are more complicated, as the aquatic environment, which is relatively more 

dynamic than the terrestrial environment, plays an important role in the disease 

process and in determining the type and effectiveness of treatment and other 

management measures.

Aquatic animal health 

management includes steps to 

fight the three causes of 

diseases, namely: 

● pathogen 

● farmed animal’s 

susceptibility to diseases 

● environmental stress 

Primary health care emphasizes 

the first two aspects of health 

management. By resorting to 

simple and practical measures, 

the risk of disease outbreak can 

be minimized. Treatment 

measures to control and cure 

the disease is the last resort as 

they are complicated, 

expensive and, at times, may 

not succeed. Success depends 

on quick and precise diagnosis, proper selection of therapy, accurate calculation of 

doses, route and method of application, etc. It also requires expertise, skill and 

resources that small-scale farmers might not be able to mobilize. Primary health 

care, on the other hand, is simple and cost-effective and must be incorporated into 

farming practices. 

Management of rearing environment 

Management of rearing environment is the most vital area in disease prevention and 

control. It helps eliminate various stress factors to maintain the proper health of 

farmed animals as well as strengthen their defense system against disease-causing 

organisms. Management of rearing environment includes the following measures: 

Disinfection of pond 

Before initiating the farming operation, it is essential to disinfect the pond by draining 

and sun drying until the pond bottom cracks. If possible, the bottom should also be 

scraped and the upper portion of the sediment removed. As an alternative, certain 

disinfecting materials such as quick lime (200-500 kg/ha depending upon soil pH) or 

bleaching powder (25-30 kg/ha) may be applied over the freshly dewatered pond 

bottom and left to react for a week before refilling the pond with water. An interval 

of about seven to ten days between filling the unit with water and stocking should 

also be observed to eliminate most of the obligate pathogens (those that will not 

survive without finding a host) from the environment.

Commonly encountered environmental stressors 

Polluting agents (pesticides, industrial wastes, city sewerage, etc.) 

Algal toxins 

Toxic gases (ammonia, hydrogen sulphide, excessive free carbon 

dioxide etc.) 

Nitrite 

Abrupt changes in environmental parameters like temperature, pH, 

dissolved oxygen, salinity, etc. 

In the case of cage culture, it is important to disinfect the cage before and after 

harvesting. After the crop is harvested, the cage is lifted and thoroughly washed with 

quick lime solution and allowed to dry in the sun for two to three days. During the 

culture period, the cage should be cleaned once a week by wiping out all the dirt 

and wastes that remain. 

Eradication of wild fish and other aquatic animals 

Wild fish and crustaceans are potential sources of disease-causing agents. In case 

dewatering is not feasible, as with undrainable pond, certain safe piscicides are 

applied to the pond to eradicate the existing fish and other aquatic animals. Quick 

lime (1000-1200 kg/ha/m), bleaching powder (50-60 kg/ha/m), Mohua (Bassia 

latifolia) oil cake (2500 kg/ha/m), and tea seed powder (100-150 kg/ha/m) are some 

of the commonly used materials for this purpose. After the application of piscicides, 

the entry of fish and other animals into the pond should be prevented. As some fish 

eating birds and mollusks also serve as intermediate hosts for many parasites that 

infect fish and humans, care should be taken to keep the pond clear of vegetation 

that provide substrate for molluskan larvae. Introducing some species such as black 

carp or any native species of mollusk-eating fish helps prevent digenetic trematode 

infections to a considerable extent. Hanging wide meshed net over the pond 

prevents entry of birds. 

Selection of stocking materials 

It is advisable to stock only healthy and physically vigorous seed material to ensure 

better survival and growth. Before accepting the seed, know the source and 

reputation of the production unit in maintaining health and hygiene. Check the 

health status of the batch on a random sampling basis to avoid the risk of 

introducing infected stock. 

Some tips for selecting fish seed 

Desired Undesired

Vigorous and actively 

swimming 

Normal body color 

Soft to touch 

No sign of any patch, 

spot or 

lesion 

Fins - intact/complete 

Gills - deep red and 

without any 

sign of hemorrhage, 

spots or cysts 

Quick response to 

external stimuli such as 

tapping, touching, 

etc. 

Lethargic, abnormal 

swimming behavior 

Darker or abnormal 

color 

Rough to touch, 

excessive mucous 

secretion 

Appearance of 

discolored patch, 

spots, cysts, lesions, 

etc. 

Broken fin tips 

Tips on the selection of healthy shrimp postlarvae 

Discoloration/broken 

gill 

lamellae,appearance 

of hemorrhagic 

spots,cysts, etc. 

No or feeble response 

to external stimuli 

Actively swimming with straight body 

Dark color (gray, brown to black) with dark pigmentation in the tail area 

Red to pink color indicates sign of stress so the seed should be 

discarded. 

Normal shape of appendages and rostrum. Seeds that show black color 

and erosion of the appendages should be discarded. 

Quick response to external stimuli. 

Swimming against the current when the water of the container is stirred. 

When the current subsides, they cling to the sides to avoid being swept into 

the center of the container.

Selection of shrimp post larvae for stocking 

by conducting formalin stress test 

Take 2-3 liters of adequately aerated 

formalin solution (100 – 150 ppm). 

Introduce 150 randomly selected post 

larvae (PL) from the batch of seed to the 

solution and keep for 30 minutes (150 ppm 

solution without aeration) to two hours 

(100 ppm solution with aeration). 

Observe the mortality. 

Discard the seed if the mortality is more 

than 2%. 

Removal of dead fish 

Separation of young from brood fish 

Brood fish may serve as carrier of diseasecausing 

organisms without exhibiting any 

pronounced clinical symptom. 

Sometimes, they survive the occurrence 

of epizootics due to built-up immunity and 

may retain some pathogens. To avoid 

such risk, separate the young from the 

brood fish. 

The virulence of pathogens often increases with passage through the host. Remove 

dead fish and those specimens showing pronounced symptoms of diseases. 

Prevent overcrowding 

Overcrowding results in waste build up, decreased availability of space, feed and 

oxygen, and deterioration of water quality. Follow proper recommendations on 

stocking density for nursery, rearing and stocking ponds. 

Water quality 

Abrupt and wider fluctuations in some of the environmental parameters such as 

dissolved oxygen, pH, carbon dioxide, turbidity, etc., cause intense stress on the 

farmed aquatic animals. Some of the naturally generated toxic materials like 

hydrogen sulfide, ammonia and dinoflagellate toxins also often exceed the 

tolerance limit of the farmed animals and cause serious problems. Anaerobic 

condition of the pond bottom sediment may result in excessive production of marshy 

gases like methane, ammonia, hydrogen sulfide etc. Periodical raking of pond 

bottom at noontime, when the dissolved oxygen level is at its peak, helps aerate 

pond sediment, thereby reducing the formation of toxic gases. However, bottom 

raking is not advisable for shrimp ponds. 

Excessive application of fertilizers and the accumulation of nutrients in the bottom 

sediment induce the appearance of algal and bacterial blooms leading to 

dissolved oxygen depletion. To maintain proper health and optimum utilization of 

feed, the dissolved oxygen level should not drop below 3.0 mg/l in freshwater fish 

culture and 5 mg/l in brackishwater shrimp culture ponds. The toxicity of carbon 

dioxide, ammonia and hydrogen sulfide increases with the decrease in dissolved 

oxygen levels. Similarly, the toxicity of hydrogen sulfide increases with decreasing pH.

When pH values remain above 9 and below 6 species may survive but do not grow 

well. For shrimps, it is important to maintain the pH of the rearing environment 

between 6.5 and 8. Liming helps maintain the desired pH and also prevents daily 

fluctuations. Proper and timely management of soil and water by manipulating 

feeding, fertilization, liming, addition/exchange of water, aeration, etc., eliminate 

most causes of environmental stress. 

Proper feeding 

Any reduction in quantity and quality of feed may cause deficiencies or diseases in 

the fish or make them susceptible to infections. It is important to follow the 

recommended feeding rate for specific stages of farming. Feeding is more critical 

during the early stages (larvae and fry) of high density rearing when the availability 

of natural fish food is limited. Balanced feed, with desired levels of macro and 

micronutrients and vitamins, should be given to prevent diseases like lardosis, 

scoliosis, etc. Proper feeding also helps prevent cannibalism in catfish and shrimp 

culture systems. 

Note 

Proper handling 

Early morning (dawn) surfacing of fish and gasping for air indicate 

depletion of dissolved oxygen. 

In China, some farmers test the dissolved oxygen level by introducing 

some small fish known for their high oxygen demand. If the fish start 

surfacing 

soon 

after 

their 

release 

in the 

water 

being 

tested, 

the 

water 

must be deficient in oxygen. 

A moderate level of phytoplankton in both nursery and grow-out ponds 

must be maintained for better health of shrimp. Light green color indicates 

moderate level of phytoplankton. 

The rougher the handling, the greater is the stress and the risk of disease outbreak. 

Farmed aquatic animals should not be handled and transferred under hot weather 

conditions as high temperatures raise metabolic activity and place additional stress 

on the animals. In the case of fishes, care should be taken not to break the 

protective mucous coating of the skin.

Disinfection of net after its use in infected pond 

After using the net in an infected pond, be sure to thoroughly wash and dry it before 

use in another pond. It is also advisable to disinfect the net using disinfectants. 

Water supply and drainage 

In designing a farm, be sure to provide separate water supply and drainage facilities 

for individual ponds to avoid the flow of water from infected ponds into the other 

ponds. 

Disinfection of hatchery and other facilities 

All hatchery jars, troughs, tanks, utensils, tools, water holding and supply systems, nets 

and transport facilities should be thoroughly cleaned and disinfected before and 

after each hatching cycle to eradicate pathogens. Disinfection, through 

washing/emersion, can be done by using a concentrated solution of disinfectant. 

Some of the effective and commonly used disinfectants are chlorine, sodium 

hydroxide, salt, potassium permanganate, etc. Chlorine is probably the most widely. 

It is easily available in liquid form as sodium hypochlorite and in powdered form as 

bleaching powder. Solution of 1-2% chlorine is effective against bacterial, fungal 

and viral pathogens. However, it is also toxic to farmed aquatic animals, thus, 

disinfected items should be rinsed thoroughly of chlorine residues before use. 

Prophylactic measures 

Application of drugs and chemicals before the onset of a disease is very effective in 

preventing the outbreak of diseases. This method aims to eliminate pathogens, 

which may be in the host or the culture facility. Several methods are employed for 

chemoprophylaxis. Baths, oral and injection routes of administration of drugs are 

most common. Again, several types of baths such as dip, shot and long bath, flush, 

constant flow etc. may be used depending on the need, the availability of the 

facilities and the farmers’ own experience. 

Treatment of eggs 

Fish eggs may be treated by dipping in potassium permanganate solution (50-100 

ppm) for one to two minutes. Formalin is another commonly used therapeutant (250 

ppm). 

Treatment of fry/fingerlings 

It is important to acclimatize and treat the fry/fingerlings before stocking. Discard the

water and dip the fry/fingerlings in 1-2% of common salt solution or 50 ppm of 

potassium permanganate for one to two minutes before releasing them into the 

culture facility. Stocking should always be done during cool morning or evening 

hours. 

Treatment during sampling 

It is advisable to conduct periodical sampling, at least once a month, to check the 

health and growth of the seed. Periodical netting should be avoided during warmer 

parts of the day. Before the seeds are returned to the pond, they should be bathed 

in 50-100 ppm of potassium permanganate solution. 

Steps in pre-stocking acclimatization of seed 

1. Place the plastic bag containing seed material in the water of the 

culture facility and allow to float for 30-60 minutes. 

2. Add equal amounts of water from the facility where seed 

is to be stocked and keep for another 20-30 minutes. 

3. Give the seeds a prophylactic treatment before 

releasing them into the culture facility by dipping them 

either in salt or potassium permanganate solution. 

Treatment of broodstock

Give prophylactic treatment 

to shrimp/fish broodstock by 

bathing in 150-200 ppm of 

formalin for about five minutes 

before release. Other 

commonly available 

therapeutants like potassium 

permanganate (50-100 ppm) 

and common salt solution (2- 

3%) may be used as dip 

treatments (1-2 minutes) for 

fish brooders. 

Caution 

Handle formalin with care. 

Conclusion 

By following these practices, the outbreak of diseases can be avoided. As soon as 

there is a sign of any disease, it is better to consult a specialist for help in diagnosing 

the disease and for treatment and environmental measures. It is equally important to 

discuss the problem with neighboring farmers as an early warning. Measures can be 

taken individually and collectively to avert any larger catastrophe. If the disease is 

spreading fast and no immediate assistance is available, it is advisable, depending 

on size, to harvest the entire stock. 

Prepared by: 

Dilip Kumar 

P.P.G.S.N. Siriwardena

Fish as Biocontrol Agents of Vectors and Pests of 

Medical and Agricultural Importance 

Small-scale aquaculture in ponds and rice fields is generally 

considered valuable because of its contributions to food security, 

income generation and better nutrition for the farmer. However, it 

has been argued that an expansion of aquatic environments 

such as ponds or rice fields may also provide additional breeding 

grounds for various vectors of medical importance. At the same 

time, based on initial field observations, there have been studies 

examining the potentially beneficial role and contribution of fish 

to the management of pests in rice. Promising as well as 

disappointing results have been documented. This paper 

summarizes important findings, assesses the important reasons for 

success or failure, and provides recommendations on maximizing 

the positive impacts of aquaculture production and 

development. 

Fish as biocontrol agents 

Does small-scale 

aquaculture trigger an 

increase in vector 

numbers or contribute 

to their control? 

The most common fish species found in paddies and ponds include common carp 

(Cyprinus carpio), Nile tilapia (Oreochromis niloticus) and silver barb (Barbodes 

gonionotus). However, there are a large number of both stocked and additional wild 

fish species with potential for biocontrol in ponds and rice fields. 

Among these are larva-feeding and mollusk-feeding fish, which are of considerable 

importance in the control of vectors that cause human diseases like malaria and 

schistosomiasis. Other species of fish appear to be effective in controlling agricultural 

pests, for instance, common carp which consume a lot of immature golden apple snails 

and therefore directly impact the population dynamics of this rice pest. Some fish eat 

plants and, thus, help in weed control.

The effectiveness of fish in rice fields is hard to document and there is no evidence for 

an optimal rate for fish stocking density in pest control. High densities are presumed to 

be more effective. Understanding the role of fish in the rice field ecosystem is important 

if they are to be used as biocontrol agents, especially if they are introduced only for 

that purpose. 

Selected vectors of medical importance 

Insect vectors and related diseases 

Malaria 

● Caused by single-celled protozoan parasite of the genus Plasmodium; four 

species infect humans 

● Malaria is transmitted by the bite of the infected female mosquitoes of the genus 

Anopheles. 

Arboviral diseases 

● Transmitted by insects, e.g., Culex species that have previously fed on infected 

vertebrates (mammals or birds) 

● Aquaculture allows close contact between the virus’ original host, the vector, 

and humans. 

Selected control measures in pond and rice field aquaculture 

● Construction of steep banks 

● Removal of vegetation 

● Removal of small pools of water 

around the pond 

● Maintenance of rich biodiversity 

● Intermittently irrigation 

● Synchronous rice planting 

● Crop rotation (wet/dry) 

● Proper weeding 

● Biological control with fish: 

– larvivorous fish feeding on 

mosquito larvae; and 

– herbivorous fish feeding on 

vegetation. 

Assessment of biological control with fish 

For biological control it is 

important to understand the 

vectors’ ecology. Anopheles 

species breed in stagnant 

water bodies and sunny partly 

shaded pools of water. Several 

Culex species are found in 

marshes, ponds and ditches. When fish are 

stocked which not only inhabit the same 

environment, but also are known to feed 

on these vectors, the chances of successful 

biocontrol are good. 

Gambusia affinis, the so-called mosquito fish, is the most widely used species for this

purpose. In California rice fields, this fish is introduced each year shortly after fields have 

been flooded. The live-bearing Gambusia produces several broods during the summer 

months and an initial stocking rate of 750 fish/ha has given good results in the United 

States. Good results were also achieved in several other countries. 

As Gambusia has no economic value, the Chinese have tried to combine mosquito 

control and production of food fish. This dual-purpose rice-fish farming has been 

successfully practiced with common carp at a stocking rate of 8250 fish/ha. Anopheline 

and culicine larval populations were reduced by 90% and 70%, respectively. In 

Indonesia, a similar approach was followed. Fingerlings of food fish were given to 

farmers as an incentive so they would cooperate in the use of the guppy Poecilia 

reticulata, which had no food value, for biocontrol purposes. Good results in mosquito 

vector control have been obtained in Korea using indigenous fish species. 

Caution! 

Care should be taken that introduced fish do not replace indigenous 

fish by filling the same ecological niche. 

Not all mosquito species are equally controlled and the impact of 

introduced exotic fish on non-target organisms, including natural 

enemies of mosquitoes, may be significant. 

Combinations with other control measures are recommended particularly where fish 

seed is hard to obtain, e.g., a combination of stocking fish and applying Bacillus 

thuringiensis has been successful in mosquito control in India. 

Snail vectors and related diseases 

Schistosomiasis 

● In several Asian countries, 

Schistosoma japonicum is endemic. 

● In Africa, two forms -- urinary 

schistosomiasis caused by adult 

worms of Schistosoma 

haematobium and intestinal 

schistosomiasis caused by 

Schistosoma mansoni -- are found. 

● Eggs of the schistosome worms 

hatch when they come into contact 

with freshwater. Larvae infect 

certain species of freshwater snails 

(Oncomelania, Biomphalaria and 

Bulinus). 

● After multiplication, cercariae are

The life cycle of Schistosoma japonicum is 

complex and encompasses development in 

two hosts and two short-lived water-borne 

forms. When fish feed on these intermediate 

host snails the life cycle of the disease is 

interrupted. 

Ecological requirements of the snails 

released from the snails, which when 

they come into contact with 

humans, penetrate the skin and 

migrate to abdominal blood vessels. 

● Snails are generally aquatic, are found in shallow waters near the shore and slowmoving. 

They dry out when water levels fall and plant shelter is lacking. 

● They are highly tolerant of temperature differences. 

● Oncomelania snails are amphibious and prefer floodplain forests, swamps, 

waterlogged grasslands, stream, rice fields, irrigation canals, road ditches and 

borrow pits. 

Wetlands around the Mekong River in Southern Laos are inhabited by many 

different snails species. At least one snail Tricula aperta, acts as the vector for 

the parasite Schistosoma mekongi which can infect humans. 

Selected control measures in pond and rice field aquaculture 

● Construction of steep banks 

● Removal of vegetation 

● Proper water management 

● Screening of water inlets 

● Pond drying 

● Cleaning and lining of irrigation canals 

● Biological control of snails using fish 

● Use of molluscivorous fish feeding on snails and mosquito 

larvae 

● Use of planctivorous fish feeding on snail cercariae 

● Use of herbivorous fish feeding on vegetation 

Assessment of biological control of snails using fish 

Fish and crayfish may successfully control snails in ponds and reservoirs. Some fish 

species have specialized on snail feeding such as the black carp Mylopharyngodon 

piceus from China or various cichlids from Africa. The black carp has powerful 

pharyngeal teeth adapted to crushing mollusks and has been traditionally used in 

countries like China to control species of snails, which are nuisance organisms or 

intermediate hosts in parasite transmission.

Systematic studies on the performance of fish as snail eaters in water bodies are rare. 

After three years of observation, it was found that in rice fields in Katanga majority of 

snails were controlled by Haplochromis mellandi and Tilapia melanopleura, stocked at 

200 fish/ha and 300 fish/ha, respectively. The snail-eating ability of Sargochromis 

codringtoni, a cichlid, was successfully tested in laboratory studies in Zimbabwe. 

Good experimental results were achieved when the Louisiana red swamp crayfish was 

introduced into small rain-filled quarry pits to control the schistosome-transmitting 

Biomphalaria and Bulinus snails in Kenya. However, trials with another promising African 

cichlid, Astatoreochromis alluaudi, revealed that the fish were only successful at 

reducing snail populations if "there was nothing better to eat". Further investigations 

showed that the fish (from juvenile age one) need solid jaws to crush the snails but do 

not develop such jaws if they can find other, preferable foods. 

Selected pests of agricultural importance and their control 

Stemborers 

There is evidence of a lower incidence of 

stemborer damage when fish are stocked. 

Some recordings include: 

● In China, damage of the young rice 

plants (deadhearts) was reduced from 

0.37 to 0.33% with the presence of 

common carp and damage of the 

mature rice plants (whiteheads) from 

0.50 to 0.25%.

Others 

● In the Philippines, during a period of 

heavy stemborer infestation 

(between 10 to 20% whiteheads), 

damage was significantly reduced 

from 18% in the control (no fish) to 

13% and 15% with the presence of 

carp and tilapia, respectively. 

● In Indonesia, when an outbreak 

of stemborer was predicted, 

farmers and their families went to 

the fields and collected the egg 

masses manually to control the 

stemborer populations. Such flexible 

approaches are needed for 

exceptional years. 

There are several reports documenting 

either reduced numbers of agricultural 

pests or less damage caused by pests 

and diseases with the presence of fish. 

The pests include gall midges, 

caseworms, brown and whitebacked 

plant hoppers, sheath blight, brown spot 

and bacterial blight. Most of the work was 

done in concurrent rice-fish systems. In 

some cases, the underlying mechanisms 

were described. The control effect 

generally was the result of direct feeding 

by the fish when pests came into contact 

with the ricefield water during one of their 

development stages. Golden apple snails, for example, fall into the water immediately 

after hatching on the rice stem, planthoppers try to escape the predatory attack of 

spiders by letting themselves fall into the water surface then climbing back on to the 

plant, and stemborer larvae disperse by floating on the water to reach uninfested rice 

hills.

Observations from the field on the biocontrol of snails using fish 

When common carp was stocked in Philippine rice fields, where there 

were large numbers of the golden snail (an introduced aquatic pest of rice 

in Asia) there was an observed sharp decrease in the snail population. 

When using tilapia on snails, increasing the stocking density can 

compensate for their poor feeding efficiency. 

Predation depends upon the size of both fish and snails, and larger snails 

have a higher probability to escape predation. 

C. carpio consumes the small snails so the number of big snails 

may increase in rice fields stocked with carp. Additional manual 

control measures will be needed (initially) for the big snails as 

these are most damaging to the rice crop. 

Vector control using fish will be more effective if the following are 

taken into consideration 

Choice of fish species 

Each fish species has a distinct feeding habit, which may be useful for biocontrol 

purposes. Indigenous fish fauna should be screened for this purpose. 

Fish density 

Fish density becomes more important when the fish species are less efficient in eating 

and controlling a particular organism (the fish would prefer to eat organisms other than 

the disease-causing organisms). This is particularly true in the case of small vectors such 

as chironomid, mosquito and stemborer larvae or juvenile snails. However, high stocking 

densities affect fish growth and harvesting small fish may discourage farmers. This 

practice is therefore suggested for areas where ponds and rice fields are used as fish

nurseries and fish grow-out operations demand a regular fingerling supply. 

Fish size 

Size is important when vector can outgrow predation. It is suggested to stock bigger fish 

in areas where golden snails are a problem. 

Conclusion 

Farmers cannot be expected to stock fish in ponds or rice fields 

for public health reasons only. A promising concept is to use fish, 

which can later be harvested for food. Nile tilapia and common 

carp have been introduced and established for food fish 

farming in many countries. Where social acceptance favors 

tilapia, polyculture is suggested. 

Well-maintained aquaculture operations do not increase but rather contribute, often 

significantly, to the control of insects and snails of agricultural and medical importance. 

Vector populations can exhibit changes in life history. Traits may change in response to 

predation. Therefore, the complete elimination of a target organism by fish cannot be 

expected. Biological control should not aim at the eradication or elimination of an 

organism. Rather, integrated vector control and integrated pest management 

programs should be pursued where vector populations are managed so they do not 

cause significant problems. 

Prepared by: 

Matthias Halwart

Possible Public Health Hazards Associated with 

Farmed Fish and Shellfish 

Aquaculture system is a confined system. In spite of the best environmental 

monitoring and control measures, several types of contamination are likely to take 

place in farmed fish and shellfish. 

Importance of aquaculture 

Most of the developing countries contributing significantly to 

aquaculture production are situated in the tropics and 

subtropics and most of the information available on the hazards 

and public health aspects of fish and fishery products 

concentrate mostly on the marine fish and fish products of 

tropical waters. Information on hazards associated with 

aquaculture products from warm waters is sparse. 

Microbes and parasites 

Food-borne diseases mostly come from consumption of fish infected by pathogenic 

bacteria, viruses or parasites. However, these become significant only when raw or 

inadequately cooked fish is consumed. Trematode parasites that can cause illness 

ranging from debilitation to cancer or even death are the most important. Infection 

caused by such parasites is found in geographical areas where they are endemic in 

the natural fish population. 

Hazards associated with culture system

Infection by food-borne trematodes 

Infection by pathogenic bacteria, viruses or parasites 

Contamination by agro-chemicals used for pest control 

Contamination by residues of growth promoters, antibiotics, veterinary 

drugs, etc. 

Contamination by heavy metal residues 

Bacterial contamination, especially by the pathogenic species, is a potential hazard 

in aquaculture systems. The level of contamination of farmed fish and shellfish will 

depend greatly on the bacterial quality of the water body as well as the 

environment. Proximity to human habitations can result in increased levels of 

contamination by several pathogenic bacteria as well as fecal indicator organisms. 

Contamination by the bacterial population naturally present in the environment 

such as Aeromonas hydrophila, Clostridium botulinum, Vibrio cholerae etc. is also 

common. Bacterial flora such as Salmonella sp., E.coli, Entrobacterieae, Shigjella also 

show up because of contamination by human waste/animal excreta. The latter 

species can get introduced into an aquaculture system, even through birds or 

animals. 

Bivalves as pollution indicators 

Molluscan bivalves such as clams, mussels and oysters are 

considered indicators of environmental pollution by bacteria and 

heavy metals. They are filter feeders and accumulate such 

contaminants in their internal organs. Hence, they present a 

potential threat to the health of the consumers much more than 

crustaceans or finfish. The level of these pollutants in bivalves 

available from an area can give a clearer idea about the extent 

of pollution. Paralytic shellfish poisoning (PSP), diarrheic shellfish 

poisoning (DSP) and amnesic shellfish poisoning (ASP) are also risks 

associated with molluscan bivalves, whether from cultured or wild 

source. 

Pest control chemicals 

The pest control measures in culture systems employ chemicals to treat the fish as 

well as control diseases and pests. The residues of such chemo-therapeutants, if 

employed indiscriminately, can become a potential source of danger to consumer’s 

safety.

Antibiotic residues 

Hazards associated with culture system 

Another threat to consumers comes from the residues 

of antibiotics used to control fish diseases and residues 

of growth promoters used in the feed. Many 

organisms may become resistant to antibiotics. 

Humans infected by such antibiotic-resistant 

organisms find treatment complicated. 

Infection by food-borne trematodes 

Infection by pathogenic bacteria, viruses or parasites 

Contamination by agro-chemicals used for pest control 

Contamination by residues of growth promoters, antibiotics, veterinary 

drugs, etc. 

Contamination by heavy metal residues 

Toxic chemicals from industrial effluents 

Another problem in cultured products is the contamination caused by industrial 

pollutants and agro-chemicals. Heavy metal type industrial pollutants are not 

considered a very significant risk in aquaculture but contamination by 

polychlorinated hydrocarbons and similar highly chlorinated industrial chemicals 

poses a real threat to cultured products.

As with any other 

human activity, 

hazards and risks which 

may adversely affect 

human health, are 

inherent in 

aquaculture 

production. Cultured 

fish and shellfish should 

therefore be handled 

and processed 

carefully. 

Prepared by: 

K. Devadasan and K. Gopakumar

Improved Handling and Quality Assurance of Fish 

and Fishery Products 

Aquaculture, whether in freshwater, brackishwater or coastal marine waters, 

appears to 

be the only viable solution to the growing demand for fish. Production alone, 

however, is not enough. Proper handling, transportation, processing and marketing 

are also essential to ensure the judicious and profitable use of farmed aquatic 

resources. 

Handling of harvested fish 

Proper pre-process handling is very impo rtant to ensure 

quality. Fish must be handled properly because it is a highly 

perishable food susceptible to contamination by 

pathogenic bacteria. Depending on the species, there are 

various enzyme systems, which can play a vital role in 

causing spoilage. An understanding of the activity of the 

bacteria and enzymes is essential to retard spoilage. 

Causes of fish spoilage

Shrimp 

Bacterial action 

Enzyme action 

Oxidative reactions 

involving fat that cause 

rancid flavor 

Shrimp are important species for 

culture, as they give good returns 

to the farmers. Shrimp harvested 

from the wild come from unknown 

stock. Likewise, wild sources may 

contain a mix of species with 

different sizes and stages of growth. 

Farmed shrimp, on the other hand, often belong to the same species, can be reared 

to desired level of growth and can be harvested according to a predetermined 

schedule. The delay between harvesting and processing may cause the loss of some 

intrinsic qualities of the shrimp. Cultured shrimp is often packaged individually in 

quick frozen (IQF) form that gives more returns and value to the shrimp as a product. 

Microbiological quality 

Around 30% of the frozen shrimp processed out of traditionally farmed species 

contained salmonella and other pathogens, whereas similar incidences were 

observed in only 10% of the samples processed out of their marine counterparts. It 

was also observed that among the cultured species, the bacterial load was higher in 

the traditionally farmed shrimp than those cultured in intensive systems even though 

the former had low stock density and no supplementary feeding, pond fertilization, 

and aeration. The bacterial load of shrimp farmed in the intensive systems was lower 

because of the scientific approach to pond management. 

It is recommended to keep the shrimp in ice-cold water containing 5 ppm chlorine 

(allowing a contact time of five minutes before packaging and transport) 

immediately after harvest to improve its quality.

Soft shell 

Shrimp generally molt at night when food, 

temperature and light conditions are 

satisfactory. Shrimp shell generally contains 

protein, calcium compounds, particularly 

calcium carbonate, chitin and fat. Prior to 

molting, considerable amounts of protein 

and chitin as well as negligible amounts of 

calcium carbonate are withdrawn from the 

shell as new shell forms underneath. The 

entire shell is replaced and the new shell is 

almost hard after five hours. If the shrimp is 

harvested without allowing enough time for 

the hard shell to form after molting, the crop 

may contain several soft-shelled specimens. 

The high calcium content and the thinness of the shell make the shrimp vulnerable to 

damage by acidic components (ascorbic acid, sodium bisulphate) as well as 

physical damage. Soft-shelled shrimp may also harbor a higher bacterial load. 

Handling and transport 

Farmed shrimp is very delicate 

and is best suited for processing 

as whole IQF products. 

Therefore, the handling 

practices should ensure that no 

damage occurs. Increased bulk 

density and height of package 

may result in loosening the 

head and damaging the shell. 

Such incidents will worsen if 

crushed ice is used. Higher 

packing density is also known 

to cause white patches in 

cultured shrimp processed in frozen whole, cooked whole or headless styles. A pack 

height not exceeding 30-35 cm is recommended and flaked ice should be used 

instead of crushed ice. The shrimp should be covered with sufficient quantity of ice 

so that the melted water forms a film over the shrimp and prevents oxygen from 

coming in contact with the material. The surfaces on which the shrimp is placed and 

the hands of workers handling the shrimp should be clean.

Blackening and prevention 

Shrimp should be transported in 

refrigerated/insulated vehicles. 

If facilities for chilling are not 

available, sufficient quantity of 

ice should be ensured. If the 

location of the processing 

plant is far from the culture 

area, facilities for augmenting 

ice supplies should be 

arranged en route. Sturdy 

containers should be 

employed to avoid damage 

during transport. 

Blackening, though not a serious problem in farmed shrimp, may take place if the 

shrimp is held for longer periods without ice and if the duration of transport under ice 

is unduly long. As a precautionary measure, ice should be applied (preferably flaked 

ice) after harvest and/or the shrimp should be dipped in 0.4% sodium metabisulphite 

solution (for a contact period of 30 seconds). 

Processing and storage 

Freezing 

An important method of cultured shrimp preservation is by individually quick freezing 

in whole/headless or cooked form. Other value-added products such as battered 

and breaded shrimp can also be processed out of farmed shrimp. Frozen materials 

other than battered and breaded types are given a protective glaze coating and 

appropriately packaged and stored at -20°C or below. 

Canning 

Cultured shrimp, when canned, generally yield a very soft product. Treatment with 

chemicals, partial drying or mild smoking after blanching is found effective in

ensuring a soft and firm texture. 

Live transport 

Important species of finfish that are transported live are 

the carps, salmonids and tilapias. Catfishes are also 

transported live in Thailand. The market for live fish is 

increasing, perhaps influenced by cultural preferences 

and growing affluence. At present, such markets are 

becoming predominant in countries like Singapore, 

Malaysia, and China. Expansion into other places is 

indicated. Therefore, transportation of fish in live form is 

emerging as an important method of post-harvest 

handling. The transport requirements may vary with 

individual types of fish depending on whether they are 

of marine or fresh water origin. Transportation generally 

employs the tank method, which is suitable for bulk 

transport of live fish. The method involves shipping live 

fish in boats or tankers. Tanks are often equipped with 

circulation and aeration systems. The circulated water is 

aerated before feeding it back to the tank. Water can 

hold more oxygen at lower temperatures. Fish, however, 

require more oxygen at higher temperatures. A tank of a 

given volume can, therefore, hold more fish at lower 

temperatures than it can at higher temperatures. 

Therefore, the temperature of water in transport tanks is 

always kept low, but at levels the fish species concerned 

can tolerate. Fish with empty guts transport better. 

For finfish, live transportation is 

an important method. It is 

extensively practiced in 

China, Thailand and 

Malaysia. 

However, in the case of high value products like shrimp, transport in polythene bags 

containing water and oxygen is increasingly practiced, particularly in transport by 

air. Finfishes are more prone to enzymatic problems. But it depends on species 

because the nature of enzymes varies from fish to fish. Maintaining low temperature 

helps to reduce bacterial as well as enzymatic action. Exclusion of oxygen by 

keeping the fish in chilled water reduces fat oxidation 

problems also. 

Freezing preservation 

Most of the cultured species of fish are suitable for freeze preservation. Air blast or 

spiral type freezers are the most suitable type for these fish. It is better to process 

them as IQF, chunks or fillets. It is advisable that the fish, (whether whole, chunk or 

fillet) are glazed and individually wrapped in polythene paper before cold storage. 

The fish fillet can also be processed into value-added battered and breaded

products. However, fillet are skinned and treated with a dilute solution of sodium 

chloride before battering so that the color, flavor and taste are improved. 

Some types of fish like carp have bones in the flesh, which adversely affect eating 

quality. Even though fillets of good size and shape can be made out of them, they 

cannot be processed as battered and breaded products. Processing fish mince by 

getting rid of the bones, using bone separators, is a better way of utilizing such fish. 

The mince prepared from cultured fresh water fish such as catla (Catla catla) and 

rohu (Labeo rohita) has been successfully used in preparing value-added products 

like battered and breaded fish fingers, burgers, cutlets, that are now popular items in 

the fastfood trade. Likewise, other low value fishes have been used in producing 

sausages and paste products although farmed fish are not used much for these 

purposes. 

Canning preservation 

When canned, the meat of farmed fresh water fish like rohu becomes very soft. In 

order to enhance texture, treating the fish fillet with 15% brine containing 0.25% 

calcium chloride prior to canning is found useful. 

Bivalves 

Bivalves are known to accumulate pathogenic 

bacteria and heavy metals in their internal organs 

due to their filter feeding habit. Being filter feeders, 

their stomach at any time may contain gritty 

materials like sand. Therefore, it is a pre-requisite that 

these animals are biologically cleansed before they 

are processed or consumed. One of the best and 

easiest methods of biological cleansing is to depurate 

them by starving in clean water from their natural 

habitat. By doing so, the grittiness can be brought down to non-detectable levels 

and the bacterial quality improved by freeing them of all pathogenic bacteria. 

Whole mussel as well as meat shucked from fresh mussel yielded 

the best products. However, whole mussel stored under ice for two 

days also yields meat suitable for canning. Other preservation 

processes applicable for mussel meat are smoke curing, drying 

and marinating. Washing the meat of cultured edible oyster in 5% 

brine containing 0.1% acetic acid is considered a necessary pretreatment 

to avoid formation of lumps and to yield meat with soft 

and firm texture. Processing clam meat in pickled form has been 

found to be economically viable. The pickle can be made to suit 

the taste of the intended market.

Quality assurance 

Aquaculture is an important sector that contributes substantially to fish production. 

Though majority of the produce is consumed domestically by the producing nations, 

there is a significant increase in their processing for export. Because of the inherent 

health hazards and the regulatory requirements of the importing countries, strict 

observation of quality measures becomes important in the production, harvesting, 

handling and processing of these fishery products, whether it is for internal 

consumption or export. 

HACCP is a quality assurance concept established 

by the quality conscious affluent importing nations of 

the West. The possible hazards that can cause 

quality problems, and their control points in the chain 

of processing operations are identified and listed first. 

The critical control points are then identified to 

ensure the quality of the finished product. Constant 

monitoring and documentation of identified 

parameters and strict management of the critical 

control points will ensure quality of the finished 

product. The earlier "quality control" concept, which 

involves inspection and acceptance or rejection of 

the end product, has given way to "quality assurance", ensuring 

maintenance of quality at every stage from harvesting to handling, 

transportation, packaging and marketing. Hygienic handling, use of high 

quality water for processing, etc are all part of this concept. The system is 

already revolutionizing fish processing, which is at last beginning to be 

treated as a high-tech industry dealing with a perishable food item. 

The hazard analysis critical control point (HACCP) approach has to be applied for 

cultured products, from culture to consumption, to avoid risks associated with 

consumption of such fish and shellfish. Most of the hazards associated with fish 

processing have been detailed above. However, systems may have to be 

developed separately for the culture and handling of each fish and shellfish 

because the environment and habitat of the species under culture are different. 

Development and application of HACCP based quality assurance program in the 

culture may not be very difficult in commercial large-scale operations. However, 

there are a vast number of small holdings under aquaculture, which mainly aim at 

distribution of the fish for domestic consumption. Operational limitations of such small 

systems of aquaculture may impede the development and adoption of proper 

HACCP based quality assurance programs. 

Prepared by: 

K. Devadasan and K. Gopakumar


Participatory Approaches and 

Extension Strategies 

Participatory Approaches for 

Aquatic Resources 

Management and 

Development: Thoughts and 

Lessons Collected by DFID 

and FAO during 2000 

Scaling Up the Impact of 

Aquaculture: The CARE 

Experience in Bangladesh 

Scaling Up the Impact of 

Aquaculture: AquaOutreach 

at Asian Institute of 

Technology 

Participatory Approach to 

Extension and Training in 

Aquaculture 

A "Farmer Field School" for 

Aquaculture 

Aquaculture Development 

and Information Processes 

Rural Aquaculture 

Development and Mangrove 

Conservation Projects 

(Initiated by Fishers in 

Collaboration with Various 

Institutions in Sri Lanka) 

Use of Geographic 

Information Systems (GIS) 

for Planning and Management 

of Aquaculture 

Participatory Approaches and Extension 

Strategies

Participatory Approaches for Aquatic Resources Management 

and Development Thoughts and Lessons Collected by DFID and 

FAO during 2000 

Aquatic resources management in the context of poverty is not limited to a 

particular technology or to different forms of aquaculture. It also includes the 

concentration and capture of wild fish and the foraging of aquatic resources such 

as crabs, prawns, snails, insects, aquatic plants, etc. in paddies and other water 

bodies. Many of these activities remain invisible to researchers and rural developers 

because dispersed and small-scale production data, which are difficult to collect by 

conventional approaches, do not appear in official statistics. As the emphasis in 

aquaculture development now shifts from purely technical to extension and poverty 

alleviation issues, there is a considerable need for more widespread application of 

participatory approaches. 

The term "participatory approaches" is used to describe a wide range of 

development and research approaches, methods and tools that can improve the 

practice of development. Relatively novel approaches include the consideration of 

aquatic resources management in the context of livelihoods, working with poor 

aquatic resource-users, building on their strengths in the context of environmental, 

social and economic issues that impact on their livelihood strategies. Much can be 

learned not only from recommendations based on knowledge generated, but also 

on the methodologies used. 

Guiding principles of participatory approaches

Participatory approaches might best be described as a 

set of "guiding principles" that can help practitioners 

develop a different kind of relationship with the people 

that are supposed to benefit from their work. The guiding 

principles that really make up participatory approaches 

were reviewed in the FAO Fisheries Report No. 630 

(2000). 

Guiding Principles of participatory approaches 

Organized process While participatory approaches make use of a flexible "basket" of different methodologies, 

those methodologies are guided by objectives and responsive facilitation. 

Systemic learning 

Multiple 

perspectives 

Group learning 

Context specific 

Facilitating 

The methods used in participatory approaches emphasize learning about systems and the 

relations between different elements in those systems. Participatory approaches need to be 

"holistic". 

Participatory approaches take into account the fact that different people have different 

perspectives and try to accommodate these different perspectives. 

Participatory approaches emphasize the value of learning in groups as a means of coming to 

consensus decisions regarding action to address commonly identified objectives. 

(Understanding the "group" and the power relations within the group is important so that 

"consensus" decisions reflect the needs of weak group members as well as the strong ones.) 

Each community and its context are different. Participatory approaches accommodate their 

specific characteristics. (From experience, the importance of recognizing the differences 

within communities, and between social and economic groups, is also being emphasized more 

and more.) 

The use of participatory approaches by development practitioners involves the adoption of a 

facilitating or catalytic role, rather than a protagonists. 

Leading to change While participatory approaches accommodate local knowledge and skills, they are focussed on 

facilitating changes that people regard as appropriate. 

The terms for participatory approaches and methodologies are as numerous as the 

locations where they have been put into practice. Being "context specific", there 

can be no "blueprint" for participatory approaches. They need to be constantly

adjusted, refined and adapted based on the local setting. 

A selection of participatory methods and their uses 

Participatory Brief description 

Timelines 

Seasonal calendars 

Transect walks and through 

particular areas 

Social maps 

Historical profiles of longer-term 

events or trends 

Graphical representation of 

seasonal events or trends 

Land- and water-use maps 

based on walking capital, local 

knowledge of microhabitat, 

current use of aquatic resources 

Maps locating key social 

features 

Wealth ranking Socio-economic categorization 

of households 

Preference ranking 

Ordinal ranking, e.g. based on 

pairwise comparisons, based on 

defined criteria with scoring 

Examples of particular use 

method 

Fish catch over time, 

productivity changes, policy 

changes 

Labor availability, 

hydrographic changes 

Quality and quantity of natural 

resource maps 

Access to services and 

infrastructure 

Assets, income 

Livelihood strategies, assets 

and matrix ranking access to 

services (e.g., fish for 

conservation)

Adaptability has led to a large number of variants in participatory approaches. This 

means there can be no single definition of what constitutes a "participatory 

approach". What is important is that the approach and methodology have been 

planned systematically, bearing in mind the guiding principles of participatory 

approaches. The following are two different examples of these approaches: 

1. 

Experiential learning in farmer field schools in rice creates opportunities for the 

integration of aquaculture 

● The approach to reach and enhance human expertise for better rice crop 

management, particularly in relation to integrated pest management (IPM), is 

via farmer field schools (FFS) with about 25 farmers each. Farmers in 

Bangladesh, Indonesia, Vietnam, Cambodia, Ghana, Burkina Faso, Mali, Côte 

d’Ivoire spend 5-6 hours together every week. Two hours are spent in the field 

observing the ecosystem. The process is facilitated by trainers, who themselves 

have spent a whole season in the field learning about the ecosystem and 

designing curricula for the FFS. 

The approach described here is from the FAO’s Intercountry Program on Integrated Pest 

Management in Rice in Asia and draws much from the experience gained in the 

implementation of the National IPM Program in Vietnam. 

Source: Kenmore, P. and M. Halwart. 1998. Functional agrobiodiversity, Integrated Pest 

Management, and Aquatic Life Management in Rice. In: Proceedings of the FAO/CBD 

International Workshop on Opportunities, Incentives, and Approaches for the 

Conservation and Sustainable Use of Biological Diversity in Agricultural Ecosystems and 

Production Systems. FAO, Rome, Italy. 

● The equipment needed in FFS are plastic bags, pencils and paper. Farmers put 

samples of arthropods in plastic bags and after the field work they discuss in 

small groups what they have observed, prepare poster diagrams, and present 

findings to their fellow farmers.

● Farmers observe populations in 

the field but also test their trophic 

linkages by setting up "insect 

zoos". These answer questions on 

"what eats what" and "how many 

are eaten", etc. Such experiments 

are interventions that advance 

farmers’ knowledge and lead to 

further experimentation. 

● Elimination of nearly all pesticides 

results in a higher biodiversity, 

which is frequently used by 

farmers in a sustainable manner. Snails, frogs, aquatic insects and others 

constitute an important part of the diet of many rice-farming households. 

Where wild aquatic resources are declining from habitat change then 

culturing fish in rice fields or adjacent water bodies becomes increasingly 

important. 

● Farmers’ advanced knowledge about rice field biodiversity, together with 

vastly reduced pesticide levels, opens new opportunities for food security and 

income generation; many rice farmers decide to double the use of their fields 

and the rice field aquatic ecosystem by raising fish. 

● They experiment with different management options, growing a "crop" of fish 

together with the rice in the same field, using the field to grow a crop of fish 

between two rice crops, or growing fish after rice instead of a second rice 

crop. 

● Farmers experiment with physical modifications of the fields to accommodate 

the fish such as digging trenches in different shapes and sizes or small ponds at 

different locations. They are innovative in adapting their production systems to 

local market conditions – growing bigger fish for sale or their own consumption 

or smaller fish, if they can sell them to grow-out operations nearby. 

● Better utilization of resources, increased income, and a healthy crop of rice 

and fish reinforce farmers’ acceptance of integrated pest management and 

rejection of pesticides. Experience shows that many groups of farmers decide 

to continue the process of information exchange in self-organized "farmer 

clubs" long after the FFSs have ended. 

2. A participatory approach to aquaculture research and development in Laos 

● The Lao People’s Democratic Republic is very poor, and people depend heavily on the natural 

resource base, especially rice and fish consumption. The Provincial Livestock and Fisheries 

Section (LFS) provides support services including extension. It was anxious to become better

equipped to fulfill its role. The UK researchers and the LFS agreed to develop 

recommendations together with the farm families who might use them. A participatory 

situation analysis was conducted in which LFS staff identified and characterized eight different 

rice paddy agro-ecosystems that could incorporate fish. 

Experiences from a DFID research project coordinated by the Aquaculture 

Research Program, managed by the Institute of Aquaculture, University of 

Stirling and carried out in collaboration with the staff from the Livestock 

and Fisheries Section (LFS), of Savannakhet Province, Laos, the Lao 

Women’s Union (LWU) and the AIT Aqua Outreach Laos project. The 

research aimed to address technical, social and economic constraints to 

rice fish culture in Laos. 

Source: Haylor, G., A. Lawrence, E. Meusch, and K. Sidavong. 1999. 

Addressing technical, social and economic constraints to rice field fish 

culture in Laos, emphazising women’s involvement. Final Technical Report 

DFID ARP Project R6380Cb. 

With institutional strengthening support from AIT Aqua Outreach Laos and Stirling 

University, the LFS set up a formal procedure for formulating, recording, monitoring 

and upgrading recommendations, using the rice-fish recommendations as a testcase. 

Special forms (for recommendations and trials) were discussed and 

developed by LFS staff. A key change is that the district staff now records the 

recommendations they make in response to farmers needs. If a recommendation is 

a best-guess option (not the result of testing by farmers or other research), it is 

recorded as a trial and monitored. Recommendations and trials are discussed 

annually at village-based workshops so that an iterative process exists to upgrade 

and refine promising recommendations and discard or amend those that fail. 

● To assess the wider implications of 

the recommendations, the Lao 

Women’s Union developed 

indicators and a system of 

participatory monitoring and 

evaluation. Members of the farmhousehold 

compare their 

perceptions of the farming system 

before and after. 

● This case highlights a novel 

mechanism, which encapsulates 

different roles for the key players 

and devolves the research and 

development process to farmers 

and field workers. It values local 

knowledge while acknowledging 

the role of outsiders and focuses on identifying and characterizing different

ecommendation domains. Sustainable impact is attempted by instigating an 

iterative process that leads to the documentation and refinement of the 

existing system of research and development support at a rate consistent with 

local capacity. 

● The process is considered relevant to countries with developing economies 

that are characterized by NR research and development institutions at an 

early stage of development, with limited communication with the communities 

they have to work with, and where standardized or single technical 

recommendations are commonplace. It applies particularly to the 

communities that manage diverse, risk- prone natural resource systems. 

Lessons learned 

Significant lessons have been learned from participatory approaches related to 

aquatic resources management during 2000. Below lists learning gained as 

presented in an FAO workshop on participatory approaches used for aquaculture 

development held in Bangkok in March 2000. The issue of learning and 

communication processes also featured prominently in the recent E-Mail 

Conference on Aquatic Resources Management for Sustainable Livelihoods of Poor 

People in the SE Asia, in July 2000 (see related topic on Aquatic Resources 

Management for Sustainable Livelihoods of Poor People, page 11). 

Clearly there can be no definitive "conclusion" regarding the appropriateness of 

using participatory approaches in aquaculture but the points listed below can be 

taken as issues and, in some cases, indicators that can help people decide how to 

incorporate participatory approaches into their work. 

● The use of participatory approaches in aquaculture development activities 

can add value to those activities. During the research phase, they can ensure 

a better understanding of a wider range of issues and the context in which 

aquaculture is being considered or applied. They can also help ensure that 

aquaculture development addresses real issues and needs of potential users. 

During the implementation phase, they can ensure better implementation and 

better monitoring of impacts. 

● Participatory approaches cannot be applied across the board to all types of 

research at all stages. They can make an important contribution to the 

identification of the research subject by helping researchers understand what 

the problems and priorities of potential users are. However, some forms of 

"basic" research are better carried out in a "non-participatory" way as 

participation by people in the field, particularly the poor, may expose them to 

increased risk. Once the results of basic research have been established, 

participatory approaches are an essential part of the adaptive research, 

which needs to refine solutions and make them appropriate to local 

conditions.

● In the implementation of aquaculture development activities, participatory 

approaches are important in ensuring that activities are implemented in an 

appropriate way and can increase the sustainability of activities by giving 

users the leading role in developing and adapting new activities. But 

participatory approaches require different forms of management compared 

to more "traditional" or top-down approaches. They require changes in skills 

and attitudes among those involved in aquaculture development, which 

require time. 

● The adoption of participatory approaches, and the specific approaches used, 

need to take into account the capacity of the institutions and practitioners 

involved. Familiarity with the principles of participation, an acceptance of 

adaptive management of field activities, good planning and decentralized 

decision-making are all important in effectively supporting participatory 

activities. Time and resources have to be devoted to developing these skills 

and capacity. 

● The adoption of participatory approaches is not a panacea. It does not make 

other approaches unnecessary nor is it always the best approach in all 

situations. The costs and benefits compared to alternatives need to be 

carefully assessed. 

Learning and communication processes are important in enhancing the 

capability of poor people to manage their resources. This issue featured 

prominently in the recent DFID SE Asia Aquatic Resources Management 

Programme E-Mail Conference. (See related topic on Aquatic Resources 

Management for Sustainable Livelihoods of Poor People) 

● Participatory approaches in aquaculture have been used primarily to contribute to research. 

Their use as a means of improving understanding of conditions, problems and issues is 

important but, by concentrating on participatory research, some of the wider potential of 

approaches may be missed. The real potential of participatory approaches lies not just in the

improvement of aquaculture development workers’ knowledge, but in the building of the 

capability of the end-users to make decisions about aquaculture and its place in their livelihood 

strategies. This area of application of participatory approaches needs to be further developed in 

the aquaculture sector. 

Prepared by: 

Matthias Halwart and Graham Haylor

Scaling Up the Impact of Aquaculture: The CARE 

Experience in Bangladesh 

Aquaculture is contributing significantly to the total fish production of Bangladesh. To 

increase production from the aquaculture sector, it has been suggested that major 

shifts in extension strategies are necessary. The agriculture and natural resource 

sector of CARE-Bangladesh has been exploring alternative approaches to develop 

extension systems appropriate to the needs of small farmers. The processes 

experimented in promoting aquaculture development with small and marginal poor 

farmers have resulted in improved productivity from the different systems. The 

experiences gained in scaling up the impact of aquaculture indicate that to 

empower farmers and sustain development, it is necessary to change the focus of 

extension systems from technology transfer to helping farmers understand the 

principles and processes. With the knowledge acquired, farmers should be 

encouraged to develop by themselves systems appropriate to their farm using their 

own resources. 

Why scale up the practice of aquaculture? 

Aquaculture has been recognized as one of the activities that can have a 

significant impact on the livelihoods of the people and bring measurable changes. 

Scaling up such an activity would help in the efficient use of unused water resources 

or to improve existing practices, so that more people can derive benefit quickly from 

aquaculture and sustain the activity.

Research results obtained from partnerships with farmers were found to have 

substantial benefit to the farming community chosen for pilot scale testing. Based on 

the results obtained from the pilot phase, necessary adjustments were made for 

scaling up. Farmers are kept at the center in deciding what is appropriate for scaling 

up and sustaining the program. 

Magnitude of scaled-up activities 

On average, about 40,000 families annually are covered by a direct 

delivery system, where CARE extension staff directly work with farmers. 

Among these farmers, 20-30% only are generally involved in aquaculture 

activity, particularly rice-fish cultivation. There are six projects funded by 

DFID and European Union, with aquaculture as one of the components, 

and these are spread all throughout Bangladesh covering several hundred 

villages. Coverage through partnership is gradually increasing. Partnerships 

have been established with more than 150 NGOs and CBOs for the 

implementation of the activity either on contract basis or collegiate basis. 

Working through partners has different dimensions from working directly 

with farmers. 

CARE-Agriculture and Natural Resource Program principles 

● Focus on people and not on technologies. Understand the livelihoods of 

people and the contribution (or potential contribution) of aquaculture to 

livelihoods through the existing farming practice 

● Recognize and respect the innovative potentials of farmers (Farmers are also 

scientists). Give them confidence and opportunity and do not underestimate 

the potential of farmers for innovation. 

● Provide farmers with the science behind the technologies and not just 

technologies. Provision of principles encourages people to adapt/innovate 

technologies appropriate to their own farming system. 

● Do not promote risky systems. Avoid heavy external input activities and help 

farmers to use locally available resources. 

● Organize farmers. Help farmers to organize themselves and address problems 

on a community basis by establishing access to information: markets, 

formation of self-help groups, etc.

The scaling up process used by CARE 

can be grouped under two 

categories: horizontal scaling up 

(people to people) and vertical 

scaling up (institutions to people). 

Horizontal scaling up 

CARE has been involved in scaling up 

the aquaculture activities by directly 

working with farmers. About 800 staff 

members are involved in scaling up 

aquaculture activities throughout the 

country. However, these staff members 

are not exclusive to aquaculture, but 

are integrated agriculture 

development professionals who treat aquaculture as part of a larger farming system. 

Vertical scaling up 

To reach more people and ensure sustainability of the activity, partnerships with 

different institutions like non-government organizations (NGOs), community-based 

organizations (CBOs), youth/cultural organizations in the villages and government 

departments involved with agriculture/fisheries are developed. 

Extension agents 

CARE experience has demonstrated that farmer-centered and processoriented 

approaches require staff with strong facilitation skills and a 

passion for participatory approaches. Staff with diverse backgrounds are 

recruited and trained to work as extension agents. Often experienced 

farmers can also play this role. There is a small group of technical staff for 

aquaculture, agriculture, forestry, environment, economics, sociology, 

monitoring and evaluation. These specialists help the extension agents in 

understanding the principles of technologies and issues. Extension agents 

with holistic approaches address the issues and provide support to farmers 

in solving the problems. This differs from the predominant extension 

approach wherein technical departments from each area like agriculture, 

horticulture, fisheries, provide support independently. The new approach is 

useful in reducing cost and meeting the needs of farmers. 

Research/information partnership: Partnerships with universities, national and 

international research institutions, agencies involved in development work within and 

outside the country are developed. These partnerships have been mutually 

beneficial and will become productive when there are well-defined frameworks. The 

partners serve as good sources of information as well as good centers to disseminate

information so that it will reach the right people involved in such activities. 

Horizontal scaling (people to people) 

This process’ major focus is the transfer of information from people to people. For 

effective upscaling, good institutional structure and people with clear vision are 

essential. 

Human resource development 

Importance is attached to human resources since the extension system revolves around the staff’s 

capacity to enhance the knowledge of farmers and their interest in learning from each other. To bring 

the fundamental change in the attitude of staff from "I know everything" to "I learn with you" requires 

considerable amount of time and energy. 

Foundation training for the staff usually covers one full crop cycle (like rice-fish, about 120 days). It 

focuses on improving facilitation skills; building staff skills in using the experiential learning cycle; 

self discovery; enhancing staff knowledge on the livelihoods of people, social and gender issues; 

discovering the principles of technologies; gaining confidence in the use of extension strategies. 

Staff development is considered a continuous process and resources are allotted to build staff 

capacity. Self-evaluation at the end of each crop cycle is undertaken (What was achieved? What could 

not be achieved?). An enabling environment must be created where staff members feel free to express 

themselves without fear and where they are encouraged to learn from mistakes. Staff development and 

management are core elements of scaling up activities. 

Working with farmers 

Working with farmers generally consists of the group approach following a farmer field school 

strategy, wherein farmers meet at regularly to learn together, through action-oriented educational 

approaches. CARE projects treat aquaculture as a component of the farming system. In a village 

where groups of 25-30 farmers are formed, there could be only four to five farmers who might be 

interested in aquaculture. In such occasions, small sub-groups are formed. The general principles in 

farmer field school approaches are as follow: 

● Learning contract. Each group is encouraged to establish a learning contract in which the 

commitment of all parties is included. 

● Field is the classroom. Farmers identify the problems and areas where issues have to be 

addressed. Plans are developed by the farmers to meet their own needs. 

● Curriculum focuses on science, not just technology. Based on the identified needs of the 

farmers, curriculum is developed to increase their knowledge. Sometimes, progressive farmers 

are used to develop a curriculum appropriate to the village. Learning sessions could vary in

number depending on the importance farmers attach to the issue. 

● Meet on set days and set time. Generally, each group meets at least once in a fortnight and 

undertakes observations collectively. In addition to these fixed meetings, extension staff also 

provides follow-up support. 

● Make time for analysis and synthesis. At the end of the session, results are analyzed by the 

farmers and shared with others. Farmers’ science congress is also becoming popular. In these 

meetings, farmers share and analyze results with other farmers. 

● Working duration. The cycle of direct interaction with the farmers generally covers 12-24 

months. This provides opportunity to cover 2-3 cycles of rice-fish and at least one full cycle of 

annual crops like pond fish. 

Extension agents 

Consider these processes in scaling up aquaculture 

1. Farmer field school extension strategy – group learning opportunity 

for adults organized in fields. 

2. Family approach – involve both male and female from each 

community. 

3. Community approach – help bring more areas under aquaculture 

like in community fish culture. Also, it is a tool to create community 

harmony. 

4. Farmer leaders – choose farmer leaders acceptable to community 

and help them establish access to information on a sustainable basis. 

5. Aquaculture education to children – incorporate lessons in 

aquaculture in schools and help children to learn about aquaculture 

through practice. Children are powerful vehicles for information 

dissemination. 

6. Farmer participatory research – encourage farmers to conduct 

research using their own resources to develop technologies 

appropriate to each area. Help farmers to analyze and disseminate 

the information . 

7. Participatory monitoring, evaluation and planning – use tools and 

development indicators acceptable to farmers to measure progress. 

8. Opportunities for discussion where farmers learn from each other. 

9. Mass communication approaches – newsletters, posters, radio, TV 

programs, billboards in local languages are good ways to create 

awareness. But to ensure action, support is required and this should be 

planned. 

10. Cross visits – a most effective strategy: farmers can communicate in 

their own language. 

11. Farmers science meet – apart from field days (which give an 

opportunity for the farmers to see): organize village fora to discuss the 

results obtained.

Increasing secondary adoption rates 

Farmers are encouraged to teach other farmers. Although successful activities are adopted easily by 

other farmers in the village, conscious efforts are necessary to increase adoption rates. 

Consider these processes in scaling up aquaculture 

Farmers are viewed as development partners and not beneficiaries. 

Staff are viewed as knowledge and learning catalysts and not 

information givers. 

Projects are viewed as educational programs not a technical 

intervention. 

Focus on learning skills and mechanisms for learning and not on giving 

information. 

Vertical scaling up 

Partnership with NGOs 

To reach larger areas and more people, partnerships with other NGOs and CBOs, 

youth organizations, etc., are useful. 

While fostering partnership, remember: 

1. Partners should have shared vision and values. 

2. Adequate time is necessary in the selection of partner NGOs. 

3. Capacity building of NGOs/CBOs should be a priority. Long term strategies 

and building collegiate types of relationship should receive priority. 

4. All transactions should be transparent. Adequate support should be provided 

to improve program and financial management of the organizations. 

5. Inclusion of local farmers in various trainings would be useful. 

6. Partnership should focus on long-term institutional linkages.

Why rice-fish has been spreading widely in CARE project areas 

The success of rice-fish has been attributed to the promotion of cultivation 

of both rice as well fish by the same extension agent. When these two 

components are promoted by two different extension agents, the result is 

poor. 

Rice-fish culture is generally sustained by the farmers. In areas, where the 

activity was not sustained, poor participation of women was a major 

factor. Involvement of both male and female farmers from the same family 

assures sustainability. 

Partnership with government agencies 

Working with the Department of Agricultural Extension/Department of Fisheries 

achieves wider coverage. As there are many differences in the working environment 

and approaches used, strengthening of these partnerships require an understanding 

of each other. Some of the challenges encountered are: bureaucratic systems, 

hierarchical attitudes, non-acceptance of NGOs as equal partners, poor pay 

structure in the public sector and lack of pro-poor policies. 

Partnership with research and development 

Partnership with the universities and research organizations has helped in addressing 

many issues and in stimulating research for farmers. Many of the findings of these 

research institutes are transferred to farmers for further testing and adaptation. On 

the other hand, practical problems encountered by the farmers are fed back to 

researchers. 

Conclusion 

Consider these criteria in scaling-up aquaculture 

1. Aquaculture should be a felt need of farmers 

2. Inputs should be easily and locally available 

3. Activity should not add undue risks to farmers 

4. Socially and culturally acceptable 

5. Environmentally-sound 

6. Economic benefit derived should be high 

7. Market opportunity 

8. Technology should be gender sensitive 

9. Favorable policy environments 

10. Appropriate institutional structures

Aquaculture can make a significant impact on people. To achieve such an impact, 

changes are necessary in the extension processes. Following are the major lessons 

learned from the scaling up processes. 

1. Scaling up is sustainable when education processes are adopted and 

participatory approaches are employed at all levels. 

2. Scaling up should not be mistaken for replication. Every farmer should be 

encouraged to investigate and adapt the new information to suit his farming 

system. 

3. Scaling up can have maximum impact on people with good policy 

environment. Hence, partnerships with government agencies, that can influence 

policy changes, would be useful. 

4. Scaling up is faster and sustainable when holistic and integrated approaches 

are used. Treat aquaculture as a component of the farming system. 

5. Scaling up quality entirely depends on the staff and, hence, staff development 

should be given the highest priority. 

6. Scaling up requires an assurance of male and female participation. 

7. Scaling up success and sustainability also largely depend on community 

participation in the activity and, hence, the use of community approaches as 

appropriate. 

8. Scaling up can be enhanced and sustained by using participatory planning, 

monitoring and evaluation. 

Prepared by: 

M. C. Nandessha and A. K. M. Reshad Alam

Scaling Up the Impact of Aquaculture: 

AquaOutreach at Asian Institute of Technology 

Horizontal scaling up through distance extension 

The Asian Institute of Technology AquaOutreach Program’s (AOP) approach to 

horizontal scaling up is based upon careful on-farm testing of technologies with 

representative farmers, i.e., trial and not demonstration. The approach, however, has 

been at individual farm level, rather than in a group, although several farm trials may 

have been conducted in a particular village. Technology is modified according to 

farmers’ needs and verified with a larger group of farmers before it is considered 

ready for dissemination. 

However, with a limited budget and a small staff, based in a regional university, the 

Program has not been able to operate as a separate development project, at least 

since the beginning of 1993 when it expanded its scope beyond Northeast Thailand. 

Partly by default, partly by choice, it has had to work through government 

institutions, which also had very few, if any, extension workers. 

In its initial work in Northeast Thailand, therefore, AOP analyzed the extension options 

available and concluded that for wider dissemination of information, a distance 

extension approach had to be adopted, with heavy emphasis on the use of mass 

media. It was important, however, that the medium of dissemination, just like the 

technology (the message of extension), was carefully designed and tested with 

farmers. For example, the AOP: 

● Tested various forms of mass media in its experimental extension trials,

including television and radio, as well as posters and leaflets. 

● Examined which radio channels farmers listened to and when they were most 

likely to watch TV, to create awareness of the new technical options available. 

● Tested draft posters and leaflets both with trial farmers and those who have 

not been exposed to the project to ensure understanding of the language 

and pictures used. 

● Used the feedback received to make several drafts of the materials before 

they were declared ready for publication. 

● Disseminated the printed materials through non-specialist channels like local 

schools, health centers and agricultural extension offices (AOP, 1994; Demaine 

et al, 1994; Demaine and Turongruang, 1996; Turongruang and Demaine, 

1997). 

The AOP tested this approach in several contexts where it did not have any 

direct contact with farmers. Results appeared to be remarkably consistent. 

Follow-up by the staff showed as many as 40% of farmers who received the 

leaflets followed at least one of the technical recommendations, although 

many followed the principle, rather than the exact practice. Around 70% 

were still following the recommendations several years later. Similar results 

were achieved where extension materials were handed out during training. 

Of course, such an approach could not specifically target poor people. The 

assumption is that if a technology has been tested successfully by the poor, 

having been applied for a number of years, then it should also be accessible 

to other poor people with the same level of resources. Evaluation, which 

looked into indicators of socio-economic status, suggested that those 

adopting aquaculture through this system were no better off than the 

regional average. Given the amount of materials distributed, AOP estimates 

that use of carefully developed and tested extension materials, which were 

based on equally carefully tested technical recommendations, has spread 

to well over 10,000 households in the region. 

Vertical scaling-up: Capacity building and provincial networks 

A capacity building approach has been at the heart of the AOP. The program has 

worked through national government research and development institutions, 

primarily at the provincial level, to introduce new approaches to small-scale 

aquaculture research and development and new management systems. 

● In Thailand, for example, the AOP acted as the catalyst to draw together the 

staffs of research stations and provincial fisheries officers into a single system 

focused on rural aquaculture. Provincial officers do research through on-farm 

trials while research stations collect data on the social and economic 

conditions of farmers to establish the focus of their activities.

AIT’s Outreach Program’s approach has evolved over time through the 

following phases: 

1. Campus-based scientists working individually 

2. Teams of natural and social scientists doing field research and 

working on development problems 

3. Teams of natural and social scientists assisting national institutions in 

capacity-bulding for institutional development 

4. National governments adopt policy changes based on results of 

field-based research and improved curricula. 

By improving and adapting what already exists, the AOP enables systems to be transferred within and 

between provinces. This is like translating the farmer-to-farmer extension mode described above into 

aquaculture support services. 

● In the Lao People’s Democratic Republic, systems were developed in Savannakhet province, 

which then became the model for Khammouan and Champassak in the north and south. Now a 

network of six provinces in south central and southern Laos works together in planning, 

implementing and reviewing activities. A training unit in Savannakhet has developed skills 

which can serve all six provinces. 

● A slightly different mode has developed in southern Vietnam, where AOP's initial phase of 

operations concentrated on building capacity at the Faculty of Fisheries in the University of 

Agriculture and Forestry (UAF) in Ho Chi Minh City. The UAF group slowly expanded 

project activities to several provinces in southeast Vietnam, which now constitute a network 

that develops and sets the annual work program, with technical backstopping from the 

university. With limited resources, the provinces are now seeking ways to expand the initial 

experience to wider groups of farmers. 

The next step is the adoption of the approach as national policy. In the case of the AIT Aqua Outreach 

Program, the evidence that the technical recommendations can have a positive impact on the 

livelihood of small farmers and that the approach is appropriate given the resources available to local 

administrations led to a growing acceptance by policy makers that the model can be adopted as 

national policy. (Demaine and Edwards, 1998) 

● In the Lao PDR, the Regional Development Committee has been designated as the 

organization responsible for developing a strategy for the livestock and fisheries sector in 

southern Laos. 

● In Cambodia, evidence offered by AOP and similar projects have persuaded the Department of 

Fisheries to establish a separate Aquaculture Office to consolidate efforts in the sector. 

● In Vietnam, the work of Aqua Outreach and the United Nations Development Program 

(UNDP) has led to the formulation of a strategy for Sustainable Aquaculture for Poverty 

Alleviation in the Ministry of Fisheries.

Conclusion 

The acceptance of this approach as policy has been based on a clear 

demonstration of impact and relevance through pilot projects, not through 

advocacy of such approaches at national level. 

The two dimensions of scaling-up – horizontal and vertical – involve the testing of 

possible technologies with the participation of farmers to make sure the innovations 

are acceptable to clients before they are disseminated through farmer-to-farmer 

interaction. 

In AOP, the trial has been on an 

individual farm basis. Extension 

materials were later produced using 

the results from the trial and with 

farmer participation. Like the CARE 

project described in another paper, 

the extension effort involves nonspecialists 

in the on-farm research 

dissemination process. Both projects 

recognize the need to develop 

networks for vertical spread. In AOP’s 

case, the project works within the 

government system, emphasizing 

capacity building at provincial and district levels to reach small-scale farmers on a 

country or region-wide basis. 

References 

Aquaculture Outreach Program. 1994. The AIT Outreach Extension Experiment 

1991-92. Working Paper No.14 (revised edition), AIT, Udorn Thani, Thailand. 

Demaine, H., D. Turongruang, P. Phromthong and P. Mingkano. 1994. Monitoring 

Survey of Extension Experiment Farmers 1993. Working Paper New Series T-2, AIT 

Aquaculture Outreach Programme, Udorn Thani, Thailand. 

Demaine, H. and P. Edwards. 1998. Aqua Outreach: Towards a Model for SERD? in 

Salokhe, V.M. ad C. Polprasert (eds) Proceedings of the 5th SERD Seminar on 

Relevance of Outreach in Technology Transfer, November 11, 1997. AIT, Bangkok, 

1-16 

Demaine, H. and D. Turongruang. 1996. Distance Extension for Rural Aquaculture 

in Northeast Thailand. Paper presented at the World Aquaculture Society, 

Bangkok.

Edwards, P. and H Demaine. 1998. Completing the Problem-solving Cycle in 

Aquaculture: The AIT Aqua Outreach. Aquaculture Asia 3(3): 10-17 

Regional Development Committee (RDC). 2000a. The Nursing Network. Poster 

submitted to the DFID Aquatic Resources Management Programme e-Mail 

conference on Aquatic Resources Management for Sustainable Livelihoods of 

Poor People. 

Regional Development Committee (RDC). 2000a. The Book System. Poster 

submitted to the DFID Aquatic Resources Management Programme E-Mail 

conference on Aquatic Resources Management for Sustainable Livelihoods of 

Poor People. 

Turongruang, D. and H. Demaine. 1997. Participatory Development of 

Aquaculture Extension Materials and Their Effectiveness in Transfer of Technology: 

the Case of the AIT Aqua Outreach Programme, Northeast Thailand, Paper 

presented at the Asian Fisheries Society Forum, Special Symposium on Rural 

Aquaculture, Chiangmai, Thailand, November 13, 1997. 

Prepared by: 

Harvey Demaine

Participatory Approach to Extension and Training 

in Aquaculture 

The fundamental objective of extension is development which is not limited to 

physical and economic 

aspects alone. Extension emphasizes development of peoples’ overall capacity to 

help themselves. One such successful extension approach is known as the trickle 

down system (TDS) of aquaculture. 

Genesis and concept 

Experience gained from extension services of the food farming sector indicated that, 

in addition to a dedicated and efficient extension services network, an appropriate 

extension approach is also needed to provide a definite direction to the program 

operation and to amplify its impact. 

The approach was designed based on two core principles: 

1. Get closer to the client groups and get a firsthand insight of their socio-economic 

settings, farming practices, level of knowledge and skills, needs, opportunities and 

constraints. 

2. Foster participation of the client groups in planning and implementation of the

agreed program. 

Trickle down system (TDS) 

This approach was developed and successfully demonstrated on a limited 

scale in Bangladesh through the FAO/UNDP project "Institutional 

Strengthening in the Fisheries Sector" in 1990-1993. The approach was 

piloted in 52 (out of 64) districts of the country in 1994-1996 through the 

FAO project "Strengthening Pond Fish Culture Extension". The pilot project 

helped to fine tune the approach. Subsequently TDS was applied on a 

national scale by the Department of Fisheries (DoF) in Bangladesh, 

Northern Vietnam and some parts of Sri Lanka. 

The TDS approach is a participatory, farmer-to-farmer extension approach, which 

involves bottom-up participatory planning and implementation of the extension 

program. This results in the "trickling down" of knowledge and skills of improved 

technology from result demonstration farmers (RDFs) to fellow fish farmers (FFs). 

Clientele 

Families with their own pond or any other type of aquaculture facility or have access 

to such a resource. 

Functional design 

● Once a site is identified, village communities and opinion leaders/social 

workers, including progressive farmers, are approached and a local level 

assembly is organized in the form of a field level training session. This method 

was subsequently replaced by a combination of rapid rural appraisal (RRA) 

and field training. Finally it was found that the participatory assessment, 

planning and action (PAPA) approach at individual and community levels was 

more effective. 

● By using the PAPA, a broad participatory assessment is made of the size and 

type of aquaculture resources, local availability of essential inputs, range of 

farming practices, local farming skills, ability to mobilize the extraneous inputs, 

constraints, etc. With this information and giving due consideration to the 

existing socio-economic environment, a plan is prepared for development 

through aquaculture. Measures are discussed to improve existing practices. In 

addition, the appropriateness of certain alternative technology packages is 

assessed. 

● Before a planning workshop or training is organized, it is made clear that no 

form of monetary incentive can be expected.

● Once the plan is prepared, one or two RDFs are selected by the group to 

undertake an improved/appropriate culture technology trial. The rest of the 

participants are designated as fellow farmers (FFs). They watch and wait for 

the outcome of the trial. Again, before the RDFs are chosen, it is made clear 

that, except for on-site training and technical advice, no material or financial 

support will be given to those selected. This is meant to avert future 

complications and ensure sustainability of the activity. 

● Adequate 

extension support is 

given to the RDFs 

through repeated 

short-term 

instructional 

training and 

periodic home/site 

visits to 

demonstrate the 

improved 

aquaculture 

technologies in 

their ponds. RDFs 

get on-site 

practical training 

using method 

demonstrations at least two to three times in the course of a complete 

cropping cycle. Home/site visits are made once or twice a month depending 

on the specific need and nature of the culture practice. Participation of both 

men and women family members is ensured. 

● Emphasis is also given to developing leadership qualities as well as 

technical and extension skills. 

● Once the crop attains a presentable stage, RDFs are encouraged and assisted 

in organizing practical trainings for the FFs by demonstrating the various steps 

of culture technology. The role of the RDFs is constantly highlighted and 

appreciated, enhancing his/her status in the community. This was a valuable 

incentive for them. RDFs were,thus, groomed as voluntary extension workers of 

the Department of Fisheries (DoF). This inspired the RDFs to take more interest in 

propagating the aquaculture technology in their area. 

● In subsequent cropping cycles, some FFs came forward to take up the culture 

practice and act as demonstration farmers, thereby becoming RDFs, with their 

own FFs. This process continues in the locality with little support from the 

extension services system. 

● Extension training tools and materials were specially designed to make the 

training more participatory, effective and useful. 

● Certain incentives were given to RDFs in the form of medals, public 

felicitations, etc., in recognition of their services to the farming community. This 

encourages them to take up extension work as a social responsibility.

● The process 

emphasizes the 

facilitation of the 

learning process. 

Instead of using the 

conventional 

technology transfer 

method, extension 

volunteers are 

encouraged to "walk 

the learning path," 

think and try new 

ideas for improving 

their farming practices 

and facilitating 

collective 

development actions. 

When farmers and 

communities are 

involved from the very beginning, they become active partners in the 

implementation of programs. This approach prevents the entry of vested 

interest groups that would mislead and exploit the farmers. 

The approach helped inculcate an "extension" culture among the senior and fieldlevel 

staff of the DoF and institutionalized the department’s aquaculture extension 

services system. It is worth mentioning that unlike the agriculture sector, where the 

primary activity is extension, the fisheries sector has multi-faceted responsibilities 

ranging from management of fisheries and aquaculture resources under 

state/public ownership such as rivers, lakes, reservoirs, flood plains, etc.; enforcement 

of fisheries acts and regulations; and providing extension services to farmers and 

fishers. Most of these resources are in remote places, not easily accessibille to the 

public transport system. With RDFs serving as local extension volunteers, the pressure 

on government extension personnel is reduced. This approach, based on "farmer to 

farmer" principles, was used for the first time in Bangladesh and was received 

positively by government and non-government organizations (NGOs). 

Local variation in 

Vietnam 

The approach takes advantage of the strength of existing local level community

institutions by involving them in participatory extension activities. Various 

organizations such as Women’s Union, Youth Union, Farmers’ Association, and 

People’s Committee are strong and active even at the local level (commune). A 

commune action group (CAG) is organized to develop aquaculture in the 

community. It is composed of one member from each of the existing local 

organizations, including one local aquaculture farmer. CAG members are trained in 

participatory resource and constraints assessment, planning and action for individual 

and cooperative level initiatives to develop aquaculture. After training, CAG 

members take the lead in organizing a commune level participatory planning 

exercise and select Demonstration Farmers. This approach is being used in the 

"Aquaculture Development in Northern Uplands" project in Vietnam of the Food and 

Agriculture Organization and United Nations Development Program (FAO/UNDP).

The impact of this extension approach was demonstrated by the FAO-TCP 

project prompting the Government of Bangladesh to launch a five-year 

nationwide project exclusively through national funding. An inter-ministerial 

evaluation was conducted during the last phase of the project. The group was 

highly satisfied with the program and its impact on the development of pond 

aquaculture in the country. Based on the body’s recommendations, another fiveyear 

phase is now being implemented and will be integrated into the 

Department of Fisheries as a regular activity. 

Local level variation in Sri Lanka 

In Sri Lanka where seasonal tanks hold vast potential for the development of inland 

aquaculture, TDS is largely a group-to-group approach. Local communities involved 

with any specific seasonal tanks are organized for planning and development of 

aquaculture through collective actions. Other groups associated with nearby 

seasonal tanks are invited to observe the development process and plan their 

development program in the subsequent season. 

References 

FAO. 1996. Strengthening Rural Pond Fish Culture Extension Services 

(TCP/BGD/4451). Project Terminal Report. 16 p. 

FAO. 1998. Freshwater Fish Culture Extension. FAO/UNDP Project VIE/93/001. 

Project Terminal Report. 22p. 

Karim, Mahmadul. 1997. A Review of Aquaculture Extension Services in 

Bangladesh. FAO RAP Publication 1997/35. Bangkok, Thailand. 54 p. 

Kumar, Dilip. 1999. Trickle Down System (TDS) of Aquaculture Extension for Rural 

Development. FAO RAP Publication 1999/23. Bangkok, Thailand. 54 p. 

Prepared by: 

A. K. M. Reshad Alam and Kevin Kamp

A "Farmer Field School" for Aquaculture 

Many extension strategies are limited to demonstration of technologies or providing 

advice via workshops and individual farm visits. Often the fundamental issue is a 

technology that has been packaged for farmers. Farmers are required to remember 

and replicate these systems on their farms. This may be one of the primary reasons 

why aquaculture successes have spread more slowly than expected. 

It is about time that an alternative model of extension is considered, one which 

encourages a holistic understanding of aquatic ecosystems, and embraces farmers 

as partners in technology development. The alternative approach should address 

livelihoods and empower farmers with greater planning, monitoring and decisionmaking 

abilities. This can be achieved through a "farmer field school" approach to 

aquaculture. 

Production technologies: refocusing on the basics 

Many aquaculture technologies in Bangladesh are promoted in a conventional 

manner, focusing on how to increase yields. The approaches do not consider the 

current level of knowledge, capabilities and opportunities of small-scale farmers. Too 

often, the technology focuses specifically on systems that require high levels of 

external and internal inputs (piscicides, supplementary feeds, inorganic fertilizers, 

etc.) applied in a very specific manner.

Extensionists will do well to contextualize the content of their demonstrations 

and the methodology they use to ensure their relevance to the situation of 

farmers they work with. 

By listening and learning from the farmers, extensionists can recommend 

those techniques and technologies most suited to the farmers’ situations. 

Rather than introducing a predetermined technology and its 

accompanying practices, providing farmers an array of practices to choose 

from generally results in greater adoption rates. Farmers can select and 

adapt those practices that suit their own unique needs. They are actually 

involved in the development not only of the technology system, but of the 

practices that define it. 

Alternative approaches help the farmers gain a fundamental understanding of 

aquatic ecology. They can then work with the extension professionals to design, 

implement and evaluate the impact of potential new practices and to develop 

appropriate, farmer-specific technologies. Learning approaches should be 

experiential, discovery-based and need-driven as well as tailored to the goal of 

transforming farmers into experts of their own aquatic systems. The first step in this 

transformation is to help farmers understand the aquatic system. 

Farmers as experts 

Farmers can be experts of their own ponds. What would it take to make them 

experts? 

1. Extensionists must believe that farmers can be experts. Without this 

fundamental belief in the capabilities of farmers, it is unlikely that a program to 

enhance their abilities will succeed. 

2. Rethink technologies and practices. Focus learning efforts on understanding 

the basics of aquatic ecosystems. 

3. Make the invisible visible. Develop methods that will allow farmers to 

actually see, feel and hear what is going on under the surface of the water. 

4. Provide opportunities for farmers to put concepts together. Develop possible 

practices and technologies and test them with the farmers as a group . 

Encourage farmers to set the research agenda. This may mean ensuring a 

number of small pits, ditches or ponds are available. Planning, implementing, 

monitoring and evaluating together can be a powerful experience for farmers 

and can provide them with valuable skills. Group work also acts as an 

information, education and communication tool. More people will be reached 

by this method and will want to take part in the learning process.

5. Develop strong management tools that farmers know how to use. Farmers 

need tools to quickly and easily monitor the "health" of the pond, the results of 

which will encourage and support management decisions. 

6. Enhance farmers’ expertise to ensure the sustainability of aquaculture and 

institute a process by which farmers take the lead in innovation and 

development of new technologies. The role of the extension worker will be to 

support the farmers’ learning opportunities on a regular basis. 

Extensionists have to learn how to 

communicate more effectively to 

enable farmers to easily grasp the 

alternative practices (and hence learn 

what is best for them). 

By demonstrating and asking the 

farmers to carry out simple practical 

"experiments" and by giving concrete 

visible examples, farmers can quickly 

grasp the philosophy behind a new 

technology/technique being 

introduced. 

By listening to and learning from the farmers, the introduction of new 

technologies would be much simpler and enjoyable. Both extensionists and 

farmers will easily notice that the new technologies do result in higher levels 

of yield and profit and actually match the goals and specific resources of 

individual farmers. 

Discovery-based, experiential learning 

1. Farmers learn the effect of fertilizers on phytoplankton 

Farmers easily discover this when asked to do the following. 

● Put some water in a number of plastic jars. 

● Add different types of fertilizers and manure to each plastic jar. 

● Experiment with different amounts of fertilizer and manure in each jar. 

● No fertilizer or manure should be put in some of the jars, which will serve as

control jars. 

● Expose the mixtures to sunlight for four to six days. By carrying out this simple 

experiment on his own, a farmer will learn about the impact of organic and 

inorganic fertilizers on phytoplankton growth. He may even go so far as to test 

the nutrient levels in his pond’s water by adding various doses of different 

nutrients to see which has the most impact on phytoplankton growth. He can 

document for himself if indeed nitrogen is not limiting and phosphorus is. 

2. But so what if he can produce more 

phytoplankton? 

The farmer now needs to understand 

how phytoplankton is consumed by 

the fish or how it increases the 

production of zooplankton (next 

organisms up in the fish food chain). To 

test this: Ask the farmer to put 

zooplankton in plastic jars with the fish 

and to observe closely to be sure that 

the fish are actually eating the 

organisms. 

3. Farmers learn the benefits/effect of 

using lime over water 

Apply small amounts of diluted lime in plastic bottles containing different types of 

water generally found in the village (e.g., turbid water, polluted water, water with a 

high organic level, etc.) After applying the lime into the bottles, the farmers should 

be able observe how, in 10 minutes, different types of water become clear. This 

exercise should strengthen their belief that lime can purify water. 

4. Farmers become empowered to make the best decision on managing predators 

and small fish 

Help farmers learn about the range of predatory fishes that exist in ponds by 

sampling small pits in rice fields. Farmers will be able to learn about the diversity of 

species found in small water bodies. They will find not only fish species, but various 

snakes, insects, and other benthos organisms in such dynamic water bodies. By 

draining a small pit and removing the fish, they will understand the impact of drying 

such an aquatic ecosystem and how quickly it is reestablished with invertebrate and 

vertebrate organisms. By netting the pits before they are drained and dried, farmers 

will also learn the efficiency of netting to remove predatory and small fishes, and 

how many times it had to be done. 

5. Farmers will only be able to decide on the best supplementary feed to use if they

are provided with pits and small ditches where they can experiment 

The recommended supplementary feed items in Bangladesh usually involve rice 

bran and oil cake. Both can be expensive and might not actually be needed. How 

does a farmer decide? 

The use of small ditches where groups of farmers can plan, implement, monitor and 

evaluate their own experiments is important, not only for learning specific concepts, 

but for putting together practices based on these concepts, trying them out in the 

real world, and continuing the learning process long after the extensionist has 

moved to another district. Design and observation skills are critical for this process. 

Remember! 

It is important to use methods and examples relevant to the farmers’ 

situation that they can relate to. This will increase their self-confidence to 

make observations and decisions based on the observations. Their 

observations and experiences will enable them to calculate doses and to 

learn about the appropriate types/levels of fertilizers to use in ponds. 

Farmers, who want to evaluate the 

effectiveness of rice bran and oilcake 

compared to pond fertilization food 

production strategies, would need a place to 

do it. They can discover the real answer for 

themselves depending on the quality of the 

pond. 

Conclusion 

A "Farmer Field School" approach is an 

empowering process to enhance the 

decision-making capabilities of farmers. 

Through the process, farmers can relate to 

the technology that the extension worker is 

trying to introduce. This approach requires 

that farmers be recognized as experts in their 

own ponds. 

Prepared by: 

A. K. M. Reshad Alam and Kevin Kamp

Aquaculture Development and Information 

Processes 

The challenge in aquacultural development is to assure and be able to verify that 

target populations have actually benefited from such efforts. Even successful 

programs have had to face these challenges. Enough poor results exist to justify a 

brief examination of the previous and current models and processes for aquaculture 

development. 

Causes of failure

There are plenty of examples of the 

failure of aquaculture development 

efforts to live up to expectations in 

spite of the good intentions of those 

who designed and implemented the 

projects. In some cases failure 

resulted from inappropriate 

technology (e.g., trout facilities in the 

tropics) or lack of appreciation of 

the complexity of farming systems in 

which aquaculture is to be 

introduced (e.g., assuming labor or 

animal wastes do not have 

competing opportunities). More 

often, however, failures are linked to 

external forces (e.g., breakdown in 

law and order) or the inability to cut 

through ineffective and underfunded 

governmental systems (e.g., 

failure to release budget support on 

time). 

Another problem is failure to build a 

comprehensive system needed for 

aquacultural development. The 

following diagram is a conceptual 

model of a holistic system that 

highlights the interconnectivity of 

different elements and functions. 

Any specific development effort 

might address part of the model but 

ultimately, all the supporting 

functions must be addressed for an 

aquaculture industry to be sustainable. An extension system can be temporarily 

enhanced but without an effective training mechanism to bring new people into the 

system and a research source to infuse new and proven technology, it will 

eventually collapse. Similarly, research needs new scientists from training programs 

and, in turn, should provide updated information to keep education relevant. 

Research-based aquaculture technology is vital to guide extension, education and 

development efforts. It is also essential to have an administration system that 

provides an environment that allows the different functions to operate, including the 

legal framework and public infrastructure. 

The model should make it clear that the support systems have to be sustainable. All 

too often a program that is introduced, often with foreign assistance, runs for a few 

years then fades at the end of the project. Program planners are generally aware of

the problem but political urgency and unrealistic expectations about the pace of 

development and institutional capabilities undermine the sustainability of support 

functions. 

Another problem is where and how support assistance is spent. Salaries, allowances, 

and overhead charges for specialists from the more developed countries can eat 

up a good portion of foreign development support. The program processes imposed 

by donor agencies can also be formidable and costly. Off-shore training of local 

scholars can be very expensive, time consuming, and may contribute more to the 

brain drain than to home country development. Many host country governments 

are notorious for their cumbersome bureaucracies (a feature also of some donor 

organizations) and sometimes outright graft. The net result is that little of the support 

actually trickles down to the truly needy. 

Paradigm shifts 

Past efforts to develop small-scale aquaculture have generally focused on helping 

rural poor and landless people, with particular emphasis on production and nutrition. 

Although these are important considerations, development planners are now 

thinking more in terms of profits and enhanced business success. An aquaculture 

product may be too valuable for a farmer to eat, but the income from its sale may 

enable the farmer to purchase other items such as health services, education for 

children or less expensive alternative food items, and to enhance their livelihood 

and help them overcome poverty. 

Information 

delivery

The question really is what does it take for a resourcelimited 

person to take advantage of the inherent 

opportunities of small scale aquaculture and how can 

the information be delivered efficiently? This assumes 

that small-scale aquaculture is economically viable in 

that particular setting, that soil, water and climatic 

conditions are not limiting, the technology is within the 

grasp of the adopter, there are markets, credit, seed 

stock, feeds or fertilizers, etc. All these factors, along 

with social considerations like water use rights, 

poaching risks, labor demands and so forth, should be 

considered before pushing for aquaculture 

development. 

One problem in development work is defining who 

should convey new information to farmers. In America, 

the land-grant university system has this responsibility 

and most countries, to some extent, charge their 

agricultural universities with some rural extension work. 

In the less developed world, typically this responsibility 

is given to some ministry or ministries like the Ministry of 

Agriculture. The agencies are often under-funded and 

ineffective in actually getting out and among the rural 

constituency. Official development assistance is often 

restricted to government channels. This is where 

external money goes (and sometimes siphoned off). A 

thriving NGO system has developed in some countries 

to help facilitate rural development through outreach 

and credit activities, particularly where public 

programs have left a void. 

A participatory approach, now considered essential, suggests asking the potential 

adapters how they would like to learn about and assess the opportunities for them in 

small-scale aquaculture. Establishing a continuing presence and an effective 

feedback mechanism can also lead to building information transfer processes. 

Working with groups such as a village women's organization may help facilitate the 

processes. 

The classical "extension method" suggests that the first step is to create an awareness 

that such possibilities exist. Traditional approaches include mass meetings, 

information leaflets, media programs, on-farm demonstrations and gatherings, etc. 

Working with groups may be the only approach that is practical and efficient .

There is a whole discipline dealing with extension education and lessons 

learned from that discipline should be understood and incorporated into 

rural development planning. 

It is one thing to work with collegeeducated 

farmers and another to 

work with landless peasants. In many 

places, the latter have low literacy 

rates, little formal education and 

limited exposure to mass media. The 

resources they bring to the tasks of 

aquaculture are basically their hands 

and perhaps some traditional 

knowledge picked up from their rural 

upbringing. Obviously, strategies to 

create awareness have to be tailored to the prevailing conditions in the target area. 

The time honored approach of guiding an "opinion leader" type person, perhaps 

one selected by a community through a participatory process, to adopt a given 

practice and share his experience with neighbors is still regarded as a good method 

for creating an awareness in a community. Sign boards, portable loud speakers, 

radio and television programs and curriculum models for schools have also been 

employed. 

A recent study in Bangladesh (FEEP), for example, asked fish farmers where 

they got their best advice. The most credible source identified was 

government personnel but it turned out that actual contact with 

government agents was minimal because they were few and were being 

diverted to functions other than extension outreach. Another project in the 

same country involves small fry/fingerling dealers in the belief that virtually 

every fish farmer comes in contact with them as they procure fish stocking 

material. 

In more industrial societies the private sector may also get involved both through 

vertical integration and market development. Thus, a fish feed manufacturer may 

have his own pond production facilities and also guide other farmers to assure their 

success and to expand his market for the feed. 

Where many interests promote aquaculture, there might be some 

contradictions on recommendations about how the farming should be 

done. Unscrupulous and ill-informed promoters are all too common in the 

aquaculture world. Poor peasant farmers are generally ill-equipped to sort 

through conflicting claims and tend to take the conservative approach of 

not changing their practices when their tolerance for failure is very low.

Subtle cultural features may help or destroy the effectiveness of the information 

transfer process. In the design of one project, for example, the purchase of bicycles 

for extension agents was discouraged because the mode of transport lowered the 

agents’ social status and credibility in the rural communities. It was better to have 

the money for pubic transportation and to walk than to ride a bicycle in this 

particular setting. 

The type of person charged with extension responsibilities is also very 

important. Some personalities are just better at some tasks than others. 

Technical knowledge and experience are desirable but these must be 

coupled with personal characteristics suited to the tasks of information 

transfer. Local individuals historically have had the most success as "farm 

agents" assisting with the adoption of new farming practices. 

Although there is some appreciation of information transfer processes, they are often 

poorly implemented, partly because the resources just do not trickle down 

adequately to support farmer-level operations. Outreach efforts have to assess 

where resources are spent and to ensure that field people and their operational 

needs are given priority. 

Prepared by: 

John Grover

Rural Aquaculture Development and Mangrove 

Conservation Projects (Initiated by Fishers in 

Collaboration with Various Institutions in Sri 

Lanka) 

This is a story on the positive impact of a unique and successful partnership between 

local communities, NGO’s and government institutions that launched recently a 

major program for the development of the aquaculture industry in Sri Lanka. The 

uniqueness of the approach lies in its eco-friendly rural aquaculture development 

projects aimed at the rural poor. 

The present per capita consumption of fish in Sri Lanka is estimated at 18 kg per year 

as against a required average of 21 kg per year. Faced with communal disharmony 

in the North and East of the country, fish flows and transportation to the cities and 

other parts of the island have decreased. As many villagers do not have easy 

access to the high seas, the only fish available for the rural poor is, decidedly, 

freshwater fish. 

Linkages have been established among the following organizations in an effort to 

boost the local production of fish: the Small Fishers Federation (SFF), a nongovernment 

organization (NGO); the National Aquaculture Development Authority 

of Sri Lanka (NAQDA), a statutory body under the Ministry of Fisheries and Aquatic 

Resource Development (MFARD); and the Food and Agricultural Organization of the 

United Nations (FAO).

The SFF grew from a development network set up in 1984 called "Fisher Folk-Based 

NGOs". The federation, funded by NORAD (a Norwegian goverment agency), 

played a pivotal role in the national food production program in the country and 

achieved optimum results through a community-based participatory approach. It 

effectively expanded and grew, becoming a Federation, through active 

participation. It has launched many beneficial programs such as crab culture and 

mangrove conservation projects in the northwestern province of Sri Lanka. Thus, SFF 

is rich in experience that can be shared with grassroot level organizations worldwide. 

Reasons for success 

Honesty and good leadership qualities demonstrated by SFF members 

Wise use of credit funds 

Proper site selection 

Application of appropriate (farmer-friendly) training methodologies 

At present, the SFF, together with government institutions, actively seeks community 

participation and extends assistance in solving individual and communal issues in the 

field of fisheries through the development and conservation of aquatic resources in 

island waters, coastal wetlands, offshore areas and the lagoons. 

SFF’s success stems from the 

strong institutional links it has 

formed with government and 

semi government institutions. 

The first step in this strong 

partnership was MFARD’s 

waking up to the reality of the 

severely limited and rapidly 

declining fisheries resources. It 

decided to collaborate with 

SFF. MFARD, finding that the SFF 

had a wide fishing community 

network on the island, formally invited the Federation to participate in the national 

endeavor to improve aquaculture fisheries. This was indeed a giant step. Before 

1994, NGOs and communities working with government departments was unheard 

of in Sri Lanka . 

Another milestone was a comprehensive legislation, the amended Fisheries and 

Aquatic Resources Act of 1996, which contained measures for "protection of fish and 

other aquatic resources" and raised concerns about the "sustainable use of aquatic 

biodiversity" in the fishery sector.

However, the rural poor were not actively involved until 1999 when NAQDA was 

established. NAQDA invited NGOs and the private sector to participate in its 

aquaculture projects. Although NAQDA works with many NGOs, such as Seva Lanka 

(Service to Lanka), Sri Lanka-Canada Development Fund and SFF, it is their 

partnership with the latter that proved to be the most successful. 

Of the many functions of NAQDA, the following are important for rural poor 

communities with access to communal waterways: 

1. Promotion of the optimum utilization of aquatic resources through 

environmentally-friendly aquaculture programs. 

2. Conservation of biodiversity. 

3. Promotion and development of small, medium and large-scale private sector 

investment in aquaculture. 

By actively seeking and inviting NGOs and rural communities to take part in smallscale 

aquaculture projects, an immediate sense of ownership was fostered. Projects 

started with a transfer of skills and technologies. Training kits were provided to 

participants. Technical support was extended to this government/NGO partnership 

with the implementation of the FAO/TCP/SRL/6712(A) – Aquaculture Development 

Project. The Inland Aquaculture Consultant of this project assisted the rural 

development program by training trainers, providing on-the-spot technical advice, 

helping in the design of mini-hatchery projects, and promoting innovative strategies.

One of these strategies was the promotion of low-cost carp production in 

undrainable ponds enabling the rural poor to gain additional income by selling carp 

fingerlings. (For additional information on this project refer to the paper on Low-Cost 

Aquaculture in Undrainable Homestead Ponds). Small-scale aquaculture in 

mangroves is now being promoted by providing support to poor coastal 

communities to start small-scale coastal aquaculture technologies. 

The Small Fisheries Federation (SFF) recognized that 

mangrove reserves were strategically important for 

many species including various types of fish, aquatic 

birds, shrimp, crab, mollusks and worms. The 

destruction of mangroves had adversely affected 

the local resident fishermen in these areas, with their 

daily hauls of fish in the Pambala lagoon in the north 

east coast drastically dropping on an average from 

4 kg to 1½ per day in the past three years. Also, the 

proliferation of unauthorized shrimp farms in the area 

posed a major threat to indigenous fishery in the 

Puttalam district (It was said that one third of all 

shrimp ponds were located on former mangrove land resulting in the loss of 

about 600 hectares of mangrove forest). 

Responding to a request to form a working-alliance by actively networking, 

building links and seeking support, the Small Fishers Federation, Mangrove 

Conservation Center, Pambala, Chilaw formally affiliated with the Mangrove 

Action Project (MAP) based in Seattle, Washington. The center was 

designated as the MAP-South Asian Resource Center Facility in Sri Lanka. 

With assistance from the FAO and extensive pilot tests, NAQDA was able to effect 

the technology transfer of three successful small-scale aquaculture projects in 

mangrove ecosystems: 

● mud crab fattening in wooden cages with PVC netting and culture in ponds; 

● sea bass/grouper culture in cages; and 

● mollusk culture 

The future is looking very bright indeed for this unique collaboration. Right now there 

are only three NAQDA-owned fish breeding centers and demand is much higher 

than supply. The project cannot supply the requirements of the entire island. 

Aquaculture projects of the rural poor have a huge untapped potential market.

Prepared by: 

Christie Fernando and R. K. U. D. Pushpakumara 

The Mangrove Conservation Center 

SFF Staff and members of a nearby local 

fishing community collaborate in running this 

Center. Community members actively 

participate in mangrove reforestation projects 

and small-scale silvi-culture including crab and 

oyster culture. 

A graphic description of the Mangrove 

Conservation Center’s activities in the past two 

years (1998-1999) is displayed on a large board. 

It proudly announces the planting of 144,000 

mangrove saplings at the Pambala lagoon 

area. 

The Center has become an active 

educational/training facility and a meeting 

place where fisher groups and academics often 

gather. 

A total of 186 seminars and conferences 

have been conducted with the participation of 

9,000 school children, 860 government officials, 

900 fisherfolk leaders and 500 mangrove lovers. 

Cooperatives formed by widows manage 

small revolving bank loans. Local school children 

learn coastal ecology and acquire natural 

resource management skills. 

The center has mounted15 exhibitions 

depicting mangroves, with a total of 27,000 

students attending, together with some 

government officials and mangrove specialists. 

Some 2,500 fisherfolks participated at the 

exhibitions. 

Seven research projects have been carried out 

to date.

Use of Geographic Information Systems (GIS) for 

Planning and Management of Aquaculture 

Maps have been in existence for thousands of years. However, in their traditional 

form, they suffer from a number of problems. First, maps are static and therefore 

difficult and expensive to update. To cite an example, maps exist as single sheets. In 

most cases, an area of interest lies on the corner of four adjacent sheets. In addition, 

maps are often very complex and an expert may be required to extract a particular 

data. 

Geographic Information Systems (GIS) can be regarded as the high-tech 

equivalent of a map. GIS provide the facility to extract different sets of 

information from a map (vegetation, soils, lakes, roads, settlements, etc.) 

and to use these as required. This provides great flexibility, allowing a paper 

map to be quickly produced. 

Geographic Information Systems (GIS) portray the real world. A view of the world as 

represented on a paper map reveals that the surface consists of points, lines or 

polygons. Thus, cities are usually represented by points, roads by lines and lakes or 

fields by polygons. 

The difference between a paper map and a GIS map is that in the latter information

comes from a database (i.e., set of data stored in a given file) and it is shown only if 

the user wants to see it. The database stores information like where a point is 

located, how long a road is, and even how many square kilometers a lake occupies. 

Each piece of information on a GIS map sits on 

a layer, and the users turn the layers on or off 

according to their needs. One layer could be 

made up of all the roads in an area. Another 

could represent all the lakes in the same area, 

yet another could represent all the cities. More 

importantly, a GIS combines layers of 

information about a place for a better 

understanding of that area. Determining how 

the layers of information combine depends on 

the user’s needs. For example, to find areas 

with potential for fish farming, it would be 

necessary to combine data like water, soil, 

land use, markets, cities, roads and population 

density. 

In both vector and raster systems, a 

geographic coordinate system is used to 

represent space. Many coordinate systems 

have been defined, ranging from simple 

Cartesian X-Y grids to spatial representations 

that correspond to the real world as latitude/longitude pairings. 

GIS has the potential for an enormous range of applications (e.g., business, defense, 

education, engineering, government, health, food security, transportation, natural 

resources, fisheries and aquaculture). 

Analysis methods 

Basically, any GIS study consists of five phases.

Software 

GIS software provides the functions and tools needed to store, analyze, and display 

geographic information. It ranges from low-end software for simple map display to 

high-end software capable of handling sophisticated models, Internet mapping and 

3D visualization. 

Factors in selecting GIS software 

● Intended use of the chosen application 

● Software and maintenance cost 

● Software "learning curve" 

● Current technical expertise of agency personnel 

Software availability in Asia 

GIS have developed rapidly in recent years. This development has been paralleled 

by a massive increase in low-cost computing power. As a result, very comprehensive 

tools for handling GIS data are now available to a wide range of users. 

A large number of GIS software are available ranging from free easy-to-use software 

to highly sophisticated and expensive packages. Countrywise, GIS activities and 

major GIS software vendors in the Asia-Pacific region can be located at: 

http://www.gisdevelopment.net/regional/. Available on the Internet at present are 

some free and easy-to-use GIS software such as Arc/Explorer 

(http://www.esri.com/software/arcexplorer/), and Windisp4 

(http://www.fao.org/giews/english/windisp/windisp.htm). 

An important consideration is that if an expensive GIS software is chosen, its cost

declines substantially as the tools and techniques are used for additional projects 

and data are shared among different departments (e.g., fisheries, agriculture, 

forestry, etc.). 

Hardware 

Hardware selection must relate to personal preferences, software, functional 

requirements, capital available, number of users, and the degree of interaction with 

other computer systems. 

The hardware components of a GIS include units that are common to any general 

purpose. 

● Computer such as several disk drives for storing data and programs 

● Tape drives for back up copies of data 

● Color graphic display units 

● Other general purpose computer peripherals 

In addition, GIS have several specialized hardware components. These include: 

digitizer or scanner used to convert the geographical information from maps into 

digital form to be sent to the computer; a plotter, which prints out the maps and 

other graphic outputs of the system; and a visual color graphics workstation on 

which spatial data editing and display can be performed. 

Sources of data 

● Primary data gathered in the field, such as direct mapping and field sketching, 

photography, interviews, questionnaires and measurements. 

● Secondary data are primary data that have been converted into a more 

accessible form (e.g., database within an organization, the Internet, mapping 

data providers, government organizations). 

● Proxy data refer to information derived from another data source, with which 

relationships have been established. Examples include estimation of water 

temperature from air temperature or extraction of semi-quantitative texture 

from FAO soil distribution maps. 

● Satellite data are in digital form and provide a rich source of information in a 

form suitable for use in GIS. 

Cost effectiveness 

The access to free or low cost GIS data is rapidly expanding, mainly via the Internet. 

Hardware and software are also developing rapidly and are becoming more 

powerful and affordable.

Evaluating outputs 

The final step is to look at the results of the analysis and take action based on those 

results. 

Results can be displayed as a digital map, printed as a paper map, combined with 

tables or charts or displayed as such. 

Trained users 

Whether the use of GIS is for casual or professional purposes, some form of 

education or technical training is highly recommended. Good training will equip 

people to better understand the process of GIS to apply it properly. 

Four main methods of learning GIS 

Formal GIS degree or certificate programs 

Instructor-led training 

Internet learning 

Self-study 

Main benefits derived from the use of GIS 

Improved planning and management 

A GIS can link sets together by common data, such as locations, helping 

departments and agencies share information. By creating a shared database, one 

department can benefit from the work of another. That is, data can be collected 

once and used many times. 

Make better decisions 

A GIS is not just an automated decision-making system 

but a tool to query, analyze, and map data in support of 

the decision-making process. 

Making maps 

Making maps with GIS is much more flexible than traditional manual or automated

cartography approaches. A GIS creates maps from data pulled from database and 

existing paper maps can be translated into the GIS as well. 

Who uses GIS? 

GIS can be used to help reach a decision about the location of a new fish 

farm in a suitable environment (e.g., good climate and soils). The 

information can be presented clearly in the form of a map and 

accompanying report, allowing decision-makers to focus on the real issues 

rather than trying to understand the data. Moreover, because GIS 

products can be produced quickly, multiple scenarios can be evaluated 

efficiently and effectively. Managers can test the consequences of various 

actions before mistakes are made in the landscape itself. 

GIS can be used by Fisheries Departments, applied research institutes, banks and 

private individuals to better plan their own aquaculture development or investment 

activities. On the commercial side, GIS can be used to reduce risks and for site 

selection. On the government side, GIS will be used increasingly for administration 

and regulation to promote the development of aquaculture. 

GIS use in aquaculture 

Aquaculture is a notably diverse activity, which requires secure access and rights to 

large areas of terrestrial and aquatic "space". Planning activities to promote and 

monitor the growth of aquaculture in individual countries (or larger regions) 

inherently take into account the differences among biophysical and socioeconomic 

characteristics from location to location. 

Biophysical characteristics 

● Water quality (temperature, dissolved oxygen, alkalinity, salinity, turbidity and 

pollution) 

● Water quantity (volume and seasonal profiles of availability) 

● Soil type (slope, structural suitability, water retention, capacity and chemical 

nature) 

● Climate (rainfall distribution, air temperature, wind speed and relative 

humidity) 

Socio-economic characteristics 

● Administrative regulations 

● Competing resource users 

● Market conditions (demand for fishing products, accessibility to markets) 

● Infrastructure support

● Availability of technical expertise 

GIS have been applied in aquaculture for the last 13 years. The scale of investigation 

varied greatly and GIS have been used at different planning levels with 

appropriately different spatial resolutions, depending on the intended purposes. GIS 

use in aquaculture has also varied significantly with regard to the complexity of the 

analytical methods used (i.e. ranging from simple map displays, simple and 

weighted combinations, to use of relatively sophisticated models). 

Continental studies of aquaculture potential have been made for Africa and Latin 

America. Likewise, several national or state-level studies have been conducted 

successfully. These studies are particularly useful for decisions related to: 

● environmental protection and sustainable resource use; 

● national planning activities; 

● assessing food security issues; and 

● investigating trade-offs pertaining to land allocation among different 

economic activities. 

GIS have also been used for site-level investigations after a preliminary choice of a 

site has been made. In conjunction with remote sensing and direct data collection, 

GIS can form the basis for continued monitoring of a site. 

Case study 

Following is a case study to illustrate basic GIS methodology applied for aquaculture 

in Asia. 

Microcomputer spreadsheets for the implementation of geographic information 

systems in aquaculture: A case study of carp in Pakistan 

This study was chosen because it shows a method of attaining limited GIS 

functionality through the use of a more readily obtainable, and usually more familiar, 

spreadsheet package. Spreadsheets are simply a two-dimensional array of cells, 

they can serve as an x and y coordinate system of geographical references, so they 

can be very suitable for simple GIS work, provided that the source data can be 

arranged in raster format. 

A 1:2 000 000 scale topographic map of Pakistan was used to trace an overlay 

which divided the country into 172 cells each representing a 75 km x 75 km area. The 

following factors were chosen as selection criteria relevant to the development and 

location of carp culture:

● Air temperature 

● Surface water availability 

● Soil type 

● Precipitation 

● Availability of underground 

water 

● Slope 

● Availability of fish seed 

● Distance from wholesale markets 

● Access to road transportation 

Data sources 

Most data for each of these 

factors were obtained from a 

series of maps published by the 

Pakistan government, though in 

some cases additional data were 

obtained from specific 

government ministries. 

Data for each factor, in each cell, were scored on a scale of 1 to 5, with 5 

representing the highest suitability of the parameter and 1 the lowest. The scored 

data were then entered into a spreadsheet package in a layout that spatially 

represented the country. After scoring the cells, a value was given to each factor 

according to how important it was seen to be compared to other factors. Values 

varied between 0 and 1. Scores were then multiplied by their relevant values and 

aggregated. The overall score represented the rating of the suitability of each cell 

for carp culture. 

Figure 1 shows the calculated 

sheet and Figure 2 is the 

graphic representation of 

Figure 1 using shaded blocks. It 

appears that the most suitable 

areas for carp culture are in 

central-eastern Pakistan where 

many tributaries of the River 

Indus converge across a wide 

flood plain. 

Figure 1. Scored cells showing suitability 

for carp culture in Pakistan

Figure 1. Scored cells showing suitability 

for carp culture in Pakistan 

Selected references for GIS uses in aquaculture 

Kapetsky, J.M. and C. Travaglia. 1995. Geographical information systems and 

remote sensing: an overview of their present and potential applications in 

aquaculture. In: Nambiar, K.P.P., Singh, T. (Eds.), AquaTech ’94: Aquaculture 

Towards the 21st Century. INFOFISH, Kuala Lumpur, pp. 187-208. 

Kapetsky, J.M. 1999. The development and training requirements for geographic 

information systems (GIS) and remote sensing (RS) applications in the Lower 

Mekong Basin (basin-wide) in relation to inland fisheries (including aquaculture). 

Assessment of Mekong Fisheries: Fish Migrations and Spawning and the Impact of 

Water Management Project (AMFP), Vientiane, Lao. P.D.R. AMFP Technical 

Report 4/99:1-83. 

Meaden, G.J. and J. M. Kapetsky. 1991. Geographical information systems and 

remote sensing in inland fisheries and aquaculture. FAO Fisheries Technical Paper. 

N. 318. Rome, FAO. 262p. 

Nath, S.S., J. P. Bolte, L. G. Ross and J. Aguilar-Manjarrez. 2000. Applications of 

geographical information systems (GIS) for spatial decision support in 

aquaculture. Aquaculture Engineering 23: 233-278.

Paw, J.N., F. Domingo, Z.N. Alojado and J. Guiang. 1994. Land resource 

assessment of brackish aquaculture development in Lingayen Gulf Area, 

Philippines. Technical Report of the Geographic Information Systems Application 

for Coastal Area Management and Planning, Lingayen Gulf Area, Philippines. Part 

III. International Centre for Aquatic Resource Management and International 

Development, Manila, Philippines. 

Tookwinas, S. and P. Leeruksakiat. 1999. Application of geographic information 

system (GIS) technique for shrimp farm and mangrove forest development in 

Chanthaburi Province, Thailand. Thai Marine Fisheries Research Bulletin 7:1-16. 

Tran Ngoc Tu and H. Demaine. 1997. Potentials for different models for freshwater 

aquaculture development in the Red River Delta (Vietnam) using GIS analysis. 

Naga. The ICLARM Quarterly 19(1): 29-32. 

Prepared by: 

Jose Aguilar-Manjarrez


Community-Managed Aquatic 

Resources 

Aquatic Resources as 

Common Property 

Community-Based Fisheries 

Management: An Approach to 

Sustainable Common 

Property Resource 

Management 

Economic Considerations for 

Community-Based Small- 

Scale Aquaculture in Oxbow 

Lakes 

Considerations in Co- 

Management of Capture 

Inland Fisheries and 

Aquaculture in Laos 

Culture-Based Fisheries in 

Reservoirs and Lakes in India 

Community Rice-Fish Farming 

in Bangladesh 

Marine Reserves and the Role 

of Local Government in Units 

in the Philippines 

Local Knowledge and the 

Conservation and Use of 

Aquatic Biodiversity 

Community-Managed Aquatic Resources

Aquatic Resources as Common Property 

A common property resource (CPR) is broadly defined as a natural resource in 

which a group of people has common user rights (not necessarily ownership rights). It 

is common for the resources of lakes, rivers, estuaries and marine areas to be 

considered as CPRs. 

Traditionally, CPRs are not open-access, that is available to anyone, but are subject 

to rules and conventions, often unwritten, of local communities. Particularly after 

colonization, such CPRs have come under State control, indigenous institutions have 

been marginalized and people’s participation in management of CPRs has 

frequently decreased.

CPRs form an integral part of the survival mechanisms for the poor and 

landless. Accessibility should, thus, be ensured and the resources protected. 

This usually requires community management. 

Why participatory management? 

● CPRs are community life-lines and almost all people have a stake in their wellbeing. 

● CPRs that could once sustain local communities may no longer be able to do 

so because they are over-stressed and mismanaged. 

● It is not desirable that an external agency takes control of resources that 

essentially belong to the community. 

Public awareness has to be raised and local people have to be involved in CPR 

management. 

Oxbow lakes: a CPR 

In Bangladesh, oxbow lakes have been managed by Local Management 

Groups to maintain equitable access to resources and to sustain the lakes. 

People-managed fish stocks 

In Southern Laos, local communities are now managing fish stocks in the 

Mekong River based on Conservation Zones and other management 

regulations. 

Why is CPR management difficult? 

● Conflict between different resource users, both within and outside the 

community. 

● Difficulty in excluding outsiders from resource use. 

● Uses of common resources are continually changing due to new opportunities 

and constraints. 

● Lack of appropriate knowledge or skills to manage resources effectively. 

● Livelihood constraints – even if local people know what they need to do to 

protect common resources, they are often dependent on these for income 

and have few livelihood alternatives. 

● Individuals are reluctant to curtail destructive activities if other people do 

them. The benefits of individual conservation actions are shared by the entire 

community, while the costs are incurred by the individual. 

● Management of common resources often occurs at different "scales" (local, 

municipal, national and regional) and the regulations at these different levels 

are sometimes conflicting. 

● Government responsibility for managing parts of the ecosystem often falls

under several different government sectors (e.g., mangroves may fall under 

forestry and fisheries) and policies and mandates of the different sectors may 

be conflicting. 

● Inequitable use and allocation of resources. 

Scale is important! 

The larger the resource and the more people are involved, the more difficult 

it is to have consensus. Larger systems may need to be managed in 

creative, possibly hierarchical ways to keep all users committed. 

Strategies for effective management 

Institutionalize people centered management programs. 

Ensure equitable distribution of benefits among all users. 

"Equity is not equality. Equity depends 

on having users agree that 

the arrangement is "fair"". 

How do you make CPR management effective? 

● Help people to organize themselves for collective action. 

● Involve the community in planning and development as they are the 

stakeholders. 

● Develop clear guidelines on user rights and responsibilities of each person in 

maintaining and managing the CPR. 

● Develop supportive policy and governmental regulatory mechanisms. 

● Help minimize conflicts between and within communities and with 

government. 

● Define boundaries around the area for local management, and legitimize 

community control through legislation. 

● Follow an interdisciplinary and systems approach to addressing management 

issues.

If resource users are not part of the "solution", they will be part of the 

problem. Ensure that "marginalized" users have a part to play, otherwise they 

may continue to exploit the resources without regard to the sustainable 

practices of the larger group. 

Guidelines for equity in resource 

use 

● People should have a 

share in the benefits from 

aquatic resources. 

● Duties and responsibilities 

must be clearly stated. 

● The role and responsibility 

of government must be 

clear and accepted by 

the stakeholders. 

● Means for enforcing 

regulations must be clear. 

● Unambiguous guidelines 

should define: 

– who may fish 

or undertake 

aquaculture 

activities, 

– where it can 

be done and 

– what 

methods are 

acceptable. 

Protected areas and CPRs 

Protected areas, marine protected areas and fish conservation zones establish CPRs 

but they are often associated with restricted use. The immediate benefits are in the 

"spill-over" to other areas. It may be necessary to designate other areas as being 

protected or regulated for communal use with sets of guidelines and enforcement 

measures. These efforts should be made in addition to other resource management 

schemes. 

Gender issues 

In places where women have limited rights to property or control of resources, CPRs

are often important sources of the resources they use. However, representation of 

women in local institutions and their training in the use of CPRs is disproportionately 

low compared to their use of CPRs. If the CPR is close to the households, women are 

more likely to participate. 

CPRs are often important sources of food for household consumption but the fish 

caught by men are usually destined for the market. Management of CPRs for 

aquaculture must be sensitive to how the resources are used. Men do not always 

recognize or identify such use. 

Prepared by: 

Gary Newkirk, Ian Baird and Karen McAllister

Community-based Fisheries Management: An 

Approach to Sustainable Common Property 

Resource Management 

Community-based fisheries management (CBFM) is recognized as a management 

approach for semi-closed lakes, known as beels. Beels are saucer shaped 

depressions representing perennial or seasonal water bodies. These common 

property resources are of relevance to aquaculture development efforts in 

Bangladesh. 

Four main methods of learning GIS 

Formal GIS degree or certificate programs 

Instructor-led training 

Internet learning 

Self-study 

Previously, only the influential and rich derived benefits from these semi-closed beels, 

because of the nature of the leasing system and the cost of lease. Resource poor

communities living around the beel were used as laborers (for cleaning, netting, 

guarding, etc.) but had no opportunity to derive benefits from this production 

system. They have never been involved in the management and development 

programs of the beels. 

Necessary initiatives to ensure community involvement 

Identify the direct beneficiaries using various information sources and 

hold consultations with all stakeholders in the community 

Organize them into groups (15-30 members in each group) 

Hold regular meetings 

Initiate savings (weekly/fortnightly) 

Trainings (discussions) 

Participatory resource-use analysis 

Participatory planning for collective actions 

Activities: 

Fisheries (stocking, nursery, hatchery) 

and 

Non-fisheries income generating activities (IGAs) 

for individuals and groups 

Equitable distribution of benefits 

Institutionalization 

A community-based fisheries management approach, by its objectives, emphasizes 

establishing fishing rights for the resource poor community. After accessing these 

fishing rights, the community develops a sense of ownership helps them improve their 

livelihood.

Training areas 

Case Study 

Under the community-based fisheries management (CBFM) program, 

CARITAS-Bangladesh organized eight fisher groups (189 members) among 

the resource poor surrounding the Rajdlhala Beel in Purbadhala Thana, 

Netrokana district. 

Activities of CARITAS included adult literacy, trainings, financial support for 

lease money (interest free) and credit for income generating activities. Prior 

to the CBFM initiative, an influential person living far away from the beel 

acquired lease rights to the resource and local community fishers worked as 

laborers. 

Now the farmer laborers have been able to establish their fishing rights 

through a three-year lease under CBFM. The community became skilled in 

planning, beel management, small indigenous species (SIS) conservation 

and other income generating activities through the different trainings of 

CARITAS. They organized a beel management committee (BMC) by 

themselves, with members from each group. The community constructed a 

facility or center for meetings, trainings, guarding and fish landing. They reexcavated 

two ponds near the beel which they use as nursery ponds. They 

accumulated savings valued at US$2,500 used as counterpart for various 

fisheries and non-fisheries activities. CBFM presented opportunities to the 

community by providing nutritional support, economic benefit and a feeling 

of unity and ownership of a resource. The community has also taken 

responsibility for biodiversity conservation. 

Now that the three years are over, the community has taken another lease 

for three years and is negotiating for longer lease periods. Since they 

invested money for the development of the resources, CARITAS is giving 

them priority hoping that this community will act as a model and a source of 

inspiration for other communities in managing their own beels in a 

sustainable manner. 

● Value added awareness 

● Potentials of the resource 

● Biodiversity of the resource 

● Resource use analysis 

● Participatory planning 

● Distribution of responsibilities 

● Social awareness 

● Adult literacy 

● Simple accounting 

● Group management 

● Gender 

● Equity

Actions and resulting benefits to communities

Constraints 

High lease value 

The normal system is to lease out the beel for three years with a 25% increase in cost 

for the first year and a 10% increase for years two and three. CARITAS is assisting the 

communities bargain for a longer lease period. 

Lack of demarcation 

Water resources are becoming scarce with time (siltation, drought, etc.) but 

government records are not updated to this effect. Leasing out dry areas to 

agricultural farmers, who continue their activities during the fishing season, threatens 

the breeding of small indigenous species (SIS). Fishers giving lease money for 

agricultural land, ultimately create social conflicts. 

Tenurial issue 

Resource development, especially resource generation, demands some sort of 

investment (dike, nursery, hatchery, landing place, etc.) and sacrifice (sanctuary, 

fishing ban). As the maximum tenure for more than 10,000 khas plots (government 

owned land/water) is only three years, it appears difficult to initiate resource 

generation or resource development. 

Strategies to overcome constraints

Community responsibility 

A democratic process of voting 

to organize a management 

committee is necessary to 

manage activities like general 

meetings and deal with bank 

accounts, leasing authorities 

and other stakeholders, etc. A 

new committee might take 

some time to work out a system 

that works best. 

Community responsibility is 

among the most important 

issues for the khas plots management -- from planning to distribution of benefits. 

Communities must have specific livelihood development projects as well as a 

resource development plan. One will not work without the other. 

Conflicts 

– Influential rich vs. resource poor 

– Various water-users (aquaculture, agriculture, etc.) 

– Inter-sectoral 

– Outsider vs. community 

Replication of the approach 

Hopes for the future appear to be bright, however. CARITAS-Bangladesh has 

initiated two projects, with the implementation strategy being based on the 

experience of the CBFM, community-based fisheries management project. The 

projects are: Management of Aquatic Ecosystem through Community Husbandry 

(MACH) and Sustainable Aquatic Resources Management (SARM). 

CBFM has proven to be a successful strategy and is becoming popular. Even the 

country’s two significant development projects – Sustainable Environment 

Management Project (SEMP) under the Ministry of Environment and Forest and the 

Fourth Fisheries Project under the Ministry of Fisheries and Livestock – have been 

launched based on the same strategy.

Economic Considerations for Community-Based 

Small-Scale Aquaculture in Oxbow Lakes 

Oxbow lakes, including the fish and the water forming part of it, are common 

properties. With its bountiful resources, proper management of these lakes would 

yield greater benefits to the surrounding poor communities. In managing Oxbow 

Lakes, the dynamic partnership between the fishers and government should be 

nurtured. Non-government organizations (NGOs) can play a catalytic role by 

building up the capacities and interests of local communities.

Security of tenure 

● To establish a community-based fisheries management institution, fishers 

should be granted "secured use right" to oxbow lake management on a longterm 

lease. 

● Standardized annual lease fees should be imposed on members of the Lake 

Management Group (LMG) to avoid an open-access type of fishery.

Infrastructure 

Initially, the Oxbow Lakes were leased to the community for seven years. 

The successful management of the Oxbow Lakes led to a 50-year 

guaranteed lease by the government to community institutions. 

● Fishers need government/donor assistance for the enormous initial investment. 

● Infrastructure development such as screen installation, water control structures, 

community meeting shade and roads, among others, has to be done. 

● Annual repair and replacement by the fishers of screen are necessary. 

Institutional credit 

● Poor fishers should have access to credit facilities to cover the cost of inputs 

and maintenance. 

Employment generation 

● One to three fishers per hectare could be involved in fishery management. 

● Continuous stocking, harvesting and other fishery-related activities can 

generate employment and increase production. 

Marketing 

● Fish marketing costs range from 3-10% depending on the mechanism and 

distance of markets. 

● Marketing network information is necessary to get competitive prices. 

● Timing of fishing is important in relation to local and wholesale markets. 

Marketing costs were low in Oxbow Lakes where the fishers used a rotation 

in involving fishers groups to market harvest. (Rahman, M.M., 1996.) 

Better use of land resources 

● Construction of small ponds could increase production and generate 

employment during dry season when the Oxbow Lake catchment area 

becomes dry. 

● Dikes can be used for vegetable cultivation. 

● Afforestation program can be undertaken with high-value timber tree. 

● Pipe culverts should be installed to allow the nutrient and washings to go into 

the lake.

The OLP II constructed a series of ponds with the help of the World Food 

Program. Women were involved in the fish culture. Six women assigned per 

hectare. Some ponds were allocated to LMGs for fingerling nursery. 

Formation of homogeneous group 

● Government and NGOs must facilitate the formation of a wider communitybased, 

fishery management forum. 

● The user community should form a cohesive and homogeneous group based 

on social and economic criteria. 

LMCs are authorized to spend US$10 without prior permission of the general 

membership. In the monthly general meeting, the LMC has to propose a 

planned expenditure and get approval from 75% of the LMG members. It 

also has to present detailed expenditure for the previous month and 

current cash status. The bank account is managed by three co-signees of 

the LMC. In spite of that, a participatory audit team was constituted with 

representatives from the LMC, NGO (BRAC) and DoF. This participatory 

method helped reduce unseen expenditure and increased confidence. 

Income and expenditure 

Transparent record keeping on an annual basis is essential to establish mutual trust 

among the fishers if community institutions are to remain sustainable. 

Annual physical and financial planning 

An annual physical and financial plan is important in community-based Oxbow 

Lakes fishery management. Planning includes issues such as fingerling stocking, 

harvesting, money flow, credit repayment, and income distribution and saving. 

Introduction of continuous stocking and harvesting 

● Continuous stocking and harvesting generate employment and increase 

production. 

● Fishing is prohibited during the rainy season, i.e., July to September, to allow 

fish to grow. 

● Annual planning and related activities can be undertaken during lean periods. 

● The stocking size is 30-40 g each, i.e., 25-35 fingerlings/kg. 3-4.5 thousand/ha. 

● Harvesting size (within 12 months of stocking) is 30-40 cm in length (400-700 g). 

Yields could be 2 t/ha.

Several Oxbow Lake community group annual planning discussions 

resulted in very innovative and fruitful ideas for disseminating a new culture 

practice of the Oxbow Lakes fishery (Rahman, 1995). Annual plans are 

prepared at the beginning of each financial year that starts in July. 

Selection of species 

Species selection is important if local demands are to be met to facilitate marketing. 

In OLP II, small lakes (80 ha) was US$302. 

Economic size of Oxbow Lakes 

Larger Oxbow Lakes tend to have lower fishery related net income per hectare 

compared to smaller lakes. 

Equitable distribution 

Equitable distribution and cost sharing are fundamental in sustaining communitybased 

aquaculture. 

Entrepreneurship 

An entrepreneurship attitude is necessary for taking the initiative in adopting and 

innovating new practice, thus creating responsible aquaculture. 

Prepared by: 

Mokhlesur Rahman

Considerations in Co-Management of Capture 

Inland Fisheries and Aquaculture in Laos 

Basket-bundle fish trap – one of the many varieties of traditional fishing gears used in Laos 

Freshwater fish and other inland aquatic animals are important sources of food and 

income for rural people living adjacent to the Mekong River and its tributaries, 

including those in the Lao People's Democratic Republic (Lao PDR or Laos). The 

Mekong River, which runs through Laos, supports a diverse and productive aquatic 

system. Nowhere in Laos are wild capture fisheries more important than in Khong 

District, Champasak Province, where most of the over 65,000 residents are semisubsistence 

rice farmers and small-scale fishers living on numerous islands in the 

middle of the Mekong River or along its banks. 

Inland water bodies are important to small-scale fisheries in Khong. The vast majority 

of the aquatic animals consumed and traded by Lao people are caught in the wild . 

Aquaculture is virtually absent in the district. It is not commonly or traditionally 

practiced in Laos, although a few ethnic groups have historically engaged in a 

limited traditional rice-fish culture using wild species. The Mekong River Basin in Laos 

has a very high aquatic biodiversity and its conservation, as well as sustainable 

management, is important to the livelihoods of local people. 

The majority of rural people in remote areas still rely more on capture fisheries 

than on aquaculture.

However, the importance of wild capture 

fisheries in increasing the amount of fish 

available to the local population has often 

been overlooked by development agencies 

both within and outside Laos. It has sometimes 

been assumed that wild capture fisheries are 

declining and that it is not feasible to restore 

natural stocks of aquatic animals. It has also 

been argued that an increasing population is 

likely to make it impossible for wild capture 

fisheries to meet local demand for fish 

products. Aquaculture has been assumed to 

be the only realistic and viable way to increase 

fish availability in rural areas. As a result, 

aquaculture has received most of the funding 

and only a few agencies have supported the 

management and improvement of wild 

capture fisheries in Laos and other countries in 

the Mekong Basin. The situation appears to be 

changing, however, as developers begin to 

realize the importance of wild capture fisheries. 

Adopting natural aquatic co-management 

regimes is a cost-effective way of improving 

natural resource management, increasing fish 

productivity, human nutrition, increasing community solidarity and reducing rural 

poverty. 

Natural aquatic resource co-management in Khong District, Champasak Province 

In 1993, the Lao Community Fisheries and Dolphin Protection Project (LCFDPP) was 

established to promote the conservation and sustainable use of aquatic resources in 

the mainstream Mekong River along with adjacent seasonal streams, rice fields, and 

natural depressions. The LCFDPP attempted to help locals improve their quality of life 

while also improving environmental conditions, the basis for aquatic productivity. This 

led to the establishment of a natural aquatic resource co-management program in 

cooperation with the local government. Communities were given the authority to 

pursue their own unique sets of co-management regulations through a participatory 

and voluntary process.

Co-management is the collaborative and participatory process of regulatory 

decision-making among representatives of user-groups, governments and 

research institutes. 

The direct stakeholders involved in the co-management system in Khong 

district are: 

1. the villages and all its members (i.e., both men and 

women); 

2. the government, including line agencies responsible for 

aquatic resources; and 

3. NGOs with projects supporting co-management in Khong 

district. 

Communities in Khong District are relatively homogeneous and economically 

unstratified, leading to a relatively small number of stakeholders compared 

to many places. 

Between 1993 and 1999, 63 villages in Khong District established co-management 

regulations for managing aquatic resources that were recognized by the 

Government in the vicinities of their communities. This enabled individual 

communities to establish 68 separate Fish Conservation Zones (FCZs), or fishery "notake 

zones" in the mainstream Mekong River.

Results from a rapid survey in 14 randomly selected villages in Khong District 

in 1997 showed that 94% of the families in the district took part in subsistence 

fisheries; an average person in Khong caught 62 kg of fish over a 12-month 

period in 1996 - 1997. Fish products were the most important source of animal 

protein consumed in about 80% of the meals in Khong and the total annual 

fish catch estimate for the district was 4,000 metric tons. Over US$ 1 million of 

fish products originating from Khong were sold to local and distant markets; 

the average family generated the equivalent of US$ 100 per annum from 

selling fish caught by using small-scale fishing gears such as gill nets, longlines, 

castnets and various kinds of traps. 

The FCZs are among the most important elements of the co-management system, 

although other regulations have also been adopted, such as: 

1. Banning the use of fish traps in streams at the beginning of the rainy season when 

some fish species migrate up to rainfed rice fields, natural depressions and other 

wetlands. 

2. Prohibiting the capture of snakehead fish (Channa striata or pa kho, in Lao) fry with 

scoop nets. 

3. Restricting the harvesting of frogs (Rana spp. or kop, in Lao), especially during the 

spawning season. 

4. Restricting a number of fishing gears and methods, including spearing fish at night 

and water banging fishing. 

5. Protecting wetland habitat. 

The aquatic resource co-management program in 

Khong has been very successful. Local people believe 

that fish stocks and catches have increased due to the 

co-management regulations, including the 

establishment of FCZs. Village solidarity has also 

improved. This has all been done at a very low cost to 

donors and the Government, since villagers do most of 

the work themselves. Although technical and 

biological answers to how the various management 

strategies, including the establishment of FCZs, led to 

increased fish stocks, villagers are already convinced 

that the systems work and they intend to continue 

implementing them indefinitely. Several reviewers have 

also concluded that the program has been successful 

and appropriate (see Meusch, 1997; Hogan, 1997; 

Cunningham, 1998; Baird and Flaherty, 1999; 

Chomchanta et al., 2000).

Fish spearing with lights at night 

has been banned in many 

communities in Khong 

Some key elements of the established systems include: 

1. Each village has its own unique set of regulations based on local social and 

environmental conditions. 

2. The local government fully supports the co-management process and has 

helped promote it. 

3. The regulations created can be amended according to changing social and 

environmental circumstances. Flexible management regimes can keep the 

systems relevant. 

4. The local Government carefully ensured that resource-poor communities were 

not excluded from fishing in richer areas, where co-management regulations 

apply, to reduce conflict between communities. However, resource-poor 

communities must follow the same regulations that the host communities have 

imposed on themselves.

The poor often do not hold tenure to land and water resources that is 

generally required before aquaculture can be developed. 

Special efforts should, therefore, be made to ensure that poor and 

disadvantaged groups are not denied access to natural aquatic resources 

or that the natural resources they depend on is not degraded due to the 

development of aquaculture. 

Environmental health concerns regarding aquaculture development 

Aquaculture provides a wide-range of benefits to people and the environment, but it 

can also cause ecological problems. We now know that some types of aquaculture 

(e.g., large-scale commercial shrimp farming) are unsustainable and destructive. 

Inland shrimp farming has become a threat to the environment in Thailand, as they 

added large amounts of salt to ponds in inland areas. However, over the past 

decade, shifts in research priorities from intensive to extensive and semi-intensive 

culture have resulted in breakthroughs in small-scale inland aquaculture. 

Small-scale extensive and semi-intensive inland aquaculture needs to be 

carefully managed and regulated in order to ensure that it does not cause 

environmental and social problems. 

Aquaculture and wild fish stocks often 

compete for the same limited 

resources (e.g., land, water and 

nutrients). Aquaculture has to be 

developed without jeopardizing the 

natural resources that support 

important capture fisheries. 

The introduction of exotic aquatic 

animals into the wild through 

aquaculture has sometimes resulted 

in socio-economic benefits to rural 

people, especially over the short run. 

However, it could also pose serious 

problems, especially over the long term. For example, the golden apple snail, 

introduced for aquaculture, has become one of Laos’ most serious rice pests, 

especially in the Vientiane area. This is also true for other countries including the 

Philippines. At present, the common carp (Cyprinus carpio) and tilapia (Oreochromis 

spp.) are two of the most commonly farmed fish species in Laos and other countries 

in the Mekong Basin. Both species, which are not native to the Mekong, are 

suspected of causing serious ecological damage to native fish species and aquatic

communities in other parts of the world. 

Genetically modified organisms (GMOs) have the potential to damage the 

environment and biodiversity. It seems logical to expect that introducing GMOs and 

non-native species into natural waterways will eventually lead to ecological changes 

that might adversely affect native strains and species. History indicates that it is 

reasonable to expect that fish farmed over many years will eventually escape or be 

released into the wild. Therefore, precautionary measures should be taken in 

introducing exotic species for aquaculture. 

There are probably more than 1000 indigenous fish species in the Mekong 

River Basin. This means some species might be suitable for aquaculture. The 

effort has to be made to investigate and develop their potential. 

More research should focus on identifying and promoting native fish species for 

aquaculture. For example, the silver barb (Barbodes gonionotus) is a native species 

bred artificially in Laos and found to be extremely suitable for pond culture in the 

country (FAO, 1999). The giant carp (Catlocarpio siamensis) has shown promise as an 

aquaculture species in Cambodia. 

Freshwater fish aquaculture can 

adversely affect the environment by 

causing the alteration and 

degradation of natural habitats. For 

example, streams have sometimes 

been dammed to create small 

reservoirs where fish can be raised. 

While the impact of blocking a small 

stream is not likely to be as severe as 

that of damming a large river, fish 

migrations and habitat usage can 

still be affected. 

Many freshwater ecosystems such as lakes, rivers and wetlands are some of the most 

endangered in the world. Wetlands have sometimes been converted into 

aquaculture ponds, causing the loss of valuable wild fish habitat. Habitat conversion 

may involve the dredging of wetlands, removal of surrounding vegetation, 

fragmentation of water bodies, or diversion of water from other wetlands. More care 

must be taken to internalize costs associated with aquaculture development and 

reduce the impact on the environment. 

Another potential problem with aquaculture relates to the quality of water released 

into the natural environment from ponds and cages. Although there are not yet 

many examples from Laos, chemicals and antibiotics used in aquaculture can 

contribute to high levels of pollution. Intensive aquaculture generally uses the least

amount of land and water, but has the most potential to cause serious pollution 

problems due to high inputs and high waste output. Pollution caused by 

aquaculture, as well as by other industries, often contributes to various animal health 

problems such as the spread of viruses that threaten both wild and cultured animals. 

Epizootic Ulcerative Syndrome (EUS) is one of the most serious diseases affecting both 

cultured and wild fish in inland areas in Asia. Native fish species inhabiting rice field 

and small wetland have been especially devastated by EUS for over 20 years in 

mainland Southeast Asia, including Laos, leading to massive protein and income 

losses for local people. While more research on EUS is needed, some researchers 

believe that its spread was facilitated by the transfer of aquaculture fish species into 

the region. 

The ecological footprint concept, developed to determine the area necessary to 

sustain current levels of resource consumption and waste discharge, is useful when 

considering the ecological impact of aquaculture development. Some forms of 

aquaculture have a large ecological footprint while others have much smaller ones. 

For example, carnivorous species like shrimps and catfish have a large ecological 

footprint because they rely heavily on external food sources, such as fish meal 

obtained from capture fisheries. Therefore, it generally takes much more weight in fish 

to raise carnivorous aquatic animals compared to the final harvest weight. This leads 

to an overall reduction in animal protein available to an increasingly populous world. 

Ecological footprint 

As an example of how the ecological footprint concept works, Folke et al. 

(1998) estimated that carnivorous fish farming in cages is sometimes 

dependent on marine ecosystem areas 10,000-50,000 times the size of the 

cages used for producing the fish. Additional area is also required to absorb 

wastes from the cages. However, herbivorous species, like the silver barb, are 

much less dependent on external sources of food and, therefore, have a 

smaller ecological footprint. In addition, aquaculture that combines species 

from different trophic levels, applies ecocyclic production, and generates 

multiple services and outputs can reduce the ecological footprint 

substantially. 

Rice-fish culture can result in significant environmental benefits resulting from the 

ability of fish to help reduce agricultural pests and vectors that affect human health. 

However, when high dikes are built to keep the fish stocked into rice fields from 

escaping, an important habitat previously available to wild fish is lost. Measures 

should be taken to allow wild fish to enter rice fields. Denying them access can lead 

to declines in fish stocks outside the fields, affecting poor people who rely on the 

harvest of the wild fish that need the rice field habitat for part of their life cycle. 

Aquaculture can have a negative impact on natural aquatic communities through 

the collection of seed from the wild, especially when intensive collection is done, and 

when aquatic animals are collected from the wild to supply feed for carnivorous and

omnivorous cultured species. 

Social and equity considerations 

It seems likely that there have been occasions when development agencies have 

inadvertently helped better-off farmers adopt and benefit from aquaculture while 

poor fishers who relied on the natural resources degraded by aquaculture, registered 

a net loss due to aquaculture development. Some commercial aquaculture 

programs have negative impacts on the rural poor in terms of resource competition, 

altered familial work patterns, increased unemployment and the degradation of 

nutrition. 

In Laos, it has been found that aquaculture often leads to the privatization of 

common property resources by the relatively powerful and influential. A 

good example is found in the Oupaxa Village in Khong District. There, a 

natural depression previously fished by everyone in the community became 

privatized a few years ago after one of the more powerful members of the 

community decided he wanted to try farming fish in the natural pond. 

Essentially, a resource that used to benefit the whole community, including 

the poor, was taken and given over to a single well-off family. The 

privatization of common property in the name of promoting aquaculture is 

one of the most serious problems aquaculture advocates must address. 

Sadly, aquaculture has sometimes been used to justify either degrading wild fish 

stocks or not putting sufficient resources into the sustainable management or 

restoration of naturally occurring aquatic communities. For example, advocates of 

large-scale hydroelectric dams often claim that the damage the infrastructure does 

to natural aquatic communities, including productive wild-capture fisheries, can be 

justified, since aquaculture can be introduced to mitigate losses of fish protein and 

income to local people. 

The capital-intensiveness of certain aquaculture practices can force small farmers to 

go into debt for inputs. A debt cycle is likely to develop in aquaculture if the 

technology packages for the rural poor include too many inputs like feeds and 

fertilizers. Aquaculture may indeed lead to increased production but malnutrition

might persist. Moreover, aquaculture often requires a sustained investment in terms of 

seed, feed and other inputs, while wild fish are natural capital that farmers and fishers 

can benefit from at a low cost and risk, and sometimes without any investment. 

Conclusion 

Aquaculture can benefit wild capture fisheries by providing fishers with an 

alternative source of protein and income, which may help reduce 

overfishing and restore depleted stocks. But using aquaculture as an excuse 

for neglecting natural fish stocks is a problem that needs to be seriously 

addressed. 

Aquaculture is an important means for producing increased amounts of affordable 

aquatic protein, especially when herbivorous and omnivorous species are cultured 

on a small-scale and as a part of integrated farming systems. While there is no space 

here to review the benefits of aquaculture, it is acknowledged that it has the 

potential to benefit society and the environment. This paper does not claim that 

natural aquatic co-management will be the most appropriate form of intervention in 

particular areas. Many social and environmental factors need to be considered, and 

individual circumstances are generally complex. Aquaculture can benefit local 

people in rural areas, but we need to be cautious and careful in promoting it. While 

aquaculture activities are often essentially environmentally and socially benign, they 

can sometimes cause or increase various kinds of environmental and social 

problems, especially when precautions are not taken. We need to be especially alert 

to problems and address them at an early stage, or even prevent their happening. 

.Aquaculture will continue to be developed in Southern countries like Laos. 

Therefore, it is necessary to push for the adoption of more sustainable forms 

of aquaculture, rather than deny its role in rural development. Essentially, 

precautionary measures should be taken in developing aquaculture, 

although such measures will certainly slow the growth of aquaculture over 

the short term. However, careful promotion should benefit aquaculture in the 

long term by silencing its critics through improved practices.

Aquaculture in Laos and other 

countries in the region should 

not be regarded as the only 

means for increasing fish 

production. Governments must 

also allocate resources to the 

management of wild fisheries. 

The promotion, conservation 

and sustainable management 

of naturally occurring aquatic 

resources are important as 

many rural people still rely 

primarily on nature for their 

subsistence and welfare. Wellmanaged 

fish stocks can help to 

take up the slack when famines, 

flooding and drought cause 

land-based crops to fail. They are especially important for the poorest of the poor 

and subsistence-oriented people living in rural areas. Many types of aquaculture are 

useful in improving the livelihoods of local people but, as development advocates, 

we need to remain critical regarding their benefits. Aquaculture is not a panacea for 

the wild capture fisheries problems that we are facing worldwide. It cannot and 

should not be seen as a substitute for sound fisheries management allowing the full 

participation of all stakeholders. Aquaculture is but a part of the equation. How it is 

extended and promoted will indicate whether it is helpful to the rural poor and the 

environment or not. 

While it is admirable that efforts have been made to integrate small-scale 

aquaculture with other agricultural activities, we now need to advance further by 

considering aquaculture in the broader overall context of natural aquatic resource 

management and livelihood opportunities, including non-farm options. 

References 

Chomchanta, P., P. Vongphasouk, S. Chanrya, C. Soulignavong, B. Saadsy and 

T.J. Warren. 2000. A Preliminary Assessment of Mekong Fishery Conservation Zones 

in the Siphandone Area of Southern Lao PDR and Recommendations for Further 

Evaluation and Monitoring. Final Report. Prepared for The Living Aquatic 

Resources and Research Centre (LARReC), Vientiane, Lao PDR, 32 p. 

Cunningham, P. 1998. Extending a Co-Management Network to Save the 

Mekong's Giants. Mekong Fish Catch and Culture, Mekong River Commission, 

Bangkok, 3(3): 6-7. 

FAO. 1999. Fishery Country Profile: The Lao People's Democratic Republic. 7 p.

Folke, C., N. Kautsky, H. Berg, A. Jansson and M. Troell. 1998. The Ecological 

Footprint Concept For Sustainable Seafood Production: A Review. Ecological 

Applications, 8(1) Supplement: 563-571. 

Hogan, Z. 1997. Aquatic Conservation Zones: Community Management of Rivers 

and Fisheries. Watershed, TERRA, Bangkok, 3(2): 29-33. 

Jentoft, S., B.J. McCay and D.C. Wilson. 1998. Social Theory and Fisheries Comanagement. 

Marine Policy, 22(4-5): 423-436. 

Meusch, E. 1997. Participatory Evaluation Workshop of the LCFDPP. AIT Aqua 

Outreach Report. 7 p. 

Prepared by: 

Ian G. Baird

Culture-Based Fisheries in Reservoirs and Lakes in 

India 

In many developing countries, aquaculture has been given a high priority, either to 

improve the availability of protective food or to cater to overseas trade. However, 

the unchecked growth of aquaculture ventures that violate environmental norms 

can open the floodgate to new concerns, as evident in the recent Asian prawn 

culture experience. Living aquatic resources, although renewable, are not infinite. 

They need to be managed in a sustainable manner. In this context, enhancements, 

especially culture-based fisheries, assume significance. Welcomme (1996) considers 

enhancements as the fastest expanding sectors of freshwater fish production, which 

currently contributes about 20% to the inland fish production in the world (Lorenzen, 

2000). 

Most nations are reported to be exploring the possibilities of utilizing inland 

lakes and reservoirs to improve or commence culture-based fisheries. This 

should be attractive to most environmental groups as it entails little or no 

manipulation of the environment (De Silva, 2000). The social relevance of 

culture-based fisheries is equally important. Unlike intensive aquaculture 

systems, culture-based fishery is practiced in community or common 

property regimes, where the benefit accrued from the increased 

productivity is more equitably distributed. 

Growth in the marine sub-sector in India has slowed down considerably over the 

years while the share of inland fisheries has increased. Nearly one million tons of 

inland fish production in India is attributed to culture-based fishery and other forms of 

enhancement practiced in reservoirs, small irrigation impoundments and floodplain

wetlands. 

Reservoirs 

In broad terms, the small reservoirs are managed as culture-based fisheries, while 

medium and large reservoirs can be considered as more akin to stock and species 

enhancement. However, there cannot be a thumb rule to differentiate the two 

systems on the basis of reservoir area alone. Fishing conditions, shallowness of the 

reservoir and natural recruitment are major factors that determine whether capture 

or culture-based fishery is followed. 

Reservoir resources in India 

Category Number Area (ha) 

Small (5000 ha) 56 1,140,268 

Total 19,370 3,153,366 

Culture-based fisheries of small reservoirs 

More than 70% of the small reservoirs in India are small irrigation impoundments 

created to store stream water for irrigation. They either dry up completely or retain 

very little water during summer, thus ruling out the possibility of retaining brood stock 

for recruitment. Culture-based fishery is the most appropriate management option 

for small reservoirs in India. 

Species selection 

Culture-based fisheries of small reservoirs in India largely center around the three 

species of Indian major carps -- Catla catla, Cirrhinus mrigala and Labeo rohita -- 

because many Indian States have the technical capability to produce carp seed. 

The Indian major carps have impressive growth rates and their feeding habits are 

suitable for utilization of various food niches. Stocking of Indian major carps has 

always been very effective in small reservoirs. 

Stocking rate

A large country like India, with many water bodies to stock, has an inadequate state 

machinery to meet the stocking requirements of all its reservoirs. The main 

considerations in determining the stocking rate are growth rate of individual species, 

mortality rate, size at stocking and the growing time. As a result of the National 

Consultation on Reservoir Fisheries, the Government of India adopted recently 

Welcomme’s (1976) formula in calculating the stocking rate for small reservoirs. 

Management of medium and large reservoirs 

Since large and medium reservoirs are managed on the principles of enhancement 

of capture fisheries, the main focus of management is on conservation of habitat to 

allow the natural recruitment and growth of the target species. Stock monitoring is 

achieved through the maneuvering of fishing effort and following mesh size 

regulations. Introduction is undertaken to correct imbalances in the species 

spectrum, while stocking is done as a temporary measure to compensate for 

recruitment failure. 

Stock enhancement 

Stocking attempts made in 

medium and large reservoirs were 

successful when the stocked 

fishes bred and propagated 

themselves (Sreenivasan, 1984). In 

a number of reservoirs, even 

repeated stocking for more than 

10 years did not make any impact 

because the fish did not breed. 

The increase in fish production 

due to recapture was not enough 

to recover the expenditure 

involved in stocking. Thus, the 

main aim of stocking efforts in 

medium and large reservoirs should be stock enhancement rather than recapture 

(unlike the culture-based fisheries). 

Species enhancement 

Species enhancement aims to augment the species range by adding fish species 

from outside. These introductions colonize all the diverse niches of the biotope. The 

three Indian major carps, Catla catla, Labeo rohita and Cirrhinus mrigala, were

eing stocked in the peninsular reservoirs for the last five decades. This was done 

despite the fact that the peninsular rivers have habitats distinctly different from those 

of Ganga and Brahmaputra where fishes are indigenous. In some of the south Indian 

reservoirs, they have established breeding populations. The hallmark of the Indian 

policy on stocking (introductions in the case of peninsular reservoirs) is heavy 

dependence on Indian major carps. 

Introduction of exotic species 

The government policy clearly disallows stocking of exotic fish in reservoirs to prevent 

any adverse impact on the biodiversity. However, tilapia (Oreochromis 

mossambicus), silver carp (Hypophthalmichthys molitrix), grass carp 

(Ctenopharyngodon idella), and three varieties of common carp (scale carp 

Cyprinus carpio communis, mirror carp C. carpio specularis, and leather carp C. 

carpio nudus) have gained entry into Indian reservoirs either by accident or 

deliberate stocking. A spectacular performance of silver carp is recorded in the 

Gobindsagar reservoir (Himachal Pradesh) where, after an accidental introduction, 

the fish formed a breeding population and brought about a phenomenal increase 

in fish yield. Silver carp was instrumental in enhancing production of Gobindsagar 

from 160 t in 1970-71 to more than 1,000 t at present. However, this high yield was at 

the cost of Catla catla. Moreover, as the people did not accept the exotic fish, this 

resulted in social and economic problems. 

Fish production 

The average national yield from 

culture-based fisheries of small 

reservoirs in India is nearly 50 kg/ha 

(Sugunan and Sinha, 2000), which is 

low (Sugunan, 1997) compared to 

other countries in Asia and Latin 

America such as China (743 kg/ha), 

Sri Lanka (300 kg/ha) and Cuba 

(100 kg/ha). Even a modest 

increase in yield can push up the 

production of small reservoirs to at 

least 0.15 million t, against 

the present level of less that 0.07 

million t. Similarly, the medium and 

large reservoirs can add another 

0.13 million t. Producing 0.2 million t of fish from aquaculture would entail creation of 

100,000 ha of new ponds at a cost of 20 billion INR (US$ 440 million). Considering that 

this yield enhancement can be achieved at a much lower cost, on sustainable and 

eco-friendly terms, reservoirs should receive adequate priority in future plans for 

inland fishery development in India.

One of the reasons for the low yield is under-stocking. There are 900 hatcheries 

across the country producing more than 18,000 million fry of Indian major carps 

annually. However, most of the fry produced in the hatcheries go to aquaculture 

managed by the private sector. The government and cooperative societies, which 

manage the reservoir fisheries, do not have enough infrastructure to produce the 

required number of fingerlings. 

Recent trends 

Efforts made by the Central Inland Capture Fisheries Research Institute (CIFRI) in many small 

reservoirs across the country have demonstrated the efficacy of culture-based fisheries. For instance, 

in Aliyar reservoir (Tamil Nadu) fish yield increased from 35 kg/ha to 194 kg/ha. Successful stocking 

has also been reported from a number of small reservoirs in India. 

A recent World Bank-assisted reservoir fisheries development 

project in India confirmed the validity of using Indian major 

carps in the culture-based fisheries of small reservoirs. The 

project, covering 78 reservoirs (24,613 ha) in three states, 

involved erection of pen nurseries in the reservoirs to ensure 

that the fish seed was reared to at least 100 mm in size before 

stocking. Loan was provided to cooperative societies to buy 

boats and nets. A perceptible relation between stocking and yield was 

obtained. 

Floodplain wetlands 

Wetlands located at the floodplains of major rivers form an important fishery 

resource in the northern and northeastern states of the country. Known as beels, 

boars, pats, and chaurs, they spread over more than 200,000 ha of surface area in 

the eastern and northeastern regions of the country. Studies conducted by the CIFRI 

in the past 15 years have shown that fish yields from the floodplain wetlands of West 

Bengal can be raised to 1,000-1500 kg/ha/yr from its present level of only 100-150 

kg/ha/yr by adopting culture-based fisheries (CIFRI, 2000). 

There are two kinds of floodplain wetlands, namely, open and closed, depending on 

their connection with the parent river. They have different patterns of community 

metabolism. 

Fisheries of the open lakes

The open type of floodplain wetlands is a typical continuum of rivers, where the 

management strategy is essentially akin to riverine fisheries. In capture fishery 

management, the basic approach is to allow recruitment by conserving and 

protecting the brooders and juveniles. Therefore, an insight into population dynamics 

including recruitment, growth and mortality is very much essential. Identification and 

protection of breeding grounds, free migration of brooders and juveniles, and 

protection of brood stock and juveniles through conservation measures are 

important. Common strategies followed are summarized as: 

● Increase the minimum mesh size to catch fish at the size of at least 500 g 

● Increase or decrease the fishing effort to maintain maximum sustainable yield 

● Observe the close season (usually during the southwest monsoon) to protect 

the brood stock 

● Maintain the diversity of the gear that comprise a number of indigenous 

designs (fish aggregating devices, traps, lift nets, dip nets, cast nets, etc.) 

● Selective augmentation of stock, only if unavoidable 

Culture-based fisheries of the closed lakes 

Culture-based fishery is most suitable for closed lakes. In culture-based fishery, 

growth depends on stocking density and survival depends on the size of the stocked 

fish. The growth varies from one water body to another depending on the water 

quality and food availability. 

The management parameters are: 

● Stocking density 

● Size at stocking 

Fishing effort 

Size at capture 

Species management 

Selection of species 

Closed lakes are ideal for practicing culture-based fisheries for the following reasons: 

First, they are very rich in nutrients and fish food organisms, enabling the stocked 

fishes to grow faster to support a fishery. Growth is achieved at a faster rate than in 

reservoirs. Second, the floodplain wetlands allow higher stocking density because of 

better growth performance and high yield. Third, there are no irrigation canals and 

spillways unlike in small reservoirs, which cause stock loss. Also, the lack of effective 

river connection prevents entry of unwanted stock. Stocking of detritivores is allowed 

as the energy transfer takes place through the detritus chain. 

Culture and culture-based systems

There are systems that can combine the norms of culture and culture-based fisheries. 

The marginal areas of the lakes are cordoned off for culture systems either as ponds 

or as pens and the central portion is left for culture-based (or capture) fisheries. 

Floodplain wetlands also can be part of an integrated system. 

Conclusion 

Diagrammatic representation of culture-cum capture 

fisheries Integrated Development of Beloom Beel 

Rivers, estuaries and lagoons, being threatened with environmental degradation, 

are not expected to play a major role in meeting the additional requirements of 

inland fish production. Intensive aquaculture entails high cost and its unchecked 

growth may lead to many new environmental, social and legal issues. Therefore, any 

substantial increases in inland fish production may have to come from the 

development of culture-based fisheries in small reservoirs and lakes. Various kinds of 

enhancements in medium and large reservoirs need to be given priority.

Pen culture in floodplain wetlands 

Culture of fishes and prawns in pen enclosures is a very useful 

option for yield enhancement in floodplain wetlands, 

especially those infested with weeds and harvesting is a 

problem. Pens are barricades erected on the periphery of 

lakes to cordon off a portion of the water body to keep 

captive stock of fish and prawn. They can be constructed in 

any shape and size using a variety of locally available material. 

CIFRI has standardized the methods for culture of freshwater prawn 

(Macrobrachium rosenbergii) in pens. Pens made of bamboo are stocked 

with juvenile prawns at the rate of 40,000/m2 , which are given locally made 

feed with 38% crude protein. The required feeding rate in the pens was very 

low (as low as 1-2% body weight) due to the rich natural fish food resources 

in the lake. The rate varies according to the scale of operation and 

availability of natural food. At the end of a 90-day growth period, prawns 

grew from 4 to 65 g (average) with a survival rate of 60%, resulting in a yield 

of 1,560 kg/ha of pen area. 

These are recognized as eco-friendly and socially relevant means of fishery 

development all over the world. Reservoirs and floodplain wetlands in India can 

make substantial contributions to fish harvests through the adoption of culture-based 

fisheries. 

References 

CIFRI. 2000b. Ecology and Fisheries of Beels In West Bengal Bulletin Central Inland 

Capture Fisheries Research Institute Barrackpore In press 82 pp

Sreenivasan, A. 1984. Influence of Stocking on Fish Production in Reservoirs in 

India. Fishing Chimes. 4: 54-70. 

Sugunan, V. V. 1997. Fisheries Management of Small Water Bodies in Seven 

Countries in Africa, Asia and Latin America. FAO Technical Circular No.933. Food 

and Agriculture Organization of the United Nations, Rome. 

149 pp. 

Sugunan, V. V. and M. Sinha. 2000. Guidelines for Small Reservoir Fisheries 

Management in India. Bulletin No. 93. Central Inland Capture Fisheries Research 

Institute, Barrackpore. pp. 31 

Welcomme, R. L. 1976. Approaches to Resource Evaluation and Management in 

Tropical Inland Waters. Proceedings of the Indo-Pacific Fisheries Council. Food 

and Agriculture Organization of the United Nations. Colombo, October 1976. 500 

pp. 

Prepared by: 

V. V. Sugunan

Community Rice-Fish Farming in Bangladesh 

Rice paddies in the medium and lowland areas are also suitable for fish cultivation. 

In Bangladesh alone, there are more than 1.46 million hectares of lowland rice areas 

that provide scope for fish cultivation. These areas are currently exploited for wild fish 

capture, but productivity is now declining. 

In medium land areas, farmers build dikes about two feet high and fish are grown in 

such rice fields. However, increasing population pressure is resulting in increasing 

fragmentation of land and rice-fish cultivation. These smaller areas are becoming 

less attractive economically. Isolated rice-fish farming poses problems for the 

maintenance of water levels suitable for rice-fish cultivation. 

In addition, dikes are too low to prevent flooding. However, one high dike around a 

number of fields is enough to solve many of these problems. Community fish-farming 

technology provides a strategy for implementing and managing this collective area. 

To overcome the above problems in low and medium land areas, particularly during 

the monsoon season, community fish farming technology has been developed in 

Bangladesh. Since Asia abounds with these low and medium land areas, there is 

opportunity to explore the adaptation of this technique to other areas in the region.

Community rice-fish farming unit in lowland area 

What is community rice-fish farming? 

Community rice-fish farming unit in medium lowland area 

It is a collective effort of people living largely in low and medium level land areas 

undertaking rice-fish cultivation by artificial stocking of fish into the environment. Wild 

fish trapping and cultivation is promoted with cultured fish. There is no limit for the 

number of people involved. In medium land, small groups are generally formed, 

while a bigger group size is common in lowland areas since large areas remain 

flooded and the land is owned by many people. However, from the management 

point of view, if the group is less than 30, community rice-fish farming is more 

effective.

Community fish culture in lowland areas provide opportunities 

as well as challenges to bring together different sectors of 

society. Strategies have to be devised to bring these diverse 

groups of people to work together. Exclusion of any single 

group could pose a threat to long- or even medium-term 

sustainability of the activity. 

The landless form an important group since these people have generally 

been using such areas either for fishing or other activities to derive their 

livelihood. The inclusion of these people to meet the labor requirements of 

the activity like guarding, harvesting, etc. have helped them in getting a 

share of the profit. In some instances, small fish are given to these people to 

sell and make a living. 

One benefit from the inclusion of such people is the elimination of poaching 

and group conflict. Likewise, it increased community bondage. 

Identification of suitable area 

Adequate steps should be taken to identify the suitable area and examine the 

history of the area with regard to drought and flood over time. This will help in 

deciding the level of investment that has to be made, particularly with regard to 

raising dikes, construction of bana (bamboo net), etc. This is particularly important in 

low-lying areas, where heavy floods are more common. Suitable low and medium 

ricefields are those which are surrounded by elevated areas like roads, homesteads, 

and where it is easy to install inlets and outlets. 

Formation of groups 

Although the landless 

have no land in the 

cultivation unit, they 

share equal 

contributions with the 

other members of the 

group. Their involvement 

in the group provides 

them priority in selling 

their labor whenever 

necessary. 

Organizational 

framework 

The early development of an organizational framework helps to maintain group cohesiveness and to 

avoid conflicts. The framework should be developed with the participation of all the stakeholders and

should cover a range of issues and aspects. 

Tips for developing an organizational framework 

Ensure group cohesiveness and resolve 

conflicts. Encourage farmers to elect a leader of 

their choice. 

Increase the facilitation skills and leadership 

qualities, provide special training to the elected 

leader/s. 

Assist the group to develop their rules and 

regulations for the group activity, which should 

include sharing of costs, risks and benefits. 

Help the group to develop their own financial 

management system. 

Resource management aspects 

The organizational framework should help in the efficient management of the 

resources to get the best output. The following are some key points to be considered 

in resource management: 

● The building of dikes to protect the area from floods is a major activity and 

should be done early in the season. 

● Wild fish constitute a good source of income in low-lying areas. Special nets 

can allow wild fish to enter (but not return) and help to increase yields.

● Focus learning sessions on the 

symbiotic relationship 

between different species 

living in the aquatic 

environment. 

● Encourage farmers to 

efficiently use peripheral dikes 

for vegetable cultivation. 

● Learning sessions focused on 

the integrated pest 

management (IPM) 

approaches with emphasis on 

the natural management of insect pests would be helpful to ensure that 

people will not resort to pesticide use. 

● It is necessary to guard the resources from theft, poisoning, etc. 

● Feeding and fertilization are generally avoided to reduce costs and risks, 

particularly in the formative years. 

● Help farmers to understand the principles of the activity and encourage them 

to develop technologies appropriate to the local environment. 

● Use participatory monitoring and evaluation tools to ensure community 

participation in the management of the activity. 

IPM is the economical, ecological, environmental and social strategy that 

focuses on long-term prevention of pest problems. This is done through a 

combination of techniques such as encouraging biological control of pests 

and ecologically sound agricultural practices. 

Training course for group organizers 

Group organizers are provided with training to help them organize the groups better. 

The training is composed of four modules. 

Module 1 

Module 2 

Objectives 

Build better understanding on resource management. 

Increase leadership qualities of the elected leaders. 

Strengthen organizing skills of group leaders. 

Build understanding on resource management. 

What is community rice-fish culture, why is it required – costs and 

benefits, opportunities and constraints for community rice-fish.

Module 3 

Module 4 

Role of group organizers, organizing groups, solving conflicts in groups 

and team building. 

Organization, meeting, agenda setting, facilitation and documentation 

of meetings. 

Participatory decision making process, role of members in guarding, 

marketing and harvesting, accounts maintenance and planning for the 

coming season. 

Problems encountered 

● Internal group conflict 

affects group integrity 

● Weak leadership of the 

group organizers 

● Lack of interest of the 

participants in the early 

stage of the process 

● Less coordination among 

the group members 

● Lack of proper size 

fingerlings 

● Less access to fish market to 

sell the fishes 

● Jealousy among members 

of the community 

● Poisoning 

● Poaching 


● Unity among the group is a key to success. Conflicts, if any should be resolved 

early through community participation. 

● Community approach is a good tool to promote IPM and eliminate pesticide 

usage. 

● The productivity of the community fish culture units is generally high as 

compared to general rice-fish system owing to better growth of fish and

contribution from wild fish. 

● Avoid overstocking of fish to manage disease in winter and promote good 

growth of fish. 

● If there are rice plots in the area, avoid stocking grass carp. 

● Development of fish seed bank will be helpful to overcome the problem 

related to scarcity of fingerling. 

Conclusion 

Community fish culture provides an opportunity for better use of resources, which at 

present is not exploited. Due to lack of leadership and direction, these resources are 

often either unused or become the subject of conflict. Hence, facilitation by 

outsiders to help the community in realizing the potential would help in better use of 

the resources. 

Community rice-fish farming in Jamalpur, Bangladesh 

Farmers, in low-lying areas of Bewra Plash Tala of Jamalpur 

District of Bangladesh, decided to experiment on community 

fish culture activity. 54 farmers of the village joined together 

using a total area of about 8 ha. While there were some 

farmers who were the members of farmer field school, majority 

of them were non-members. The group elected a group leader 

for the management of the activities. The chairperson and the 

secretary were given training on group organization skills in a special training 

conducted by New Options for Pest Management (NOPEST) project of 

CARE. 

26,000 fingerlings of different fish species (rohu, mrigal, catla, carpio and 

silver barb) were stocked in the area. These were grown with natural food 

available in the fields.To meet expenses incurred, each member contributed 

200 Taka (54 Taka = US$1). 

To counteract flash floods resulting from heavy rains, the group members 

made bana (nets) using available resources. These stretched over 600 m. In 

addition, the fish are also protected by placing banana trees, nets, tree 

branches, etc. 

Even with the loss of some fish during floods, the community was still able to 

harvest 2.2 tons of fish during the six months culture period. The earnings 

reached a total of 66,000 Taka and each member got a share of 1,222 Taka. 

The group is now in its third year of operation and functioning on its own. 

With the success of the group, several communities in the area have 

initiated similar activities in other project areas of CARE. The community fish 

culture activity has helped bring large areas under rice-fish cultivation.The 

impact of the activity is seen in: 

increased community cooperation; 

better use of the resources; 

increased fish availability in the area; and 

increased income.

Prepared by: 

A. K. M. Reshad Alam, M. C. Nandeesha and Debasish Saha

Marine Reserves and the Role of Local 

Government Units in the Philippines 

Overfishing, destruction of marine habitats and the resulting decline in fish catches 

affect small-scale fishermen throughout the Philippines. The establishment of marine 

protected areas is a recognized and proven strategy for resource conservation and 

management. The protection and management of marine areas can result in 

marked increases in fish growth and yields. Marine reserves protect breeding 

populations of corals, mollusks, fishes, shrimps, mangroves and seagrass from which 

neighboring depleted areas can be recolonized. Local government units (LGUs) 

play a critical role in establishing and managing marine reserves and protected 

areas. 

What is a marine reserve?

A marine reserve is an 

area within a coastal 

zone where resource 

extraction is either 

banned or highly 

regulated. It may be a 

part of a single or a 

combination of any of 

the major coastal 

ecosystems (coral reefs, 

mangroves, seagrasses, 

soft-bottom 

communities). Resource 

utilization in these areas 

is strictly managed, 

hence, resources are 

protected. 

Also, marine reserves 

conserve biodiversity to 

support local fisheries. 

They are venues for 

education, research, 

and habitat restoration. 

These areas provide an 

environment for low- 

impact aquaculture managed and organized by coastal communities. 

Resources in marine reserves may be viewed as "common property" for the exclusive 

use by a community. Various sectors of the community therefore "own" or have an 

interest in the use, management, and protection of marine reserves. 

Stakeholders

Legislative and legal support 

The protection and allocation of marine and inland aquatic resources is enshrined in 

the laws of different states. In the Philippines, this is amply stated in the 1987 

Philippine Constitution, which gives preference to subsistence fisherfolk. 

Stakeholders 

Fisherfolk who depend on the sea for their livelihood and benefit from the 

improved fishery as a consequence of establishing a marine reserve. 

Researchers who conduct studies to monitor the status of 

resources in marine reserves as an input to management 

decisions. 

Non-government organizations (NGOs) guide collective action 

and advocacy among resource-users. 

Local government units (LGUs) provide the institutional 

framework and legal basis for any individual or collective 

management actions. 

Being direct-users, fisherfolk are day-to-day managers in the use of marine resources. 

This requires collaboration with LGUs, which provide the enabling legislation to make 

protective management actions binding to all stakeholders.

Key legislations in recent years have empowered and given both the LGUs and 

fisherfolk greater control over their resources in municipal waters. 

Co-management of 

marine reserves 

Enabling national legislation 

allowed the evolution of comanagement 

schemes involving 

the participation of all stakeholders 

in the decision-making process, 

which is a requirement to sustain 

management intervention 

strategies such as marine reserves. 

Administered by the LGU, the 

Fisheries and Aquatic Resource 

Management Council (FARMC) is 

a multi-sectoral body of fishers’ organizations, NGOs, the LGU and government 

agencies that regulate resource use by all stakeholders. FARMCs provide a 

legitimate forum to raise fishery-related issues and problems. The LGU and the fishers’ 

organization, often assisted by an NGO, national agencies and a federation of 

fishers’ organizations, conduct general assemblies and consensus-building activities 

to draw up solutions suitable to the community. The LGU enacts fishery-related laws 

and policies recommended by the FARMC, thus, minimizing conflicts in resource use. 

The municipal and barangay (villages) councils and deputized fisher-wardens 

enforce the regulations and monitor compliance. 

Caution 

Marine reserves have proliferated in many coastal municipalities in the 

Philippines and elsewhere as a result, in part, of the global conservation 

movement in recent years. Indeed, this has been a welcome and innovative 

move, especially in coastal communities where overfishing has been 

rampant. However, in the rush to adopt a novel strategy, the basic norms of 

establishing and managing marine reserves have been overlooked, resulting 

in the non-sustainability of management measures. Physico-biological 

factors and, most importantly, sociopolitical considerations are often 

ignored. Marine reserves can be an effective resource management tool 

when concerns of all stakeholders have been and will be considered. Sadly, 

many marine reserves in the country are "paper" reserves, with no credible 

conservation measures being applied. 

LGU support of marine reserves: Two examples

1. Malalison Island, Culasi, Antique 

The island community of more than 100 households consists of subsistence fishers, 

having monthly incomes below the national poverty level. Before 1990, the island’s 

reef fishery was typically open-access, with island and other fishers from neighboring 

coastal barangays engaged in illegal and destructive fishing. Conflicting national 

fishery laws encouraged the encroachment of commercial fisheries in municipal 

waters (including the island), which became a source of dispute. Coastal resource 

conservation among island fishers was practically non-existent. 

This scenario changed in 1990. An exclusive fishery-use zone of one square kilometer 

was initially set by a Culasi municipal ordinance. This was followed by another 

ordinance in 1991, which permitted the deployment of artificial concrete habitats in 

the protected zone. Organized fisherfolk succeeded in getting the Culasi municipal 

council to declare the entire waters of Malalison Island for the island fishers’ exclusive 

use. A ban on commercial fishing and destructive gears was imposed. In 1995, 

acting again on the petition of the organized fisherfolk and the barangay FARMC, 

the Culasi municipal council declared one of the island’s reef fishing grounds a 

marine sanctuary closed to any form of fishing. No serious violation of the sanctuary 

has yet occurred. To date, resource monitoring of the island’s marine resources by 

the organized fisherfolk, together with SEAFDEC researchers, provides advice on 

management decisions. Since co-management arrangements have been in place, 

performance indicators (equity, efficiency and sustainability) have improved, 

particularly in the perceived control over fishery resources, fair allocation of access 

rights, and participation and influence in fishery management. 

Related Philippine Laws 

The Local Government Code of 1991 (Republic Act 7160) provides 

LGUs greater and exclusive access to their coastal resources. LGUs are 

authorized to issue licences for and collect fees from several fishery 

activities in municipal waters without prior approval from the national 

government. Municipal waters extend 15 km from the shoreline. The 

Code does not explicitly stipulate the establishment nor governance of 

marine protected areas in municipal waters. 

The Fisheries Code of 1998 (Republic Act 8550) allows LGUs and 

municipal Fishery and Aquatic Resource Management Councils 

(FARMCs) to recommend to the national government the declaration of 

closed seasons for the fishery and the establishment of at least 15% of the 

total coastal area in municipalities as fishery reserves and sanctuaries. 

Local representation is emphasized in municipal FARMCs. Together with 

barangay (village) FARMCs created in 1995 by Executive Order 240, 

municipal FARMCs may recommend the enactment of relevant fishery 

legislations to the municipal council. 

The National Integrated Protected Areas System (NIPAS) Act of 1992

(Republic Act 7586) provides the legal mechanism for the establishment 

and management of protected areas to be directly managed by a 

Protected Area Management Board (PAMB). With assistance from the 

Department of Environment and Natural Resources (DENR), presidential 

decrees then national legislation set aside protected areas. Like the 

FARMC, local representation is strong in the PAMB. The board implements 

a general management strategy or plan, which is formulated in 

consultation with both national and local stakeholders. 

2. Sablayan, Mindoro Occidental 

Exploited by local municipal fishers and by commercial fishers from elsewhere, the 

reefs of Sablayan have become sources of conflicts among contending users, 

including sports diving enthusiasts who frequented Apo reef. In 1980, the national 

tourism agency declared Apo reef a marine park and in 1983, through a municipal 

ordinance, a tourist zone and marine reserve. Over the years, however, enforcement 

of protective management has failed to the detriment of reef resources, since local 

stakeholders were not fully consulted. Local fishers resisted the plan to protect Apo 

and neighboring reefs in the municipality. Clearly, the approach of establishing a 

marine reserve in the area had to change. With the assistance of university 

researchers, an NGO, and LGU extension workers, public consultations and 

dialogues were initiated with local fishers until, in 1995, Apo reef was declared a 

"natural park" under the NIPAS Act. Nearby reefs became municipal marine reserves. 

Municipal fishers were organized into a cooperative. Other livelihood options were 

extended to members of the cooperative to mitigate the impact of regulating 

fishing in their reefs. The LGU deputized fisher-wardens or Bantay Dagat to patrol Apo 

and neighboring reefs to ward off poachers. Fishery co-management of the marine 

reserves has continued to date. All stakeholders are being educated on the value of 

conservation of their coastal resources. Good rapport exists between fishers and the 

LGU. Fishers have reported an improvement in their daily catch from outside the 

marine reserves. In addition, several fish, sea turtles, and migratory birds have 

returned to the area. 


● Consultations and dialogue among stakeholders are essential in ensuring the 

sustainability of marine reserve management. 

● Empowered and enlightened fisherfolk can effectively take part in the 

management and use of marine reserves. 

● Research-based information is important in arriving at decisions and in 

formulating policies. 

● Management of marine reserves can be sustained by instituting an 

acceptable cost-sharing scheme which confers on the local fishing 

community some equity rights. This motivates them to continuously support the

project. 

References 

Agbayani, R.F., D. B. Baticados and S. V. Siar. 2000. Community Fishery Resources 

Management on Malalison Island, Philippines: R & D framework, interventions and 

policy implications. Coastal Management, 28: 19-27 

Baticados, D. B. and R. F. Agbayani. 2000. Co-management in Marine Fisheries in 

Malalison Island, Central Philippines. International Journal of Sustainable 

Development and World Ecology, 7: 1-13 

Roberts, C. M. and N. V. C. Polunin. 1991. Are Marine Reserves Effective in 

Management of Reef Fisheries? Reviews in fish biology and fisheries, 1: 65-91. 

Siar, S. V., R. F. Agbayani and J. B. Valera. 1992. Acceptability of Territorial-use 

Rights in Fisheries: Towards Community-based Management of Small-scale 

Fisheries in the Philippines. Fisheries Research, 14: 295-304. 

Prepared by: 

Luis Ma. B. Garcia and Fernando Dalangin

Local Knowledge and the Conservation and Use 

of Aquatic Biodiversity 

It was only recently that people in international development circles began to 

recognize the importance of biodiversity for rural livelihoods. Traditional rural 

societies have long understood the importance of biodiversity and have, either 

intentionally or incidentally, developed practices to protect it. This is because rural 

people, with varied livelihood strategies, rely heavily on biodiversity for their 

livelihoods. For example, in Khong District, Champasak Province, in Southern Laos, 

local people living on islands in the middle of the Mekong River use different 

traditional and modern fishing methods to harvest about 200 fish species at different 

times of the year, of which approximately 150 are significant in terms of maintaining 

their livelihoods. The reliance of local people on biodiversity has provided them with 

a powerful incentive to ensure that it is maintained.

Local knowledge (LK) is the knowledge that people in a given community 

have developed over time and continue to develop. LK is dynamic and is 

based on the experiences of the holders of the knowledge. LK is sometimes 

referred to as indigenous knowledge (IIRR, 1996), or local 

indigenous knowledge. Many terms with similar meanings are 

used. 

Biodiversity can be described as the variety of living organisms 

and is often considered at three levels: genetic, species and 

ecosystem (Koziell, 1998). 

Rural traditional biodiversity conservation 

Often, biodiversity conservation 

occurred coincidentally through 

cultural beliefs and taboos, leading to 

practices that are essentially but not 

entirely biodiversity friendly. However, 

beliefs have sometimes been 

established by traditional societies to 

support practical concerns, including 

those related to natural resource 

management and biodiversity 

conservation. Nevertheless, it must also 

be understood that organized attempts 

to protect biodiversity in rural areas 

arise as a direct or indirect reaction to 

natural resource management and 

livelihood crisis. In many cases the most 

biodiversity friendly societies are 

notable not for their intricate 

conservation oriented regulations, but 

rather for the lack of them. Therefore, 

there is a risk that outside influences might break down these traditional systems and 

local people may be unable to adapt, thus resulting in the community adopting 

new livelihood strategies that may not be ecologically sustainable or biodiversity 

friendly.

Rural people engaged in subsistence-oriented livelihoods are notable for 

their practical way of viewing the world. However, it would be incorrect to 

suggest that they care only about basic subsistence and improving their 

material wealth. For example, in Khong district local people 

often state that they want to see particular fish species and 

other aquatic organisms protected because they do not want 

their children and grandchildren to grow up not knowing what 

those species look like. When people have a long history of 

living in a particular area, their sense of history and belonging, 

aside from very practical reasons, often act as powerful 

incentives for protecting biodiversity. 

Local people living in Khong District along the banks or on islands in the middle of 

the Mekong River rely heavily on the aquatic resources found near their 

communities. This heavy reliance on aquatic resources has resulted in the 

generation of LK regarding the management of resources that communities depend 

on. For example, their LK led them to conclude that deep-water pools in the middle 

of the Mekong River play a critical role in maintaining aquatic communities. They 

recognize that during the low water dry season, deep-water pools act as critical 

refuges for fish, including broodstock. Some governments in the Mekong Basin have 

adopted regulations designed to conserve fish species during their spawning season, 

which for most Mekong River fish species is during the wet season. LK suggests, 

however, that protecting fish during the dry season may be more important, since 

traditionally that is the time of greatest impact on Mekong fish through harvesting, as 

water levels are low, and the rice season is over, giving local people more time for 

fishing. 

"Sea cucumbers are very important. They clean sea grasses. If your house is 

in a mess you do not like to live there and you move to another place. Fish 

are just like people." A fisher from Rizal, Misamis Occidental Province, 

Philippines states. 

Fishers’ local knowledge is used to promote the conservation of the sea 

cucumbers and other sea grass bed species, which are important parts of 

the aquatic ecosystem. 

In the past, people in Khong District protected deep-water pools in the Mekong 

River through taboos based on a fear of dangerous spirits that were believed to 

inhabit the areas. Moreover, there was little need for locals to fish deep-water areas, 

since fish were plentiful throughout the river, including shallow areas. 

The role of local knowledge in the monitoring and protection of 

aquatic biodiversity in a modern world

With the relatively recent but rapid arrival of the market economy in Laos, the desire 

for material wealth has increased rapidly, as has been the case in many subsistenceoriented 

societies in various countries in Asia. Efficient fishing gears, such as nylon gill 

nets, have also been introduced, making it much easier for locals to exploit fisheries 

resources. New markets have, for the first time, given fish a value beyond simply food 

for the family. These changes led to the weakening of many of the traditional taboos 

and norms that once kept locals from fishing in deep-water pools in the Mekong 

River in Khong District, Southern Laos. When locals first began fishing the deep-water 

pools in the Mekong River over 20 years ago, fish were plentiful. Later, there has 

been a noticeable decline in fish catches due to overexploitation. 

Local protection of aquatic biodiversity can be observed in many 

communities adjacent to limestone mountains in Khammouane Province, 

Central Laos. During the rainy season lowland areas are flooded. However, 

during the dry season most streams and natural small water bodies dry up. 

The fish are forced to seek refuge in the few places that retain 

enough water to sustain them, including caves situated at the 

base of the mountains. The fish that survive in these caves act 

as important broodstock. At the beginning of the rainy season, 

when the caves overflow, the fish re-enter streams and 

wetlands in surrounding areas to spawn, leading to high 

fisheries production in surrounding areas. While the 

conservation value of protecting these areas is generally recognized by 

local people due to their extensive LK, this conservation effort is not directly 

associated with this understanding. The impetus for conservation is the 

locals’ fear of spirits that they believe protect the caves. For them, the spirits 

represent a powerful tool for protecting important aquatic resources to this 

day. 

The LCFDPP (The Lao Community Fisheries and Dolphin Protection Project), 

established in 1993, contacted the local fishers who had witnessed these changes in 

fish stocks. The fishers were quick to utilize their LK to identify the deep-water pools 

that were potentially important keystone habitats. They also used their LK regarding 

fish ecology to indicate that it would be wise to protect the deep-water pools as Fish 

Conservation Zones (FCZs), or fishery "no-take zones". With the fear of "spirits" no 

longer enough to protect deep-water areas, the fishers recognized the need to 

implement a new system that would effectively lead to the protection of key deepwater 

pool habitat in the context of Government supported community-based comanagement. 

Since then, a network of 68 mainstream Mekong River FCZs have 

been established in 63 villages in Khong District, and the number continues to grow. 

Keystone habitats are critical habitats that are proportionally more 

important than others and are essential for the maintenance of ecological 

systems. 

Monitoring the impact of fish conservation zones (FCZ)

The extensive LK of local people 

in Khong indicated to them that 

deep-water pools do not 

constitute a single habitat type. 

Every area was ecologically 

unique and every deep-water 

pool supports a unique 

assemblage of aquatic animals. Thus, the monitoring of FCZs requires a variety of 

methods that takes biodiversity into account and local understanding of the areas. 

In Central Bangladesh, professional inland fishers release back into the wild, 

after capture with seine nets, the biggest fish. Their LK helps ensure that fish 

will be available during the next fishing season. 

Local fishers in Khong have utilized and built on LK by developing unique methods 

for monitoring the success of FCZs that they have established in the mainstream 

Mekong River. Ban Tholathi, a village on a small island in the middle of the Mekong 

River near the border with Cambodia, is unique in that the large freshwater 

Smallscale croaker Boesemania microlepis (pa kouang in Lao) is known to be 

abundant in the area. Villagers have detailed LK regarding the biology and ecology 

of this and many other species, but are particularly interested in the Smallscale 

croaker, since the carnivorous species is high valued and a good tasting food fish 

that reaches at least 18 kg in weight. Moreover, this species is unique because of its 

habit of emitting loud and easily audible vocalizations during the height of the dry 

season, between March and May, its spawning season. LK also recognizes that the 

species only inhabits specific deep-water habitat over 20 m deep and with counter 

eddies in the dry season. 

Along the Mekong River in Vietnam, Cambodia and Laos, local people 

have taboos that prevent them from harming or eating Irrawaddy dolphin 

(Orcaella breviorstris) meat. They believe that it is bad luck to kill dolphins 

and that dolphins can protect fishers from dangerous sting rays and 

crocodiles, or from drowning. In coastal areas of Southern Vietnam, fishers 

also culturally protect dolphins and whales, and erect small shrines where 

they deposit the bones of dead marine mammals. Since whales and 

dolphins have very low reproductive potentials, these taboos and beliefs 

have traditionally been important in protecting dolphins, which are now in 

serious decline due to various unintentional human-caused impacts, such as 

entanglement in gill nets. 

Some 20 years ago, the Smallscale croaker was common around Ban Tholathi. 

During the dry season, its "croaking" was so loud that locals were afraid to paddle 

their canoes past the area where the croakers were concentrated. However, the 

introduction of nylon large-meshed gillnets and the deterioration of local taboos that 

prevented villagers from fishing the deep-water pools resulted in intensive harvesting

of the croaker. Within just a few years, the villagers noticed that the vocalizations 

had become faint and almost disappeared altogether. This indicated that stocks 

had been heavily overexploited. 

Since protecting the area as an FCZ, locals have qualitatively monitored the 

Smallscale croaker population by listening to their vocalizations. Fishers were pleased 

to find that the vocalizations increased little by little over the years. Now, five years 

after the establishment of the FCZ, they believe that the level of vocalizations has 

returned to what it was prior to the beginning of gill net fishing in the area. In 

addition, they reported that Smallscale croaker populations have expanded to 

areas outside the FCZ, since fishers have both heard and caught them in surrounding 

areas. Other indicators include: 

l The monitoring of rocks in the water close to the edge of relatively fast flowing 

areas. Fishers recognize that many of the most important fish species in their FCZs are 

herbivorous algae grazers. By observing rocks in shallow water at the edge of their 

FCZs, they get a feel for how many fish are in the area. If the rocks are relatively 

clean of algae, grazing is heavy, and fish are assumed to be plentiful. Moreover, 

different species have different mouth shapes and sizes, and fishers can recognize 

the grazing "tracks" that different species of fish make on rocks. 

l The monitoring of the surfacing of different species of fish in FCZs. While scientists 

know virtually nothing about fish surfacing in the wild, villagers recognize that 

different species surface in different ways, and at different times of the day. They 

utilize this knowledge to determine what species are found in FCZs, and to estimate 

their numbers.

l The monitoring of levels of fish catches in areas adjacent to FCZs can provide an 

important indication of success 

Villages in Khong with FCZs have been encouraged to establish villagebased 

participatory monitoring programs with village fishers as researchers. 

Locals are initially asked to hypothesize about what fish species have 

benefited from FCZs. They then set the research agenda by determining 

how best to test their hypotheses. For example, increased catches of 

particular fish species in areas adjacent to FCZs are an important indicator 

of success. Villagers then decide what fishing methods should be monitored, 

and at what time of the year. They then choose the fishers in the village most 

suited to conduct the research, and are interested in doing so. Local 

researchers are trained in basic data collection methods. The research then 

begins, with researchers documenting their daily fish catches using 

notebooks and pens. The collection of data on a daily basis over months 

helps stimulate fishers to think about what is happening. Frequent meetings 

among the researchers and other community members are 

organized to review the research. Later the data are compiled 

and analyzed by the community and NGO. The villagers then 

consider the implications of the results and how they can 

contribute to improving the management of FCZs. This process 

helps build up LK, and also provides a certain level of 

quantitative data that may be useful for the government and 

development agencies, and which can be compared with data collected 

in the future. 

The role of indigenous knowledge with respect to local ecology 

Local communities have a broad and holistic understanding of the linkage between natural resources. 

Understanding the linkages between different resources and habitats helps them appreciate the value 

of biodiversity, and the value of species and habitats that might not appear to be important if viewed 

from a narrower perspective. For example, fishers in Khong identified over 70 plant species that they 

believe fish are utilizing. Villagers also use a number of wild fruits, leaves and even flowers as baits 

for targeting particular species of fish. 

Caution! 

LK is not always useful and can sometimes lead to the transfer 

of incorrect information. The community-based development 

of LK can help solve this problem. It should also be understood 

that LK is easily misunderstood and misinterpreted by outsiders. 

People in Khong District do not see FCZs as isolated entities, but rather as a part of larger systems, 

albeit an important one. They consider FCZs to be only part of what is needed to ensure the

maintenance of biodiversity. Their LK indicates to them that many strategies, including measures 

related to habitat protection, will be necessary to effectively protect aquatic biodiversity. While there 

is no room here to elaborate on all the measures locals have adopted as part of their co-management 

systems, it is useful to provide one example of the linkages that locals have made. 

Traditionally, farmers in Bangladesh involved in wild fish trapping systems in 

rivers, canals, rice fields, etc. use branches of the "shewra" tree to attract fish 

into an area. This practice has two purposes, which are based on farmer LK. 

Fish are attracted to the branches because the bark quickly 

decomposes in the water, helping provide food for many fish species. 

Moreover, periphyton grows quickly on the branches, and serves as food 

for fish. 

Tree branches placed in ditches act as anti-poaching devices, and 

as refuges for fish, until harvesting occurs. 

Some Mekong river fish species migrate from deep-water areas, where they stay in the dry season, to 

streams, natural depressions and inundated rice fields, which they inhabit during the wet season. 

Many communities have developed specific co-management regulations designed to protect fish as 

they move from the mainstream Mekong River to these habitats. For example, villagers often prohibit 

trap fishing in streams during the beginning of the rainy season in May and June, when fish migrate 

upstream. This gives the fish a chance to migrate into wetlands unobstructed, so they can spawn. 

However, at the end of the rainy season, after juveniles have had a number of months to grow, locals 

allow trap fishing in the streams as the fish attempt to return from the drying out wetlands to the 

mainstream Mekong River. LK has, in this way, been utilized to ensure that indigenous fish stocks are 

protected, and that maximum benefit from the resource is gained. 

Supporting LK at the community level 

The LK in Khong has helped determine what strategies are likely to be the most 

successful in protecting aquatic biodiversity. However, LK only remains relevant 

when it is dynamic (i.e., local people are constantly building on LK through direct 

experiences). Development agencies, including NGOs, can help promote LK in 

communities. The LCFDPP has tried to promote LK, not only by recognizing its 

importance, and promoting it within the local Government, but also by providing 

relevant information to local people. Even more critically, the LCFDPP has 

encouraged locals to be observant, learn from real experiences, and communicate 

those experiences to groups so everyone can learn.

It is important to recognize that the network of FCZs and other comanagement 

regulations support and reinforce each other, since fish do 

not recognize village boundaries. The more villages establish comanagement 

regulations, the greater the chances that individual 

communities’ regulations will be successful, especially in terms of migratory 

species. Local people are aware of this, and are therefore keen to see the 

system expand throughout the Mekong Basin. 

Points to consider in developing LK in rural communities 

● Extensionists must believe that farmers and fishers can be experts. Rural people 

often have keen interpersonal relation senses, and quickly recognize whether 

outsiders really believe that LK is relevant and can be developed. If 

extensionists are not sincere, locals are unlikely to take efforts by outsiders 

seriously. 

● Do not be overly prescriptive. Learn from local people. Good extension begins 

with learning from people, not from trying to teach them. If outsiders can put 

extension ideas into the context of LK, local people are much more likely to 

take them seriously. 

● Develop methods in which locals can actually see, feel or hear what is going 

on within aquatic ecosystems. Rural people are practical, and are unlikely to 

adopt practices that are unproven or cannot be easily understood and 

justified in the context of past experiences. 

Hilsa (Tenualosa ilisha) is the most relished fish in the State of West Bengal in 

India. It is an anadromous fish that migrates up the Hooghly River for 

breeding. A local custom in West Bengal prevents the eating of the fish from 

July to mid-September. After that, on the occasion of Durga Puja, the fish is 

ceremoniously brought home to mark the beginning of the consumption 

season. The season of taboo coincides with the upriver migration and 

breeding season of the fish. By delaying consumption of hilsa, it is ensured 

that the fish completes breeding before it is caught. This is a covert 

conservation measure developed through LK about the fish’s breeding 

behavior. 

Anadromous species are 

those that spend much of their 

lives in salt water 

environments, but migrate into 

freshwaters for spawning 

purposes.

● Provide opportunities for locals to see the linkages between practices and results. This can be 

done by encouraging locals to participate directly in monitoring and evaluation activities. Let 

locals determine the agenda and the methods to be used. Encourage them to test hypotheses 

that they have developed, and provide opportunities for locals to analyze the results in research 

groups, encouraging them to communicate the results with each other. LK can act as a 

powerful peer review tool. 

● Help disseminate information about management practices developed by locals and that can be 

justified in the context of LK. Certain members of communities inevitably possess more LK 

than others, and therefore can more easily conceptualize ways of solving problems. 

Extensionists can provide opportunities for locals to exchange information, either within 

villages or between them. Locals are more likely to accept ideas of other locals, since their 

references and experiences are similar. 

● Make learning about ecosystems fundamental, as a good understanding of ecosystems will 

provide a strong basis for improving management over the long run. 

● Encourage locals to be innovative, adaptive and flexible. Create conditions where locals do not 

feel that it is risky to try out new things, because they can always abandon or alter practices 

that do not work out as expected or hoped. It is important to recognize when doing extension 

that rural people are generally adverse to risk. 

● Make the development of LK need-based. If locals do not see how developing a particular 

aspect of LK will benefit them in a practical way, they are unlikely to make much effort to 

learn. 

● Work with children. Create opportunities for children to learn from elders. Children are the 

future. Moreover, their actions and ideas can have a profound effect on their parents, relatives 

and peers. Questions posed to elders by children can help adults make linkages that contribute 

to the development of their own LK. 

Conclusion

It is commonly believed in 

international development circles 

that people living in relatively 

subsistence societies, often referred 

to as the "poor", have little interest in 

environmental conservation and 

sustainable resource management. 

Moreover, many believe that poor 

people are not likely to take 

environmental protection seriously 

until they have gained a significant 

amount of material wealth. 

Unfortunately, this view extends to 

many urban people, and 

government officials. It is true a 

certain minimum level of food, 

shelter, clothing and medicine is 

required before people can 

consider finding alternative ways to 

survive and that poor people often 

do cause environmental damage to 

make a living. It is incorrect, 

however, to assume that people in 

rural areas generally do not hold a 

significant amount of LK about the 

environment and that they do not 

care about biodiversity. On the contrary, they rely on nature to such an extent that it 

is only logical that they care about its maintenance. We must recognize that 

biodiversity is important for local people, especially the poor, and that LK has a role 

to play in protecting it. 

References 

IIRR. 1996. Recording and Using Indigenous Knowledge: A Manual. International 

Institute of Rural Reconstruction, Silang, Cavite, Philippines. 

Koziell, I. 1998. Biodiversity and Sustainable Rural Livelihoods. Pages 83-92 In D. 

Carney (ed.), Sustainable Rural Livelihoods: What contribution can we make? 

Department for Internation Development, London. 

Prepared by: 

Ian G. Baird and Julia Lynne Overton


Freshwater 

systems/Terrestrial systems 

An Overview of Rice-Based 


Rice-Based Aquaculture in 

China 

Enhancing the Performance of 

Irrigation Systems through 

Aquaculture 

Rice and Fish Culture in 

Seasonally Flooded 

Ecosystems 

Increasing Wild Fish Harvests 

by Enhancing the Rice Field 

Habitats 

Polyculture Systems: 

Principles and Basic 

Considerations 

Promoting Rice-Based 

Aquaculture in Mountainous 

Areas of Vietnam 

Aquaculture in Stream-Fed 

Flow-Through Ponds 

Short-Cycle Aquaculture in 

Seasonal Ponds 

Low-Cost Aquaculture in 

Undrainable Homestead 

Ponds 

Homestead Fish Culture: An 

Example from Bangladesh 

Integrating Intensive and 

Semi-Intensive Culture 

Systems to Utilize Feeding 

Waste 

Low-Cost Fertilization in 

Inland Pond Aquaculture 

Culture of Fish Food 

Organisms and Biofertilizers 

Feeds in Small-Scale 

Aquaculture 

Decentralized Seed 

Production Strategy for the 

Development of Small-Scale 

Aquaculture 

Small-Scale Eel Culture: Its 

Relevance for Rural 

Households 

Small-scale Macrobrachium 

Culture in Bangladesh 

Culture of Chinese Mitten- 

Handed Crabs 

Aquaculture and Sewage 

Water Treatment 

Water Quality Management 

for Freshwater Fish Culture 

Freshwater systems/Terrestrial Systems

An Overview of Rice-Based Small-Scale 

Aquaculture 

Asian countries as rice-fish societies 

Many countries in Asia can be called "rice-fish societies" 

in the sense that rice is the staple crop for basic 

subsistence, while fish is the main source of animal 

protein. The availability of rice and fish has long been 

associated with prosperity and food security. In Thailand, 

for example, the early inscription of the 13th century 

king, Ramkhamhaeng, states "in the waters are fish and 

in the field is rice" as an indicator of wealth and stability. 

In Vietnam, there is also a traditional saying that rice and 

fish are like mother and children. 

The cultivation of most rice crops in irrigated, rainfed 

and deepwater systems offers a suitable environment for 

fish and other aquatic organisms. Traditionally a good 

deal of the fish for household consumption was caught 

from the paddy fields. With the conversion of wetlands 

into agricultural land and the intensification of rice production, this fishery has 

declined and farmers have turned to aquaculture as an alternative source of animal 

protein. It has to be recognized that such pressures have been uneven and there are 

still considerable areas of flood plain in the region where the fishery still offers an

adequate living to the local population. 

In Cambodia, studies conducted by the Asian Institute of Technology (AIT) 

Aqua Outreach Program with the Department of Fisheries suggest that 

virtually all rice-farming households in the province of Svay Rieng, on the 

periphery of the Mekong flood plain, regularly collect substantial quantities of 

fish and other aquatic produce from their fields. A study in three communities 

in the district of Svay Theap showed an average per capita consumption of 

wild fish caught from ricefields and adjacent swamps of 25 kg. Each family 

member consumed 21 kg of other aquatic animals during the same period. 

During this period, virtually no fish or other aquatic products were purchased. 

The amounts caught vary according to the total amount and distribution of 

rainfall, with good rainfall early in the year increasing the catch. 

The nature of this fishery varies with the season and the proximity of river systems. In 

Cambodia, in the wet season, the main fishery is in the rice field itself, as the fish 

move out of the main spawning grounds. The rice field fishery at this time is largely 

open access, signifying the relative abundance of the fish. The same is true for the 

cool season as the fish migrate back to the refuges. In the early part of the hot 

season, some farmers catch fish in deep trap ponds, some of them originally dug for 

fish culture by well-meaning projects. Some of the bigger trap ponds secure as much 

as 300 kgs of high value black fish, such as snakehead Channa striata (25-40% of the 

catch) or Clarias catfish (35-40%). These air-breathing species are well adapted to 

the swamp-like conditions of rice fields with fluctuating water levels and are highly 

appreciated wild fish in the capture system. They are carnivorous and will feed on 

other introduced fish but can be sold for twice the price of the equivalent cultured 

fish at local markets, as in Thailand. In Cambodia, they are also sold at high prices, 

leading Gregory and Guttman to claim that farmers in the areas are poor in all but 

fish. Clearly in such contexts, fish culture is unnecessary, although there are quite 

marked variations in the productivity of the fishery over rather short distances. 

Rice-based aquaculture systems: Rice-fish culture or pond culture? 

As the imperatives for a shift to fish culture emerge in rice-fish societies, an issue may 

be whether or not to try to replace the rice field fishery by developing culture in the 

paddy field or a pond. Culture in the paddy field attempts to recreate the 

environment of the rice field fishery, but with stocked and cultured species; pond 

culture effectively creates an additional artificial environment. It should be stressed 

that, even in pond culture, we are still talking about rice-based systems, since the 

farm economy where aquaculture takes place is usually still dominated by rice 

cultivation. In pond culture, the rice-based agricultural system offers resources for 

aquaculture but may also create and be constrained by competition in the use of 

those resources. 

While these systems are often discussed separately in dealing with small-scale 

aquaculture, it is important to point out that, in many cases, farmers actually 

combine both. The pond is often linked to one or more of the surrounding paddy

fields at certain times of the year or in certain culture seasons to facilitate 

management of the rice crop and, if water is available, to extend the fish growing 

period. Fry are frequently stocked in ponds early in the season, but may be released 

into the paddy field to browse during the rice cultivation season, before returning to 

the pond when the fields are drained. 

In developing aquaculture in rice-based farming systems, it is also important to 

understand the rich variety of those systems. At the broadest level of classification, 

rice is grown in irrigated, rainfed lowland, flood-prone, and upland ecosystems but 

very considerable differences exist within those systems. As is common in other 

traditional societies, rice farmers in South and Southeast Asia follow their own 

classification of rice lands, usually according to the level of inundation. For example, 

in Thailand and Cambodia, 

in rainfed lowland rice 

systems, it is common to 

speak of lower paddies, 

middle paddies and upper 

paddies, which can usually 

be broadly recognized by 

the height of the bunds 

between the fields. In both 

countries traditional land 

holdings in rainfed areas 

were often composed of 

paddy fields of more than 

one elevation to offset the 

threat of crop loss from 

both drought and flood. 

When rice fields were reallocated to individual households in Cambodia after the 

civil war, these principles were still used. The above classification refers only to rice 

lands, which can be cultivated normally in the rainy season. In Cambodia, there is a 

separate classification for lands which are too deeply flooded to allow wet season 

culture and can only be cultivated after the flood has receded. 

Each of these types of paddy field is associated with different varieties of rice. 

Commonly, the higher paddies with limited water holding capacity tend to be 

associated with early maturing varieties or light rice. Lower-lying lands tend to be 

cultivated with late maturing varieties probably with a taller growth habit; these rices 

are usually called heavy rice. At the extreme level of flood, farmers often cultivate 

floating rice, with long stems that grow with the rise of the water. Of course, in areas 

of improved water control, such variations have largely disappeared and the 

traditional local varieties have, in many cases, given way to higher yielding varieties 

of rather uniform characteristics. However, in rainfed areas, the second and third 

generation improved varieties have had to be adapted to the specific local 

conditions.

Planting 

The other key dimension of rice cultivation traditionally has been the planting 

method. Rice may be broadcast directly to the field or transplanted, that is grown in 

a seedbed in the early stages before being uprooted and replanted to the main 

field. The latter method enables farmers to start cultivation in areas with better water 

availability early in the season, to concentrate resources on the seedlings and to 

better control weeds. However, it is more labor intensive and difficult to practice on 

large plots and with limited labor supply. In general, the water levels in broadcast rice 

fields tend to be shallower, the plants closer together and yields lower. In an area of 

extreme out migration of labor such as Northeast Thailand, much of the rice land has 

been shifted in recent years from transplanting to broadcasting to save labor costs. 

These variations in the nature of rice cultivation have implications for the feasibility 

and productivity of rice-based aquaculture systems. 

Rice-fish culture 

As a result of donors’ and 

governments’ focus on 

sustainable rural 

development, food 

security, and poverty 

alleviation, rice-fish farming 

systems have received a 

great deal of attention in 

the recent past. Several 

reviews on historical, socioeconomic, 

and ecological 

aspects of rice-fish farming 

have been published in the 

past decade with either a 

global or a national focus. 

Country overviews have 

been provided for Bangladesh, China, India, Indonesia, Korea, Malaysia, Philippines, 

Thailand, Vietnam, and Madagascar. An extensive bibliography on diverse aspects 

of fish culture in rice fields was compiled recently. 

In contrast to rice field capture fishery discussed above, farmers deliberately stock 

the fish in their fields either simultaneously or alternately with the rice crop. They raise 

them up to fingerling or table fish size depending on the size of fish seed available for 

stocking, the duration of the fish culture period (which may cover two successive rice 

crops), and the market need for fingerlings or table fish.

Technical details of the few physical 

modifications (bunds, trenches, 

water inlets and outlets) required to 

make the rice field suitable for fish 

farming have been described 

elsewhere. It is, however, interesting 

to note the differences in refuge 

shape and size. The refuge can be a 

pond within or adjacent to the rice 

field, or a trench which may be 

central or lateral, or a combination 

of the two. Very great differences in 

the size of the refuge area can be 

observed. For religious reasons, 

farmers just dig a small sump in the 

rice field terraces in the Ifugao 

province in the Philippines while in 

Vietnam up to half the rice field is 

sometimes dug up because profits 

from fish sales exceed those from the 

rice crop. 

As noted above, traditional rice varieties are selected by the farmer for their 

suitability to agroclimatic conditions, topography, and also consumer taste. The local 

rice varieties are an important part of the wide biodiversity of plants and animals 

found in such systems. In large parts of Asia past increases in rice yields have mainly 

come from the gradual reallocation of land from traditional to the high-yielding 

modern varieties. 

Features of high yielding modern varieties 

● Short 

● Stiff-strawed 

● Fertilizer-responsive 

● Photoperiod-insensitive 

● Short to medium growth duration (100-130 days). 

The use of longer-stemmed and longer-maturing traditional varieties allows a higher 

water table and an extended period for fish farming. Although much of the 

expansion of rice-fish farming in the 1980s has been perceived to be associated with 

traditional rice farming, the case of the P.R. China with about 1.2 million ha under ricefish 

farming in areas almost exclusively planted to modern varieties shows that the 

use of new rice varieties is not a constraint for rice-fish farming. Deepwater rice 

varieties are adapted to grow quickly with rising water levels reaching several meters 

deep. The farming of fish in these waters must be community-driven as individual 

property rights cannot be distinguished anymore.

Costs for stocking and keeping fish within fenced areas may be high but can be 

shared among members. More importantly, the importance of capture fisheries and 

particularly access to these resources by the landless are issues of concern in 

deepwater rice-fish systems. 

Cultured fish species 

Many fish species are cultured in rice fields but only a few are commercially 

important. Fish species cultured in rice-fish farming: 

● omnivorous common carp Cyprinus carpio; and 

● planktivorous Nile tilapia Oreochromis niloticus. They feed low in the food chain 

and are therefore preferred species in the culture systems. 

● Other popular species 

● Barbodes gonionotus 

● Trichogaster spp. 

Often, the locally found wild fish 

such as snakehead Channa striata 

or smaller indigenous rice field 

species not only play an important 

role for food security and a 

balanced nutrition but are also 

important sources of income. 

While farmers generally tend to 

exclude predatory fish from their 

stocked rice fields, farmers in 

Northeast Thailand allow the fish to 

enter the field although many of the stocked fish fall prey to the wild species. This is, 

however, acceptable due to the high market value of the wild fish at local markets. 

Stocking 

The stocking densities used in rice-fish farming vary widely. In general terms, with a 

low number of fish stocked in the field, naturally occurring rice field organisms are 

readily available as "free fish feed". In low stocking densities, overall costs are lower 

and therefore this practice may be more suitable for resource-poor and risk-averse 

farmers who are still experimenting with their farming system. Higher stocking densities 

require additional fertilization and supplementary feeding. Feed resources from the 

farm are widely used for that purpose, particularly rice bran (although the alternative 

uses of bran have to be considered). Farmers may supplement the readily available, 

naturally occurring fish food organisms in rice fields by collecting supplemental feed 

from the rice field and surrounding wetlands. An example is the regular collection by

hand of bigger golden apple snails (which the fish could not eat directly) by farm 

household family members who crush them into fish feed sizes. 

Generally, integrated pest management (IPM) practices are recommended for ricefish 

farming. The use of pest and disease-resistant rice varieties is encouraged 

minimizing the need for pesticide application. In rice monoculture, the chance of 

pests reaching a population level to justify control action is usually low. Potential 

income from fish would outweigh pesticide costs. Also, from an IPM point of view, fish 

culture and rice farming are complementary activities because it has been shown 

that fish further reduce pest populations. Evidence from the FAO IPM Intercountry 

Program in Indonesia shows that, through IPM, the number of pesticide applications 

in rice can be reduced from 4.5 to 0.5. This not only saves costs, but eliminates an 

important constraint in the adoption of fish farming. Therefore training in IPM for many 

farmers participating in the regional program in Bangladesh, Indonesia, or Vietnam 

has been an entry point to start rice-fish farming. 

Simultaneous culture of fish and rice often increases rice yields, particularly on poorer 

soils and of unfertilized crops, probably because under these conditions the 

fertilization effect of fish is greatest. With savings on pesticides and earnings from fish 

sales, increases in net income on rice-fish farms vary considerably, but they are 

significant, with up to 100% reported increases when compared to returns from rice 

monoculture farms. 

Selected economic indicators for the comparison of rice and rice-fish farming 

Indicator Country Change(%) Comments 

Increase in rice yield equivalent Indonesia +20 

Income from fish as percent of 

total farm income 

Malaysia +7-9 

Net return Philippines +40 

Net return China +45 

Net return Thailand +18 -35 

Research station results, fish yield 

expressed expressed in rice 

equivalent 

Figures for owners and tenants in 

double rice in double rice cropping 

area, respectively 

Summary of results from nationwide 

field trials during the late 1970s to 

1987 in irrigated rice areas 

Results from four farm households in 

Hubei Province 

Figures for research station and 

farmer field, respectively 

Net farm income Thailand +65 Difference in rice yield equivalents

Cases with net return higher 

than rice monoculture 

Thailand +80 

Net benefit Bangladesh +64 +98 

Net profit Vietnam +69 

Total farm cash Vietnam 0 

Small pond aquaculture in rice-based agriculture systems 

20 out of 25 farms had higher netreturns 

from rice-fish farming than 

from rice monoculture 

Net benefits are higher in the aman 

or wet season and lower in the 

boro or dry season 

20% of the trench construction 

costs considered in capital costs. 

Operating costs increased by 83% 

for labor and 100% for irrigation, but 

had savings in the use of pesticides 

Mekong Delta, beneficial and net 

effects thought to be related to 

environmental sustainability, system 

biodiversity, farm diversification 

and household nutrition 

In small pond culture in rice-based agricultural systems, the key issue for aquaculture 

is resource availability. As the dominant element in the farm economy, the rice field is 

often the key resource for fish culture. The rice field offers several potential resources 

for fish culture, including rice itself. Aquatic plants such as duckweed and morning 

glory and a variety of other organisms including rice pests may be gathered as feed 

for fish (e.g., snails and termites). 

Milled rice offers two potential products for fish feed, the rice itself, either cooked or 

uncooked, and rice bran, which can be mixed with other feed or given separately. 

The latter is often favored in the region since it allows farmers to observe their fish at 

regular intervals. Naturally the availability of rice bran depends upon the yield of rice 

obtained. Higher yielding systems will potentially have more rice bran available. In 

Vietnam, for example, double-cropped rice in the so-called intensive zone of the 

Red River delta may offer up to 12 tons of rice per ha per year, providing almost a 

ton of rice bran. In contrast, the less intensive systems manage a total production of 

only half that amount. Unfortunately, there are other factors in the equation which 

have emerged with modernization. In Thailand, little of the bran from milling rice 

returns to the farmers. The bran is retained by local millers, who mill the rice for free, 

for rearing pigs. Farmers needing rice bran have to buy it from the market. In a sense, 

therefore, fish culture competes with the livestock sector’s demand for the available 

rice bran as feeds. In Vietnam, bran mixed with aquatic plants is often used as feed 

for pigs, rather than feed for fish. Pig manure becomes available as an input for 

fishponds. The more intensive the systems are, the higher the tendency to have more 

available manure. The balance in the use of these resources will be decided on

economic grounds. In southern Vietnam, in recent years, prices of pig meat have 

declined discouraging farmers from keeping pigs. However, if they produce local 

alcohol from rice, the resulting waste becomes a free source of feed for the pigs 

whose manure is used in fish culture. 

Another essential part 

of the typical ricebased 

farming system 

in Southeast Asia is 

draught livestock, 

usually water buffalo, 

kept for plowing, 

harrowing and 

transport of seedlings 

and harvested rice. 

Livestock also offers a 

potential source of 

pond fertilizers for fish 

culture, although ruminant manure in general is poor in nitrogen. Once again, 

however, availability depends on possible competition for resources. Where buffalo 

are gathered in stalls at night, manure is traditionally used as fertilizer for seedbeds 

and paddy fields, especially in areas of low fertility away from the flood plains. 

Ruminants may also compete for the use of pond water, particularly where water is 

at a premium as in Northeast Thailand. The problem with such areas is that the ricebased 

farming system offers a very limited source of nutrients. While 

recommendations for low-cost fish culture for poor farmers usually stress the use of onfarm 

inputs, the typical rainfed rice-farming system in the more inland areas of the 

region rarely offers an adequate nutritional base for fish. After many years of work in 

such areas, the AIT Aqua Outreach Program has concluded that on-farm resources 

need to be supplemented by inorganic fertilizers if fish production is to achieve more 

than subsistence yields. 

Prepared by: 

Harvey Demaine and Matthias Halwart

Rice-Based Aquaculture in China 

Rice-fish culture is traditionally practiced in 

many rice-growing provinces in China. 

Traditional rice-fish culture is mainly used to 

obtain additional protein for household 

consumption. However, recent developments 

in rice field-based aquaculture focus more on 

the economic benefits of this family-scale 

business. Over 6.7 million hectares of rice lands 

can be brought under these systems. 

Aquaculture commodities grown in a rice field 

result in significantly higher levels of income 

than when rice is grown alone. The price of fish 

is twice that of rice grain. In recent years, 

higher value aquaculture species, such as 

mitten-handed crabs and freshwater prawns, 

have been chosen by farmers for culture in 

their rice fields. The prices of freshwater prawns 

and mitten-handed crab are 10 - 50 times 

higher than that of rice, thus making these 

attractive economic propositions.

Models for integrating aquaculture into rice fields 

Rice field renovation 

The rice field is renovated to include the following elements: 

● elevated embankment to keep water and prevent cultured species from 

escaping; 

● ditches or trenches, sumps and refuges to provide shelters. The dimensions of 

these structures of different patterns depend on the farmed species. The 

structures should occupy about 15-20% of the total area; 

● sluice gates for inlet and outlet to regulate the water level to prevent losses; 

and 

● fence or enclosure of appropriate height, shape and materials to restrain 

crabs and frogs. 

Rice cultivars with strong stems should be planted. The variety should be able to 

tolerate manure application, especially if feeding and fertilization are applied during 

rice-fish culture. When the soil becomes very fertile, rice plants tend to lodge. 

However, there is scanty information about rice cultivars in rice-fish fields. Suitable 

rice cultivars for use in rice-fish culture have to be developed. 

Rice-fish culture

The species used for ricefish 

culture should meet 

the following 

requirements: 

● availability of 

quality fry and 

fingerlings in 

desired quantity; 

● desirable 

herbivorous or 

omnivorous feeding 

habits; 

● tolerance of high 

water temperature 

and low dissolved 

oxygen level at 

night; and 

● desirable growth rate/performance. 

Species for stocking 

Polyculture is used in most rice-fish culture systems. Several field-tested stocking 

models are available depending on the local situation. 

Most commonly used fish species for polyculture in rice fields are: 

● Common carp – Cyprinus carpio (several different strains or varieties) 

● Grass carp – Ctenopharyngodon idella 

● Crucian carp – Carassius auratus 

● Tilapia (Oreochromis niloticus) 

● Catfish (Clarias gariepinus gives high yields but its price is low due to poor 

acceptance by consumers. The hybrid between C. gariepinus and local 

catfish C. fuscus is better because of improved taste and high tolerance of 

undesirable environment conditions). 

Rice-fish culture is not a particularly good method for growing very young fish to 

fingerling size (about 3 cm) because of low survival rate. Nursery ponds are better for 

fingerling production. 

Rice-crab culture 

The culture of Chinese mitten-handed crab (Eriocheir sinensis) developed rapidly 

since 1994 probably because of high market value. A single crop of rice in a year is 

suitable for crab nursing or grow-out culture. To grow crabs in the rice field, a

peripheral trench should be dug with the following dimensions: width, 4-6 m. and 

depth, 1.2-1.5 m. Aquatic weeds should be planted in the water to provide shelter 

for crabs. 

Crabs can utilize the 

natural food produced 

in a rice field by 

manuring or fertilization 

activities for rice. 

Artificial feeds are 

applied for crab culture. 

One-third of the water in 

the field should be 

changed every 10-15 days to maintain desirable water quality (especially towards 

the end of the crop cycle). Dirty water often leads to molting problems and poor 

appearance at harvest (and low prices). During culture, the use of chemicals toxic 

to crabs should be avoided. Harvesting should be done before the temperature 

drops to 12°C to prevent crabs from burrowing into the mud. 

Rice-prawn culture 

The culture of native freshwater prawn Macrobrachium niponensis or the exotic 

freshwater giant prawn M. rosenbergii is a relatively new aquaculture practice in rice 

fields. Though the native species is smaller than the exotic prawn, it demands a 

higher price in the domestic market.

Preparation of a rice field for prawn culture 

is similar to that for crab culture. For local 

prawn, M. niponensis, brooders carrying 

fertilized eggs are stocked between mid- 

May and mid-June in a small cage installed 

in the sump for hatching. Brooders, along 

with the small cage, are removed after the 

hatching of eggs. The stocking density per 

hectare is 3-3.75 kg of 4-6 cm brooders. 

Larval development, which lasts about 15- 

20 days, takes place in the rice field. 

Natural food organisms and supplementary 

feeds like soybean milk greatly influence this 

development. Larvae estimated at 225,000- 

300,000/ha continue to grow in the field up 

to November. Crushed snails, clams and 

commercial prawn pellet feeds are applied 

during grow-out. The feeding rate is 0.5 kg 

per 10,000 prawns. This is increased by 0.5 

kg every two weeks. 

Harvesting is done in late November to 

December. Market-size shrimps are taken 

out and sold live. The small ones are 

returned to the fields for further growth. 

For M. rosenbergii, seeds are purchased from hatcheries and the post-larvae 

stocking density in the rice field is 30,000 per ha. The routine management is similar to 

M. niponensis. Harvest should be done in October before the temperature drops. 

References 

Birley, M.H. 1998. Internet Conference on Integrated Bio System, 1998. 

Jianzhong, B. 1997. The 6th Industrial Revolution: Symposium of the Industrialization 

Strategy of Modern Agriculture: A review. S & T Daily. 

Kangmin, L. 1988. Rice-fish Culture in China: A Review, Aquaculture, 71 (1988) 173- 

186. 

Kangmin, L. and P. Yinhe. 1992. Rice Fields as Fish Nurseries and Grow-out Systems 

in China. In ICLARM Conference Proceedings 24. 457 p. 

Mingsen, Z. 1994. Rice Crab Culture Techniques. Journal of Aquaculture 1994 (2).

Neng, W., L. Guohou, L. Yulin and Z. Gemei. 1988. A Role of Fish in Controlling 

Mosquitoes in Rice Fields. In K. MacKay, ed. Rice-Fish Culture in China. p 213-215. 

Qinghe, H. 1998. 21st Century Calls for Feed Revolution. Science & Tech Daily 11 

April. 

Yin P. 1985. Fish and Frog Culture Techniques in Paddies. Jiangxi Provincial 

Fisheries Research Institute, Manuscripts. 

Prepared by: 

Li Kangmin

Enhancing the Performance of Irrigation Systems 

through Aquaculture 

Harvesting fish from irrigation systems, sometimes involving some form of husbandry or 

even culture, has been a long time practice. Although seldom recorded, it seems to 

have been widespread in the tropics and subtropics, especially in rice fields. 

Improved management of land-based crops and the successful raising of aquatic 

organisms were not generally considered to be compatible. But with the advent of 

integrated crop protection (e.g., integrated pest management), this situation has 

changed. 

Irrigation systems using stored or diverted water have increased exponentially during 

the past 50 years, but the expansion of fish farming within these irrigated systems has 

not kept pace. The integration of fish farming could significantly mitigate some of the 

negative effects associated with irrigation systems, such as an increase in human 

disease vectors.

Water use 

imperative 

Currently, water scarcity 

is emerging as the 

dominant constraint in 

efforts to expand food 

production. Increasing 

irrigation efficiency and 

water productivity – 

getting more crops per 

drop – must therefore 

become one of the top 

priorities. Integrated 

water resources 

management is now 

widely recognized as a 

basic principle of water 

management. 

Possibilities for integration 

An approach to fish farming development at 

the irrigation system level is proposed. The 

reservoir fishery, particularly in large shallow 

reservoirs as found in Sri Lanka, is highly 

productive. The farming of fish in Chinese 

reservoirs has also resulted in spectacularly 

high yields. The culture and capture of fish in 

irrigation canals are practiced in several 

countries such as Egypt, Pakistan, China and 

Thailand. Pond culture can be highly 

productive as Chinese and other Asian

experiences show, and fish capture and culture in rice fields have received new 

impetus with the increasing spread of integrated pest management practices. Even 

though substantial profits can be achieved when fish farming is done in individual 

irrigation components, it is proposed that the development of fish farming in several 

or all components of the system is more likely to succeed because it will alleviate 

constraints that are inevitably encountered if only one component is developed 

(Fernando and Halwart, 2000). 

An example is the use of rice fields as fish nurseries. If only rice fields were used for fish 

farming, the fish harvested at the end of the cultivation period would generally be 

too small for human consumption. However, if the fingerlings can be sold for growout 

in other components of the irrigation system, e.g., reservoirs or canals, the 

constraint of harvesting small, unmarketable fish can be overcome. On the other 

hand, grow-out operations are often constrained by limited fish seed supply. The 

demand for fingerlings can be met by rearing fish fry in nearby rice fields under 

concurrent or rotational systems. 

For example, stocking material of species suitable for reservoirs can be obtained 

from irrigated rice fields where the short maturation period of the crop only permits 

the harvest of fingerlings. If a pragmatic and flexible approach is applied to use all 

aquatic habitats for fish production and conservation, there could be a year-round 

supply of fish and a minimum of wastage of stocks of cultured fish. 

In many countries, fish seed is now relatively accessible even in inland areas.

Permanent water bodies should be stocked with a central pool of culture species 

harvested from short-lived habitats serving as nurseries. A flexible system of moving 

culture fish within the system of habitats should be feasible. 

The use of high-yielding fish of good quality is essential for economic viability. In areas 

where a high diversity of fish with the requisite biomass of desirable species already 

exists, the indigenous fish can be harvested. However, the yields may only be 

adequate for low-income rural areas. Common carp has been a preferred cultured 

species. Tilapia is proposed as an alternative because the fish is cheap to raise, gives 

high yields and is quite palatable. 

Aside from economic revenues, this type of integration also leads to ecological and 

social benefits. High densities of fish in irrigation systems enhance the yield of land 

crops, minimize crop pests, and reduce the populations of vectors of diseases in man 

and domestic animals. 

From a planning and development perspective, the major challenge for the future of 

fish farming in irrigation systems is likely to be related to issues of inter-agency 

coordination, consultation and, in some cases, external mediation to harmonize 

interests of the different line agencies. 

Utilizing several components of the irrigation system can boost fish 

production – From rice field nursery to cage grow-out 

Traditionally, rice-fish systems in West Java, Indonesia, supplied 

seed fish for further growing in family ponds and fish for direct 

consumption by people living within the rice-growing districts. 

Fish markets increased in size due to tremendous population 

pressures in West Java. The number of ponds and rice-fish 

systems also increased. Running water systems moved from the 

laboratory to commercial-scale, increasing the demand for 

seed fish and contributing to the expansion of rice-fish and pond nurseries. In 

the 1980s, demands for freshwater fish continued to expand, but the number 

of traditional fish ponds remained relatively constant due to urbanization. 

Rapid development of reservoir cage culture created increased demand for 

seed fish for stocking, resulting in further expansion of rice fish nursery systems. 

In the Cianjur and Subang Regencies, West Java, a combined minapadipenyelang 

nursery system produced four crops of fish and one crop of rice 

with total yields of 370 kg/ha and 5,667 kg/ha, respectively, in six months. 

(Costa-Pierce, 1992).

References 

The Challenge: Consultation and Coordination 

The participation of all resource users and other stakeholders at an early 

stage is indispensable to effective land use planning and zoning, not least 

because of their intimate knowledge of local socio-economic conditions 

and the state of natural resources. At the government level, the functions of 

the various agencies with regulatory and development mandates need to 

be well coordinated. Two broad distinctions can be made in the wide range 

of possible institutional arrangements leading to integrated planning and 

development at irrigation system level: 

Multisectoral integration. This involves coordinating the various 

agencies responsible on the basis of a common policy and bringing 

together the various government agencies concerned, as well as other 

stakeholders, so they can work towards common goals by following 

mutually agreed strategies. 

Structural integration. Here, an entirely new, integrated institutional 

structure is created by placing management, development and policy 

initiatives within a single institution. 

Multisectoral coordination tends to be preferred, since line ministries are 

typically highly protective of their core responsibilities, which relate directly to 

their power base and funding. The establishment of an organization with 

broad administrative responsibilities overlapping with the traditional 

jurisdictions of line ministries is often likely to meet with resistance rather than 

cooperation. Integration and coordination should be considered as 

separate but mutually supportive. 

Source: Willmann, Halwart and Barg. 1998. 

Costa-Pierce, B.A. 1992. Rice-fish Systems as Intensive Nurseries, p. 117-130. In: C.R. 

dela Cruz, C. Lightfoot, B.A. Costa-Pierce, V.R. Carangal and M.P. Bimba (eds.) 

Rice-fish research and development in Asia. ICLARM Conf. Proc. 24, 457 p. 

Fernando, C.H. and M. Halwart. 2000. Possibilities for the integration of fish farming 

into irrigation systems. Fisheries Management and Ecology 7: 

45-54. 

Willmann, R., M. Halwart and U. Barg. 1998. Integrating fisheries and agriculture to 

enhance fish production and food security. The FAO Aquaculture Newsletter 20: 4- 

9. 

Prepared by: 

Matthias Halwart and C. H. Fernando

Rice and Fish Culture in Seasonally Flooded 

Ecosystems 

Farming in a flood-prone environment 

Seasonally flooded ecosystems play an important role in the livelihoods of people in 

Asia. These areas are also the densely populated valleys and deltas of the major 

rivers: the Ganges, the Brahmaputra, the Godavari, the Irrawaddy, the Chao Phraya 

and the Mekong. In these floodplains, farmers have traditionally grown rice in a 

variety of systems. The main system, in which rice was farmed in the post-flood 

season in shallow-flooded areas (5 to 50 cm), was to sow rice into the moist areas 

after water had just receded and to grow the crop into the dry season. A different 

set of systems was used in the deep-flooded areas (50 cm to 6 m) where farmers 

grew either rice varieties that were submergence-tolerant (up to 1 m for four weeks), 

or grew floating rice varieties in areas flooded at greater depths (up to 6 m) for 

longer durations. In these systems, seeds were sown into the dry or already moist soil 

just before the rainy season and the rice harvested at the end of that season. 

These floodplain areas also play a very important role in the supply of living aquatic 

resources (LARs) during the flood season. During this important time of the year, 

people engage in a wide range of fishing activities in thee flooded areas, harvesting 

fish, crustaceans, mollusks, frogs, turtles, insects, etc. The harvests play an important 

seasonal role in the diet of rural poor as the highly nutritious foods make up for the 

nutrient deficiency during the preceding dry season. They are also a major source of 

income, especially for the landless, who often rely on these activities for their entire 

annual income and therefore are highly dependent on the existence of, and their 

access to, these resources. 

In the last few decades, flood-prone ecosystems in Asia have undergone dramatic

changes due to the construction of Flood Control, Drainage and Irrigation (FCDI) 

systems. Flood patterns have changed and the abundance of LARs have been 

reduced. Through increased availability of irrigation, a second crop of rice is now 

grown in the dry season. As these are high-yielding rice varieties and their cultivation 

periods last almost to the onset of the floods, farmers in many areas who were 

previously culturing rice during the flood season have abandoned this practice, 

leaving the areas fallow. Rice yields from the flood season are low as improved 

varieties are not available. 

An opportunity for increased production is the cultivation of fish in the deeper 

flooded areas. Two culture systems can be distinguished: (1) sequential culture of dry 

season rice followed by stocked fish only during the flooded season (i.e., without 

rice) in an enclosed area (e.g., as in a fish pen); (2) simultaneous culture of stocked 

fish and submergence-tolerant rice varieties or floating rice varieties. On an annual 

basis, these approaches offer an overall improvement of agricultural production 

from a given area of land through a diversification of technologies. In the flooded 

area, individual land holdings are not visible. Therefore, activities require a group 

approach by the rural community. These include the landless who have traditionally 

accessed the flooded areas for fishing, but would lose this essential resource if they 

were denied access because the areas were stocked with fish (i.e., which have 

become a commodity, aside from the existing "wild" fish). 

Basic principle 

After the cultivation of dry season rice, when fields are flooded to a depth at which 

individual ricefield boundaries (i.e., bunds) cannot be distinguished, floods form a 

water body for 4 to 6 months. The farm is usually left as flooded fallow, but it can be 

used to grow deepwater rice and/or fish. Given adequate topographic site 

characteristics (i.e., a lowland area of rice plots almost enclosed by natural elevated 

lands, raised homesteads, dams for roads, train tracks, canals, etc.), ideally it should 

be such that only a small bottleneck-type opening is left to let floodwaters in, it is 

possible to close the bottleneck with a fence and stock the enclosed water body 

with fish. Deepwater rice can be grown as a substitute to the second dry season rice 

crop if the field is left fallow during the dry season. It is sown into the dry soil just 

before the flood season. 

Criteria of managed areas 

The areas considered for concurrent or sequential rice-fish culture are flooded 

annually and have shallow (30 to 80 cm) to medium (80 to 150 cm) flooding depths. 

Site selection is based on the following criteria: 

● adequate size, i.e., 2 to 10 ha; 

● natural or existing artificially elevated lands (e.g., homesteads, dams, etc.)

enclose the area on three sides to allow fencing off; 

● stakeholders of a water body, including landowners, leaseholders, landless 

fishers (who may have customary rights to fish in the flooded waterbody but 

are denied access during the dry season) can be involved in a shared 

management arrangement; and 

● groups are not too large (

Flooded field with deep water rice stocked with fish 

Comparison of dry season rice field (upper drawing of bird’s-eye view of village) 

with two options for cultivation in flooded fields: 1. Flooded field stocked with fish 

only (middle drawing); 2. Flooded field planted with deepwater/ floating rice 

stocked with fish (lower drawing). 

Group formation, cooperation and sharing arrangements 

Groups are usually composed of around 20 households each, consisting of 

landowners, fishers and landless laborers. Landowners may be participating or nonparticipating. 

Non-participating landowners receive a share by just providing their 

land, but are otherwise not active in group activities. Actively participating 

landowners in the group activities receive an additional share for their role as group 

members aside from what they already receive as landowners. 

Farmers groups will have to negotiate and agree on cooperative sharing 

arrangements, rules, technical details and schedules of operation. These may be 

influenced by other existing agreements and ongoing conflicts. 

Sharing arrangements include rules of access, duties and rights of participating 

(active) and non-participating (passive) members; investors of land (granting use 

rights) versus investors of labor (landless with customary access rights to fishing in 

season), etc. 

The group covers all costs from the proceeds of rice and/or fish sales. A common 

arrangement in Bangladesh for sharing the remaining returns is 40% for landowners, 

and 60% for group members. Landowners are usually keen on joining the activity as 

they receive returns from land that is usually fallow during the flood season.

Enclosure 

The enclosure should be 

designed and built by the 

cooperating farmers. It is usually 

a fence made of locally 

available materials like 

bamboo, reed and wood, but 

can also be made of netting 

material, which lasts longer if 

available locally at affordable 

cost. 

In some locations, natural 

saucer-shaped depressions not 

connected to another open 

water body or river provide 

ideal situations for fish culture. 

The fish could not escape and 

construction costs are eliminated. Additionally, farmers get the chance to 

implement different rice cultivation strategies in the shallow and deeper parts of the 

water body. 

Investments 

The groups will have to invest in a fence or dike (where necessary), fingerlings, labor 

(fence or dike construction and maintenance, feeding, harvesting) to successfully 

master the activity. 

Sequential dry season rice and flood season fish culture 

If farmers decide to maintain two crops of high-yielding rice varieties per year and 

do not want to substitute the second crop for deepwater rice, specifically stocked 

fish species can be grown within the enclosure. 

Concurrent deepwater rice and fish 

After transplanting rice, bigger fingerlings can be stocked into the ricefields and 

reared until the water dries up, usually after rice harvest. Bigger-sized fingerlings are 

costly, but the expenses can be recovered by increased growth and survival (i.e., 

less escapes and losses to fish predators) and ensuing greater returns. The availability 

of larger fingerlings in adequate sizes and quantities can pose a problem and should 

be planned for, e.g., through fry-to-fingerling rearing in rice fields in the preceding 

dry season, or in small ponds in the deepest parts of the enclosed area.

Deepwater rice technologies (for concurrent rice-fish culture) 

Rice varieties 

Use taller rice varieties, characterized by (1) more than 160 cm total 

plant height at harvest time, and (2) a taller seedling height. 

Fertilization of deepwater rice 

Fertilizers should be given but only in basal dose form for deepwater rice. 

Pesticides 

No pesticides should be applied. 

Fish technologies 

Species combinations 

Fast growing species like silver carp, common carp, rohu, silver barb and Nile tilapia 

are recommended. Other species chosen by farmers for stocking are grass carp, 

catla and snakeskin gourami. 

Fry and fingerlings of naturally occurring fish species can enter into the enclosed 

areas at the time the flood rises. The indigenous or "wild" species can grow and 

reproduce for harvest by small-scale fishers. 

Stocking density 

Stock at 2,000 to 4,000 per hectare, depending on the size of fingerlings (around 5 to 

15 g) at stocking. 

Feeding of fish 

Fish can feed on natural food and by-products available in the ricefield, both in 

concurrent culture and in sequential culture without rice. However, when growth is 

slow , supplemental feed (e.g., rice bran) may be given at a later stage. 

Additional technical options 

With a short-duration rice crop, an intercrop of soy bean, maize, green leafy 

vegetables, etc., can be grown before the flood.

Benefits 

Fish yield. 500-1200 kg per hectare. 

Rice yield. The basic rice yield is about 10 t/ha/y for two crops. The introduction of 

fish does not result in rice yield decrease. In fact, it has been shown to increase 

marginally by about 500-1000 kg/ha/y. 

Increase in profitability. US$300-400/ha/y, or an increase of 30 to 40% over the 

previous profitability of US$1000. 

Impact on landless laborers. Income and per-capita fish consumption increased 

substantially. 

Role of external support 

To start this type activity through a demonstration in a given area, the initial input of 

local service institutions, NGOs or other organizations is necessary to provide local 

experience and facilitate site selection, group formation, decision on technical 

issues and other processes mentioned below. 

From experience, as a result of the demonstration, other groups establish themselves 

without external inputs or stimulus and establish their own sharing arrangements. 

Second-generation groups arrange for their own funding and other logistical 

requirements, such as fingerling purchase and transport, while first-generation groups 

tend to remain dependent for funding and other support on the service institution 

that helped establish them. 

Site selection survey should be conducted together with a group to enhance 

comprehension. The idea can be raised during discussions with individuals, then with 

groups of landowners, landless, etc. Meetings to facilitate the presentation of the 

idea to a larger group, including discussions towards consensus, establishment of a 

"management committee", and to the formulation of a sharing arrangement, should 

be conducted. External groups should act as credible provider of technology and 

witness and arbitrator. It is necessary to assist groups in the selection of fish species 

and rice varieties, stocking densities and sourcing of fingerlings and to provide 

guidance on the proper transport and stocking method to ensure high survival. 

Repeated visits are necessary to ensure smooth interactions among group members 

and to facilitate meetings to solve/settle problems and brewing conflicts. 

Farmers/actors who will do the work (fence construction, stocking, feeding) should 

be trained and the group should be assisted in financial accounting, harvest 

methods and equipment (nets), marketing of harvest and the actual sharing of the 

yield both in terms of fish and cash.

Startup loans 

The initial investment in the fence can be considerable and groups might hesitate to 

adopt a new technology with risks involved, especially when its effectiveness has not 

yet been demonstrated to them. Farmer groups may be wary of the investment in 

fingerlings for stocked fish. Startup loans, to be repaid upon harvest, have eased the 

adoption process and given the groups confidence to embark on the activity. 

Sustainability 

Fence material may decompose after one season and has to be replaced at high 

cost sometimes. Socioeconomic factors include setting aside part of the returns for 

reinvestment the following year on a fence (mending, renewal, etc.) and for 

restocking (fish, rice). Social factors include group enforcement of rules and 

elements of the agreement. 

Factors influencing adoption 

Socioeconomics 

Homogeneity of households in a group is a positive factor for adoption of 

technology. Heterogeneity of households within a group will create problems for the 

operation, since complex social issues and factors influence success. With larger 

groups, there may be economy of scale but also an increased risk of internal 

conflict. 

Biophysical 

factors 

Fluctuations in the onset and duration of the rainy season, as well as average 

flooding depth, affect rice-fish culture. With longer duration rice -- or with floods rising 

before rice is harvested -- farmers cannot grow an intercrop or transplant deepwater 

rice. Harvesting rice with rising water can be difficult and laborious. With the water 

rising, deepwater rice can only be broadcast. It is more straightforward to undertake 

rice-fish culture in a relatively flood-controlled environment. 

Biotechnical factors 

Availability of fingerlings of species (desired by farmers) in appropriate sizes and 

quantities for stocking can pose problems and should be planned for. 

Institutional issues

Presence of, or possibility of forming rural organizations and/or farmers groups, is 

essential. 

Potential areas for adoption 

Medium-flooded areas of Bangladesh, Mekong Delta of Vietnam, and eastern India 

can be brought under this technology. It seems possible to introduce the technology 

into similar environments in Africa and Latin America, depending on further on-farm 

testing. 

Validation status 

General schematic annual 

calendar representation of 

comparison of culture system 

with two high-yielding rice 

culture periods withou t 

utilization of the flooded area 

for fish culture during the flood 

season (upper calendar) with 

two options for cultivation in 

flooded fields: 1. Flooded field 

stocked with fish only between 

two HYV culture periods 

(middle calendar); 2. Flooded 

field planted with deepwater/ 

floating rice stocked with fish 

with only one HYV cropping 

cycle as deepwater rice 

requires earlier sowing or 

transplanting and has a longer 

culture period (lower 

calendar). Intermittent crops 

could be grown in the period 

between the HYV and the 

deepwater rice cycles. 

Three years of field trials with two communities in the Red River Delta, three 

communities in the Mekong Delta, and a total of nine communities in Bangladesh. 

This technology has been adopted in provinces in northern Vietnam by local 

governments and the Department of Science and Technology with considerable 

investment and is being disseminated among farmers. 

In Bangladesh, the country-wide operating NGO – Proshika – has adopted the 

technology as part of its rural development program. The Department of Agriculture

Extension will implement the technology on a wider scale in one of its projects 

(ADIP/DAE) funded by IFAD. 

References 

Catling, D. 1992. Rice in Deep Water. International Rice Research Institute, Manila, 

Philippines. 542 p. 

Hargreaves, T.R. 1975a. Improved Rice Varieties Needed for World’s Deep Water 

regions. The IRRI Reporter 3/75. 

Hargreaves, T.R. 1975b. Characteristics and Culture of Floating Rice. The IRRI 

Reporter 3/75. 

IIRR and ICLARM. 1992. Integrated Agriculture-aquaculture Technology 

Information Kit. International Institute of Rural Reconstruction, Silang, Cavite, 

Philippines, and ICLARM. 

Prepared by: 

Mark Prein and Madan Mohan Dey

Increasing Wild Fish Harvests by Enhancing Rice 

Field Habitats 

Aside from producing the carbohydrate staple, the rice paddies of Bangladesh are 

also known as reliable sources of fish. Large quantities of fish enter the flooded 

paddies during the rainy season, spawn and grow there. In the past, this was possible 

without any active management as the rice fields were full of indigenous small fish. 

Today, however, the quantity and diversity of wild species have decreased 

significantly. If this downtrend continues the fishes in the rice fields and flood plains 

may completely disappear. This will have dire consequences for poor people who 

depend largely on the rice fields for fish, a major source of animal protein in their 

diet. 

Taking this into consideration, the Aquaculture Unit of New Options for Pest 

Management (NOPEST) of CARE Bangladesh (funded by European Union) 

conducted a small-scale survey in its project area in Mymensingh and Comilla 

districts to: 

● identify the naturally available fish species in rice fields; 

● identify their annual migration patterns (how/when they arrive in the rice 

fields); 

● examine those factors leading to a decrease in the amount wild fish in the rice 

fields; 

● review methods of improving water management at the farming community

level, which can restore or improve the fish habitat. 

Wild fish yield and diversity in rice fields 

In the study areas, it was found that wild fish production without any intervention was 

about 60-85 kg/ha during amon (a rice-growing season in Bangladesh lasting from 

July until December), which is a significant amount. 

However, fish production in the fields under rice and fish cultivation averages 125 

kg/ha and some farmers can harvest up to 200 kg/ha within a five-month cultivation 

period. Higher yields are due to the location of the plots near lowland water-bodies 

(beel), and the use of ingenious traditional equipment in dikes. The dikes allow fish to 

enter the plot but prevent them from swimming out. 

Species diversity fluctuates from 

area to area and even plot to 

plot because of the various 

distances of the fields to a beel 

and the number of connections 

between them. As the distance 

to the beel decreases, fish 

quantity and diversity increases. 

Good beel connections 

facilitate wild fish migration. 

Longer periods of inundation 

also result in bigger catches as 

higher amounts of rainfall and 

longer monsoon periods 

contribute to the spread of indigenous wild species. Early season rains are important 

but the consistency of rainfall is more important as it is during dry periods that the 

diversity and the number of fish decrease. 

significant numbers. 

Fluctuations in species diversity are also due to 

pesticide applications. Fields containing 

pesticide residues make less favorable habitats 

for fish, resulting in lower yields and fewer 

species. 

Species mentioned in Table 1 are perhaps the 

only ones now generally found in rice fields of 

Mymensingh and Comilla. Some other species 

(including major carp) were found but not in

Table 1. Common and scientific names of the fish species in the study areas, their 

frequency, characteristics and their sensitivity to pollution 

Common local 

name 

Scientific name Frequency 

Characteristics (all 

species bred during 

moonsoon) 

Sensitivity 

to 

pollution 

Kuche Monopterus cuchia + Carnivorous - 

Darkina Rasbora daniconius ++++ Omnivorous - 

Chale puti Puntius chola +++ Plankton feeder --- 

Taki Channa punctatus +++ Carnivorous - 

Lal kholisha Colisa fasciata +++ Omnivorous -- 

Koi Anabas testudineus ++ Carnivorous -- 

Local chingi ++ Detritus feeder -- 

Mola 

Amblyphyrangodon 

mola 

++ Plankton feeder ---- 

Kachiki Corica soborna ++ Omnivorous --- 

Tara bain 

Mastocembelus 

aculeatus 

++ Bottom feeder -- 

Tengra Mystus vittatus + Carnivorous --- 

Shing Heteropneustes fossilis + Carnivorous - 

Gasua Channa orientalis + Carnivorous - 

Shol Channa striata + Carnivorous - 

Magur Clarias batrachus + Carnivorous - 

Gutum Lepidocephalus spp. + Omnivorous -- 

Legend 

+ = Least frequent - = Least sensitive 

++++ = Most frequent ---- = Most sensitive 

Role of the rice field in the life cycle of wild fish 

Wild fish enter and thrive in the wet paddy environment so rice-field fishery is 

possible. Traditionally, no management inputs were necessary for these fields. 

However, farmers still know how the fish came to be in their fields. 

According to the farmers 

● Wild fish come from nearby rivers, canals, and lowland water bodies when the 

fish enter the fields through channels, drains, or ground surface runoffs during 

the rainy season (May-August). In most cases, beels are found to be the source 

of wild stock in the paddies. 

● Water runs off towards the beel areas and the rice paddies become 

inundated and merge with the beels. A single shallow sheet of water is formed 

as the dikes are flooded, which serve as the spawning grounds for wild fishes. 

● Broods of wild fishes move towards the upland areas where the water is 

shallower. There, the fish spawn and lay their eggs, the rice field being an

integral part of their life cycle. Rice fields also act as nursery grounds providing 

a favorable habitat for spawn and fry. This is reflected in farmer’s comments 

such as "In the monsoon season when we catch fish from the canals or drains, 

the fishes’ bellies are full of eggs, while at the end of monsoon the harvested 

fish are without eggs and small in size". 

● After the monsoon, when the water flow stops, the migrant fish and their 

juveniles try to return to the beels. Some of them make it back to the beels and 

continue their life cycle but most are unable to escape from the rice fields 

because of the dikes and those that remain are eventually trapped and 

caught. 

Factors responsible for the decrease in fish stock 

Loss of habitat and sedimentation 

Expanding network of flood control, irrigation structures and roads built over the last 

twenty years are interfering with the cycle of fish regeneration. These structures block 

migration pathways and degrade natural spawning and feeding grounds. 

Dying vegetation in the marshy lowland water and the annual accumulation of soil, 

nutrients and debris carried by the monsoon rainwater through the canals towards 

the beel lead to siltation and sedimentation. These deposits reduce the surface 

area, depth and water carrying capacity of both the beels and canals. 

Drying out 

During the dry season, majority of these water bodies dry out and as a result no fish 

are left to spawn in the monsoon. As a result, less brood fish can migrate to the 

upland rice field areas to spawn. 

Water pollution 

Household wastes and fertilizers in the lowland water bodies, come from the runoff of 

agricultural land during the monsoon season. This is a problem in the beels 

(permanent habitat of wild brood fishes) during the dry season when the water level 

is at a minimum resulting in the growth of plants and algae. These plants cause 

oxygen depletion resulting in frequent suffocation of fish and oxygen is further 

depleted through the decaying process of decomposers. 

Introduction of high yielding varieties of rice 

Farmers have increased their use of pesticides since they began to cultivate high-

yielding rice varieties. They perceive these varieties require more pesticide and 

chemical fertilizers, hence there is a continuous increase of pesticide and other 

chemical residues in the beel through rice field run off. This has an adverse impact 

on the reproductive system of fish among others. These pesticide residues remain in 

the water body or rice fields year after year, having a cumulative negative impact 

on aquatic life. There has been evidence from studies on rice field fisheries in 

Malaysia that prior to the introduction of high yielding varieties, capture production 

averaged 135 kg/ha in the range 10 to 400 kg/ha. More recently however, based on 

records of capture production in Asian countries, the range is from 1.5 to 84 kg/ha. 

Disease 

Indigenous wild fish species such as snake headed fish, local cat fishes, Puntius spp., 

Anabas spp., etc., are more susceptible to ulcerative disease. In the past ten years, 

these species have been greatly reduced. The disease causing factors have not 

been diagnosed yet, but may have spread into Bangladesh from neighboring 

countries. In some instances, fish develop immunity to certain diseases and this may 

well happen in Bangladesh over the years. 

l Over fishing 

In monsoon, during spawning and the migration towards rice fields, traps, small mesh 

sized drag nets and current nets are placed in locations close to each other 

throughout the narrow waterways. There is very little chance of any fish escaping 

through these traps to spawn. With increasing human population, more people are 

involved in wild fish harvest with a greater use of various types of equipment and 

nets. This, combined with traditional seasonal fishing, leads to an intensification of 

fishing thus reducing the wild fish population in the rice fields. Many rice fish projects 

actually do not recommend that wild fish should be present in the rice field together 

with cultured fish. This is also responsible for the reduction of wild fish stock. 

Interventions to restore and improve fish habitat 

Community responsibility

The Bangladesh government 

has plans to implement huge 

flood control and irrigation 

projects and construct more 

roads and highways. If these 

were planned well, the effect 

on the life cycle and migration 

patterns of wild fish may be 

minimal. Through proper 

management and 

maintenance of the drains, 

brood fish habitats would not 

be lost. As these interventions 

affect the community, they 

should be involved to ensure 

good management. These 

communities should be responsible for ensuring that waterways are dug out regularly 

and dead canals are re-excavated. 

Integrated pest management (IPM) 

IPM may improve fish habitats over time, leading to an increase in fish populations. 

Intervention should consider that changes to the overall crop management will 

have a profound impact on the rice ecology. A healthier rice ecosystem will offer 

wild fishes a sound environment to breed and live in. 

Use of dikes 

Some farmers 

construct dikes in the 

lowest portion of the 

rice field. During 

drought these provide 

shelter and after 

draining the field for 

harvest, fish can easily 

be collected from 

there. These dikes 

normally surround the 

fields so by raising the 

dikes, fields are 

protected from 

flooding, which 

removes fish from the 

field. Farmers fit traps 

Using traps in dikes allows wild fish inside 

the ricefield and prevents them from 

escaping.

in the dikes in 

monsoon season that 

allow fish to enter the 

field from the open 

water but prevent 

them from swimming 

out from the rice field. 

The objective of this 

system is to collect 

wild broods, allowing 

them to grow in the 

rice fields until the dry 

season. 

Farmers also use branches of "shewra" tree that attract the fish to take shelter within 

the dikes. This is an indigenous management technique leading to yield rates that 

are high even in comparison to rice-fish cultivation production. After harvesting rice 

in November and December, the fish harvest can continue until January as the 

branches provide a refuge for the fish.

Conclusion 

Most 

development 

organizations 

avoid working 

in lowland 

areas that are 

remote and 

susceptible to 

flood, 

considering it 

unfeasible in 

terms of 

project 

outputs. 

Hence, people 

of these 

lowland areas 

are deprived 

of all kinds of 

development 

activities and 

they 

unwittingly 

destroy their 

wetlands. 

Increased 

understanding 

of the rice field ecology would increase productivity and indigenous wild fish 

numbers during the monsoon season. 

Adopting this approach, fish harvest could go up to 250 kg/ha/crop in amon 

with little effort (confirmed from trials). In rice fields where wild fish are 

allowed to enter through the bana (bamboo net), even up to 400 kg/ha 

can be harvested. Rice yield and stocked exotic fish production were not 

affected unlike rice fields completely surrounded by massive dikes. 

The wetlands of Bangladesh should be incorporated into small-scale development 

programs to create new opportunities for deprived farmers. When they are 

empowered to learn about rice field ecology and water management, they will be 

able to make better decisions on wild fish conservation. 

Reference 

Soong, M. K. 1950. Fishes of the Malayan Paddy Fields III: Keki Catfishes. Malay, 

Nat. J. S. p 88-91.

Prepared by: 

A. K. M. Reshad and Harald van der Hoek

Polyculture Systems: Principles and Basic 

Considerations 

Polyculture is a strategy to utilize the different food 

niches in an aquatic system and harness maximum 

possible amounts of nutrients and energy in the form 

of fish. Aimed at harvesting the productivity at 

different trophic levels, the approach incorporates 

different fish species, based on the availability of food 

and the feeding habits of the species. 

Food chains in a pond system 

The polyculture systems put considerable emphasis on the natural productivity of the 

water bodies. Photosynthetic and heterotrophic food chains operate in the process 

of energy transfer from solar radiation to the fish biomass. Producers, consumers and 

decomposers are the key players in these chains. 

In a photosynthetic food chain, the primary producers (phytoplankton and 

bacterioplankton) synthesize organic matter and utilize inorganic nutrients in the 

presence of solar radiation. These are grazed by the zooplankters (primary consumer 

level) which, in turn, are preyed upon by the higher level consumers like fish and

shellfish. 

The heterotrophic food chain is characterized by intense activity of the 

decomposers. These decomposers degrade organic matter into simpler compounds 

that are further mineralized into inorganic nutrients. The detritus resulting from the 

process becomes an important food source for fish and shellfish. This also reduces 

the number of steps in the energy transfer process, enabling higher productivity 

levels. 

Components of polyculture 

Cyprinids, referred to as carps, have been the mainstay of polyculture practices all 

over the world. The feeding habits of the carps, herbivorous and detritivorous, ensure 

optimal utilization of the resources in the aquatic systems (in terms of the two food 

chains previously discussed). Asian aquaculture is dominated by carp polyculture, 

on account of the fish’s filter feeding habit, differing strata of feeding in the water 

body and compatibility with each other. Carps are grouped into three categories, 

major, medium and minor, based on growth rates. The fish attain individual sizes of 

1,000-1,500 g in a year’s time. Compatibility, mainly with regard to feeding habits, 

schooling and dwelling habits, are the key criteria for the incorporation of new 

species.

The typical South Asian polyculture employs a 

combination of major carps: 

● Silver carp (Hypophthalmichthys molitrix) largely 

filter feeds on phytoplankton with its fine gill rakers. 

● Grass carp (Ctenopharyngodon idella) grows on 

macrovegetation and sustains the growth of a 

number of other species which feed on its feces 

containing partially digested plant material. 

● Common carp (Cyprinus carpio var. communis, 

scale carp), an omnivore, is able to use a variety of 

food niches in the pond system, like decomposing 

organic matter and plankton. 

● With their different feeding habits, three Indian major carps, catla (Catla 

catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala) fit ideally into a 

polyculture system. Catla is a surface feeder, rohu dwells in the column waters 

and mrigal is a bottom feeder. 

● Silver barb (Barbodes gonionotus), Kalbasu (Labeo calbasu), Puntius 

pulchellus, Cirrhinus cirrhosa and freshwater prawns (Macrobrachium spp.) are 

also included in polyculture systems, as substitutes for some of the components 

or for adding value.

Culture systems 

Polyculture in ponds 

Polyculture technology provides a scientific basis for the optimal use of resources. 

With combinations of three Indian major carps or six species at densities ranging from 

4,000-10,000 fingerlings/ha, production levels of 2,000-10,000 kg/ha/year have been 

recorded. 

Intensification of culture practices comes in the form of supplementary feeding. This 

includes the provision of a mixture of rice bran or wheat bran and oilcake in equal 

proportions of three to five percent of fish biomass on a daily basis. Every month, the 

feeding proportion can be increased in proportion to the growth of the fish. Water 

replacement of up to 10% of the volume of the pond is another measure to 

enhance production.

Management measures 

Pond preparation in terms of clearing the pond of aquatic vegetation 

and fish predators. 

Fertilization at a rate of 10 tons cowdung or 2 tons poultry 

manure, or 5 tons of pig dung per ha per year at bimonthly 

intervals. 

Urea at a rate of 100 kg nitrogen/ha/year, i.e., 212 kg urea 

in a hectare of water in a year. 

Superphosphate at a rate of 50 kg phosphorus/ha/year, i.e., 325 kg single 

super phosphate in a hectare of water area in a year. 

Supplementary feeding of rice bran, wheat bran and oilcake. 

The practices allow a great deal of flexibility in terms of scale of operations, species, densities, 

fertilizers and feed ingredients, depending on the local resources, consumer demand of species, etc. 

Many farmers have employed two to three species like rohu and catla, feeding at frequent intervals 

and high levels of water replenishment. This has led to high levels of fish production, 10-12 

tons/ha/year, as in Andhra Pradesh, a state on the east coast of India. Fish from this region are 

supplied to several parts of India and neighboring countries like Bangladesh, Nepal and Bhutan. 

Integrated fish farming 

Integrated fish farming refers to a combination of practices, incorporating the 

recycling of wastes and resources from one farming system to the other, to optimize 

production and achieve maximal biomass harvest while maintaining eco-harmony. 

Agriculture and livestock by-products are recycled for use in fish culture systems. Fishlivestock 

farming, combined with crop raising, has been well demonstrated in 

Chinese small-scale farming systems. 

Rice-fish system, horticulture-fish farming, integration of fish farming with livestocks 

(i.e., cattle, poultry, ducks, pigs), mushroom cultivation, sericulture, etc. have not 

only allowed the recycling of organic wastes as manurial resources in aquaculture, 

but also helped greatly in environmental upkeep. 

Polyculture of carps has enabled the use of different food compartments in these 

systems, as well as through coprophagy of some of the species. A cattle head or 3-4 

pigs or 50-60 poultry birds or 20-30 ducks per 0.1 ha area of pond are suggested for 

integration with fish farming to meet the nutrient requirements of fish production 

levels of 300-600 kg in a year.

Prepared by: 

S. Ayyappan

Promoting Rice-Based Aquaculture in 

Mountainous Areas of Vietnam 

An indigenous rice-fish culture system using a local strain of common carp, Cyprinus 

carpio, was carried out in valleys in the mountainous areas of northern Vietnam. The 

self-contained, family-level system provided fish primarily for household use. Excess 

fish were dried or made into fish sauce for consumption during the dry season. 

Broodstock of the local strain of 

common carp are over-wintered in 

small ponds or cages. At the 

beginning of the rice season, they are 

taken to the rice field. Eggs are usually 

placed on branches or other structures 

placed in the field for that purpose. 

Hatching, nursing and grow-out are 

carried out in rice fields. Small 

fingerlings are stocked in rice fields at 

a density of 2000-3000 fish/ha. 

Fields are not structurally modified, 

though some have small bunded fish refuges, which are 1.5-2.0 m in diameter and 1.0 

m deep. The refuges are usually located at the center or corner of the field. Several 

openings allow frequent exchange of water and fish between the ricefield proper 

and the refuge.

The refuges serve as a cool place for 

the fish when the rice field temperature 

is high. In some places, a certain 

percentage of the fish is harvested 

earlier to avoid losses when the rainy 

season starts. 

In the early 1960s, fish farming in rice 

fields declined in areas where 

cooperatives focused on intensive rice 

production. However, this trend has 

been reversed with households 

increasingly reverting to rice-fish 

farming. Over 80% of the households in Thuanchau and Tuangiao are now growing 

fish in ponds or rice fields. 

Benefits from rice-fish culture 

The crop is profitable because both fish 

and rice are high-value products. 

Cultivating rice and fish together provides other benefits:

fish reduce pests, insects and weeds harmful to rice 

and provide additional nutrients for rice. 

The feeding activity of the fish helps to aerate the soil 

and to increase the availability of applied fertilizers. 

Designing the rice fields 

Requirements 

The design of a rice-fish field requires a suitable 

mechanism of water filling/drainage for a water 

pH of 6.5 to 7. There are two methods to check 

the acidity of water: 

A traditional method involves the use of 

betel juice. Spit betel juice into the water. If the 

betel juice remains red, the water is safe for 

fish culture. If the color turns black, it means 

that the water is acidic and unsafe for fishculture. 

Use litmus paper. If the paper turns blue, the water is safe for stocking fish. 

Field design 

Due to the 

mountainous 

topography, inlets and 

outlets should be 

created for the 

terraced plot. 

A system of trench and 

trap pond is 

recommended, which 

covers five to ten 

percent of the area of 

the plot. 

At the outlet, a fence 

is necessary to prevent

the escape of fish. 

Field upgrading 

Drain the pond 

completely after harvesting 

the last crop products. 

Fill the trench/trap pond 

with 10 to 12 kg of 

quicklime/100 sq m. If pH is 

less than 5, use 20 to 24 kg 

per 100 sq m. 

Add animal manure at 

20 kg/100 sq m. 

To drive away predaceous fish: Chop derris roots and add water. Splash the 

solution over the trench/pond on a sunny day. Leave 

the solution for three to five days 

before filling the pond. 

Stocking period 

The fingerling can be released eight to ten days after transplanting rice. Preferred 

stocking density, size and ratio of various species are recommended in the following 

table.

Transportation of fingerlings from rearing site 

The best way to transport fish is to 

use a plastic bag containing two 

thirds oxygen and one third 

water. Often, middlemen deliver 

(on motorbikes) fish seeds 

brought from the lowlands. 

Before releasing the fish, make 

sure that the water temperatures 

inside and outside the bag are balanced to reduce temperature shocks. This is 

ensured by dipping the bag into the water for 15 minutes. 

Care of the field 

In May or June, prior to harvesting the spring-summer rice crop, fish are given rice 

bran at a rate of 3-4% of its body weight. In addition, 10-12 kg of animal manure per 

100 sq m plots can also be added on a weekly basis. 

Immediately after harvesting the rice, the field should be plowed and harrowed in 

preparation for the next rice crop. 

The following should be closely monitored everyday:

● water level; 

● fish activities; 

● fence; 

● inlets and outlets; 

● rice growth; and 

● damage by pests and 

insects. 

If necessary, spray with pesticide 

as part of the Integrated Pest 

Management (IPM). To do this, 

drain the rice field gradually to 

force the fish into trenches and 

trap pond. Then, spray the rice field and leave it for six to seven days before refilling 

the rice field. 

Harvesting 

The pond is drained and a net is used to catch all the 

fish. This is done before complete harvesting. 

Harvesting is done at the end of the autumn-winter 

rice crop (November-December). 

Prepared by: 

Nguyen Huy Dien, Tran Van Quynh, Matthias Halwart and Dilip Kumar

Aquaculture in Stream-Fed Flow-Through Ponds 

Stream-fed, flow-through pond systems are a low cost and highly efficient smallscale 

aquaculture system being introduced in the upland areas of Vietnam. The 

main cultured species in this system include some herbivores: grass carp 

(Ctenopharyngodon idella) ; "bong" (Spinibarbythis denticulatus); silver carp 

(Hypophthalmichthys molitrix) and tilapia (Oreochromis niloticus). 

The system is considered semi-intensive because the water flow through ponds 

allows fish to be stocked at high densities. The circulating water flow maintains a 

good pond environment, preventing a drop in oxygen level and waste 

accumulation. As a result, the incidence of fish diseases is minimized. However, 

during the rainy season, the water supply gets turbid and contaminated with 

sediment and wastes from the catchment area. Farmers may sometimes encounter 

the problem of red spot disease in grass carp in the rainy season. 

Pond construction

Construction sites 

These areas are close to stream, 

rivulet, channels, canals and other 

places where free-flowing water 

source is available. 

Gravel, rocky or barren soil 

bottom is suitable as the pond is fed 

by flowing water. 

Pond shape 

Depends on the topography but with an area of about 50 to 1000 sq m. 

Inlet and outlet size 

Depends on pond area. 

Makes use of 10 cm (diameter) bamboo pipes connected to the water source. 

Larger ponds need 2-3 inlets to ensure adequate water flow and to provide 

daily water exchange rate of up to 1/4-1/3 of the pond volume. 

Both ends of the inlet need to be screened with a net to prevent small fish from 

escaping, and rubbish from entering the pond. Outlets are also screened to prevent 

fish from escaping. 

Pond cleaning 

Bailing and dredging of pond 

are done annually or at least 

once every two years. To ensure 

adequate water level, maintain 

the pond depth. 

Liming 

Acidic pond water 

Add 10-20 kg of quicklime/100 

sq m. 

Neutral pond water 

Apply quicklime at 7-10 kg/100 

sq m to disinfect the pond and kill wild fish.

Stocking 


2-3 fish/sq m 

Stocking rate 

Grass carp: 65% 

Mrigal:15% 

Silver carp: 5% 

Common carp: 10% 

Tilapia: 5% 

Stocking size 

Grass carp: 15 - 20 cm 

Mrigal: 8 - 10 cm 

Silver carp: 8 - 10 cm 

Common carp: 6 - 8 cm 

Tilapia: 5 - 7 cm 

Feeding and post-stocking care 

Feeding is undertaken twice a day. Feed 

quantity is estimated at 25-30% of the total 

fish body weight. Keep starch feed (1-2%) at 

one of the pond corners. Wastes and 

remains from the previous feeding should be 

removed before new feed is added. 

Daily monitoring is very important. When fish 

surfacing is observed, add water as 

necessary. Semi-intensive levels require more 

frequent supervision. 

Harvesting marketable fish 

Harvesting size 

Grass carp: 2 - 3 kg 

Mrigal: 0.4 - 0.8 kg 

Silver carp: 0.7 - 1.5 kg 

Common carp: 0.4 - 0.8 kg 

Tilapia: 0.15 - 0.25 kg 

Expected yield/year: 3 - 5 tons/ha 

Small fish could be retained for the next 

crop. Ponds need to be prepared for the 

next season.

Prepared by: 

Nguyen Huy Dien and Tran Van Quyhn

Short-Cycle Aquaculture in Seasonal Ponds 

Using seasonal ponds for aquaculture is often an overlooked opportunity. These are ponds that lose their 

water during the dry season or overflood during the rainy season. Three to six months can be adequate to 

produce a fish crop in such an environment. Care is needed not to overstock the ponds to ensure that 

there will be sufficient food for the fish to grow in such a short time. Selecting the species to be used will 

depend on local conditions and availability of seed stock and market demand. The fish carrying capacity 

of an un-enriched pond is often within 50-200 kg/ha depending on the natural fertility of the system and 

the type of fish present. 

By enhancing the natural fertility through fertilizers and organic manures, it is possible to increase carrying 

capacity to over 1000 kg/ha. To do this, the stocked fish need to be low on the food web or of mixed 

species, each taking advantage of different food niches in the pond. Fast growing fish like carps and 

tilapias are particularly suited for this sort of aquaculture. Even high value organisms such as 

Macrobrachium prawns could be considered for stocking. For short production cycles, start with mediumsized 

fish and work to get them up to premium market size in the time available. 

Even greater carrying capacities can be achieved by using supplemental or complete feeds. The higher 

the percentage of externally produced feeds, the higher the quality of the feed must be. Feeds can be 

costly so the economics -- profit on investment -- need to be watched closely. The capacity of the pond to 

assimilate organic manures or feeds without losing the dissolved oxygen during nighttime is limited so the 

pond should not be overloaded with organic enrichment. 

Good aquaculture management practices for perennial ponds also apply 

to seasonal ponds. These include security measures, control of unwanted 

pollution from erosion or harmful pesticides, removal of unwanted wild fish 

and destructive predators, and a marketing strategy. Local conditions 

should dictate what aquaculture practices to consider. The basic 

considerations are: 

● Availability of stocking material (e.g., must larger fingerlings be held over 

from the previous year to get a jump on the production season?) 

● What species and size of fish will sell well (including possible fingerlings 

from a nursery operation)

● l How can the fish be harvested? Are there value added options that could increase 

profitability (such as fee fishing, live hauling to fresh fish markets 

or making a processed product like smoked fish)? 

● l Are dikes adequate to retain water or prevent flooding? 

Ownership or use rights of seasonal ponds and the exposed dry area could be a source of conflict, 

thus, should be clarified. If the resource is of communal ownership or there is a tradition of open access, 

this could be problematic and could hinder any sort of investment for aquaculture production.

In starting such a venture, it would be useful to know the following: 

● the surface area of the pond water at stocking and the 

expected area near harvest time; 

● some things about water alkalinity (ponds with low alkalinity may 

need lime applications to help in the production of natural 

foods); and 

● the average daily temperatures during the culture period. 

Reference 

Jayasekar, A.M. 1998. Rural Aquaculture: Role and Trends. Paper 

presented at National Workshop on Aquaculture for Rural 

Development, Sarasavipaya, Colombo, Sri Lanka.

Low-Cost Aquaculture in Undrainable Homestead Ponds 

Low-cost aquaculture has been practiced extensively throughout Bangladesh and 

some eastern states of India like West Bengal, Orissa, Tripura, Assam and Bihar. It has 

been proven to be ideal for enhancing food and nutritional security and 

supplementing cash income of families. The system is based on better utilization of 

food niches available in the pond ecosystem by stocking Indian and Chinese major 

carp species with compatible feeding and dwelling habits. 

mall 

Suitable for families with the following resources 

● Pond 

Undrainable, seasonal or perennial (all year round), family owned or leased, 

homestead (up to 0.1 ha) or communal (less than a ha to a few ha) 

● Manure 

Organic manures (5-7 kg of manure/day for a 0.1 ha pond) 

– Animal excreta from family livestock like cattle dung, poultry/duck droppings 

– Farm wastes 

– Compost

– Kitchen wastes 

– Green manure using leguminous plant (dhanicha/sun pat/green gram) 

Inorganic fertilizers (200-250 g/day for a 0.1 ha pond) 

– Urea 

– Triple super phosphate 

– Muriate of potash 

● Supplementary feed 

Rice bran and deoiled cake (to limited extent) 

● Piscicide 

Any of the following: mahua oil cake, locally available materials of plant origin, 

rotenone, bleaching powder, phostoxin tablets, etc. 

● Lime 

● Fish seed 

Fingerlings of Indian and Chinese major carps, juveniles of freshwater prawn, etc. 

● Family labor 

Contributed by women, men and children 

Package of practices 

Pre-stocking management (Pond preparation) 

Eradication of weeds 

● Trim the branches of trees shading the ponds to ensure maximum penetration of 

light. 

● Remove all the submerged, rooted and floating aquatic weeds to avoid nutrient

trapping and to ensure penetration of sunlight. 

● Drain and dry the pond (once every three to four years for perennial ponds which 

retain water throughout the year). Draining is done during summer months when 

water level is low. 

● When the pond has dried, scrape off the 

upper layer of the bottom sediment and 

repair the pond dikes. The sediments 

removed can be utilized as good manure for 

crops. 

● In some cases, when the pond dries up 

(especially in case of seasonal ponds) the 

bottom is plowed and any green manuring 

agent like dhanicha (Sesbania spp.) is sown 

at 30-35 kg/ha. 

● After 30-40 days, plow the plants down and allow them to decompose in the 

rainwater which has accumulated in the pond. 

Eradication of predatory and other small fishes 

The best course is to drain and dry the pond once in two to three years. An 

alternative method is to apply any of the following locally available piscicide 

material and to remember that toxicity usually lasts for seven to 10 days. 

● Bleaching powder at 50-70 g/sq m/m depth. 

● Rotenone powder at 2-3 g/sq m/m depth. 

● Mahua oil cake (deoiled cake of the seed of mahua 

tree, Bassia latifolia) at 250 g/sq m/m depth. 

● Though aluminum phosphide (Phostoxin tablet) is not 

recommended, many farmers in Bangladesh have been seen using it at 1 tab (3 

g)/10 sq m depth. 

Liming

● Apply lime to the pond at 25 g/sq m/m soon after 

draining or after applying piscicide. 

● Increase the quantity of lime for older ponds with 

relatively thick, soft bottom sediment or soil with low pH. 

● Lime does not have to be added when bleaching 

powder is used to eradicate weed/predatory fishes. 

Bottom raking 

(Exceptions: newly dug out and sandy ponds) 

Vigorously rake the bottom of the ponds after liming by dragging a rope tied to 

stone or brick pieces. Heavy rings of burnt clay materials are also used for this 

purpose. Raking enhances the rate of the microbial decomposition process and 

release of marshy gases. 

Base manuring 

After five to seven days of liming, both organic and inorganic manures are applied 

to the pond. 

Organic manure

● Cattle dung at 100-150 g/sq m 

● Poultry/duck droppings 

● Compost at 50-75 g/sq m 

Inorganic fertilizers (any of the 

following) 

Urea at 200-250 g/100 sq m 

Triple super phosphate at 100-125 

g/100 sq m 

Muriate of potash at 50 g/10 sq m 

The desired quantities of organic and inorganic manures are mixed with adequate 

water (three times the volume of manures) and applied uniformly by sprinkling 

throughout the pond surface. 

Stocking management 

When to stock: 

One to two weeks after manuring. 

Larger fingerlings from the previous 

year’s stocks are preferred for 

better survival and quick growth. 

After rearing for three to five 

months, partial harvesting is done and the stock is replenished by restocking. 

Stocking density and combinations 

Depending upon the culture practice, two levels of stocking densities are followed: 

● When there is no possibility of providing supplementary feed on a regular basis 

keep stocking density at 5000-6000 pcs/ha.

● When farmers have the capacity to provide supplementary feed on a regular 

basis increase the stocking density to about 7000-9000 pcs/ha. 

● Stocking density may be reduced if bigger individual size is targeted for 

harvesting. Bigger size fish sells at10-20% higher price. 

The common species stocked in the ponds are combination of native and exotic 

major carps such as catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus 

mrigala), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon 

idella) and common carp (Cyprinus carpio), etc. 

Species combinations for stocking also vary depending on the 

nature of ponds (shallow or deep, newly dug out or older, 

sandy bottomed or heavily loaded with organic materials, etc.), 

local market demand and local availability of larger size 

fingerlings. The percentages of column and bottom feeders are 

generally increased in deeper and older ponds, respectively. 

Stocking of juveniles of freshwater prawn (Macrobrachium rosenbergii) with carps is 

also becoming popular. In such cases, the number of bottom feeders is reduced to 

about 5-10% and juveniles of prawns are stocked at the rate of 2500-4000 pcs/ha.

Prophylactic 

treatment 

Before stocking, 

bathe fingerlings for 

one to two minutes 

in either common 

salt (1-2% or two 

hands of full salt in 

10-12 l of water) or 

potassium 

permanganate 

solution (1-2 

teaspoon/bucket 

of 10-12 l of water). 

Post stocking management 

Fertilization 

● Mix the desired amount of organic manure 

and inorganic fertilizers with water three times 

that volume and sprinkle throughout the pond 

during bathing time (noontime). 

● Reduce or suspend fertilization if the water 

turns deep green (such incidents are common 

with old ponds with thick bottom sediment and 

community ponds surrounded by dense 

human settlement).

● For one bigha (0.133 ha) of pond 

area, which is the common size of 

homestead ponds, the farmers 

usually follow the manuring 

schedule. 

Feeding 

Supplementary feed is considered to 

be the most expensive input in pond 

aquaculture and can account for 

over 60% of the total culture cost. As 

a result, most of the farmers do not 

apply feed on a regular basis. 

However, for better yields and profits supplementary feed applied on a regular basis, 

if affordable, is helpful. 

Locally available feed materials like rice 

bran and deoiled cake of mustard, and 

other oil seeds are used in equal 

proportions and applied at the rate of 1- 

2% of the fish biomass on a daily basis. 

Depending upon the availability and 

cost considerations, some farmers use 

only rice bran. Feed is given either in 

powdered form or dough. Again, 

depending upon their availability, 

macrophytes or green leafy plants are 

used as supplementary feed for grass 

carp. 

Periodical netting is done at least once a month to check the health and growth of 

the fish and take the weight of 

individual species. Feeding rate is 

adjusted after estimating the fish 

biomass. 

Bottom raking 

Rake the pond bottom of older 

ponds with thick, organic deposits. 

This speeds up the decomposition process, releases marshy gases and aerates the 

bottom sediment. It is best to do the raking during noontime. 

Harvesting

Partial harvesting 

Some of the fish species like catla, silver carp and common carp (mirror carp) grow 

relatively faster and reach marketable size within three to four months of rearing. 

Growth is also remarkable when bigger size fingerlings are stocked (eight to 10 

months old) during warmer months (March-April). Some of the species can grow to 

about 1 kg size within four to five months and partial harvesting is carried out after 

four to five months of rearing. 

Restock immediately after harvesting to restore density. 

Final harvesting 

Final or complete harvesting is done once a year, usually 

in February to May. Harvesting is also synchronized with 

certain social and religious events when the fish price 

increases due to increased market demand.

Homestead Fish Culture: An Example from Bangladesh 

A large percentage of the Bangladesh population is poor. The poorest find 

themselves in a vicious cycle because they do not have collateral for prime incomegenerating 

activities. Many attempts have been made to break this cycle. The 

micro credit schemes operated by several non-governmental organizations (NGOs) 

are a good example of such attempts. The main idea is to give people access to 

resources with which to generate income that they can use to acquire more 

resources to generate more income. 

Instead of providing money or other means for acquiring resources to generate 

income, another approach to the poverty problem is to try to find a way to 

generate income with available resources. In Bangladesh, most poor people can 

work. They have access to labor, some land on which their shack is built, water, and 

other things the area (or fields) around their home can provide. 

An income generating activity making optimal use of these resources is homestead 

catfish culture, practiced in the project area of the Compartmentalization Pilot 

Project (CPP) in the central region of Bangladesh. This practice was taken up by the 

CPP and further refined into a homestead fish-culture program. Requirements for this 

activity are: 

food for fish;

a small pit; 

water; and 

fry 

at approximately 400 Taka (US$8). 

The concept of homestead catfish culture 

Fish food can be collected from 

the surroundings of the 

homestead (snails, bivalves, 

termites, ants, slaughter waste, 

etc). The pit does not have to be 

large: one square meter is 

enough for 50 fry and it can be 

dug by the participants 

themselves. Catfish fry is widely 

available in Bangladesh at 

reasonable prices (between 10 

to 50 Taka [US$0.2 to US$1] for 50 

pieces). After a rearing period of 

four months, 5-6 kilos of African 

catfish can be harvested, valued 

The basic concept of a homestead catfish culture program is to introduce the 

poorest people to an easy method for culturing fish in small holes or pits around the 

homestead. The African catfish (Clarias gariepinus) is used because it is known to 

take up oxygen from air, has a high growth rate and is very disease resistant. 

Experience shows that people adopt the method as soon as they are introduced to 

it. After successfully raising a first batch of fish, initiatives are undertaken for 

continuing the activity (such as contacting local fry traders or trying out different 

food sources locally available). 

Training is done on site, at the homestead. Field staff work with around 50 

participants at a time. The first step was the identification of participants. To ensure 

that the poorest of the poor received priority, a general review of the participants’ 

situations was made. To be selected for the program, potential participants had to 

meet a few criteria. 

They had to be landless (people with less then 200 sq m of land are considered 

landless in Bangladesh). 

Their general situation was poor. 

Their house had mud, bamboo or jute walls.

Potential participants who met all criteria were 

asked about their interest in the program, 

which involved their buying fry for a reduced 

price (10 Taka, US$0.20) from the field officer. 

Four basic rules for catfish culture were 

provided the participants who bought the fry: 

1. The fish should be fed every day 

(preferably until they do not want to eat 

anymore). 

2. The food can be anything, except grass 

and plastic, but the best is protein-rich 

feed. 

3. Water in the pit should be changed as 

soon as it started smelling bad. 

4. Special attention should be paid to the 

sizes of the fish (they have to be of about 

the same size range to prevent 

cannibalism) during the change of water. 

Two to three days after the sale of fry, the field 

officer visits the participants. Participants not 

visited within these three days have failed to 

rear their fish successfully. After the first two 

contacts, the household was visited every three 

to four weeks to monitor their progress and to 

answer any questions concerning fish culture. 

Season 

African catfish will grow when the water temperature is higher than 20ºC. For the 

program to succeed, a minimum water temperature needs to be guaranteed. This 

can be done by either having a growth season during the summer or ensuring a 

supply of water with a minimum temperature of 20ºC. Some of the participants 

replaced the water in their pit everyday with tube-well water (usually 21ºC).

demand is 

Environmental aspects 

In the homestead fish-culture program, the 

African catfish (Clarias gariepinus) is being 

used because of features mentioned 

earlier. These features are unique to the 

African catfish. The main reason for 

preferring the African over the local catfish 

(Clarias batrachus) is growth rate, which is 

much higher. Some reservations about the 

use of this exotic species exist: it is popularly 

believed in Bangladesh that the African 

catfish is a ferocious predator, capable of 

eating even small goats. It is feared that 

the African catfish will wipe out local fish 

populations. However, during the 

implementation of the homestead fishculture 

program in Bangladesh, no 

evidence was found concerning the 

ferociousness of this fish. On the contrary, it 

was perceived as a lazy omnivore, eating 

whatever comes in front of its mouth. 

Supply 

At present there is a thriving 

industry in Jessore (south-west 

Bangladesh) where millions of 

catfish fry are produced per 

month. This industry produces 

for (illegal) export to India, 

and for the local market. Fry 

traders all over the country 

sell the African catfish. 

Previously the demand for 

catfish fry within the project 

area was low, so the market 

for these fry traders was not 

important. 

With the homestead fish 

culture program running now,

ising and fry traders are moving in to sell their fish. The traders distribute fry to 

homesteads directly, making it possible for women to buy fry at their homesteads. 

Sustainability 

The sustainability of the program depends completely on the availability of fry of the 

species involved. As long as the fry is available, the program has an opportunity to 

succeed. 

Recommendations 

The program used a species exotic in the 

Indian sub-continent. To prevent problems 

associated with the use of exotic species, 

this method should be tried with local 

species, which should meet the following 

requirements: 

Be able to survive in anoxic water 

(water without oxygen) 

Be easy to keep, should be able 

to eat what is available around the 

homestead 

Be fast growing 

Fry should be cheap and 

available 

Species must be acceptable to 

participants and the market 

To ensure the African catfish does not contribute to serious environmental problems, 

research has to be undertaken on the ferociousness of the species before a large 

scale program is set up to spread this method. 

As the poorest people will use common resources around their homestead, an 

impact assessment has to be made on the effect of homestead fish culture on the 

environment immediately surrounding the homestead. 

Although it was not an objective, the program contributed to the improvement of 

the status of women. The method turned out to be a highly successful way to reach 

the poorest segments in the project area. The participants were highly motivated 

and very innovative. If proper research shows that there is no potential negative

impact, the method should be considered for wider use in Bangladesh and 

elsewhere.

Integrating Intensive and Semi-Intensive Culture Systems to Utilize 

Feeding Waste 

In intensive fish culture, fish are generally fed with high protein diets. The nutrient-rich wastes derived from feeding are often 

directly or indirectly released to the surrounding environment, becoming a source of pollution. The wastes from intensive fish 

culture can be used for culturing filter-feeding fish species such as Nile tilapia (Oreochromis niloticus) at low cost. Dual 

integrated culture systems, namely cage-cum-pond and pen-cum-pond culture systems, have been developed to maximize 

fish production and profitability from given inputs and to minimize the environmental impact of intensive fish culture. 

Integrated cage-cum-pond culture system 

● l It is a system in which fish species intensively cultured with high protein diets are stocked in cages suspended in ponds. 

● l The filter-feeding fish species is stocked in open water to utilize foods derived from cage wastes. 

● l Cages are suspended at least 20 cm from the bottom of small earthen ponds. This system has no water exchange and 

aeration. If provided, aerationcan increase both fish growth and nutrient recovery rates.

Extending open-pond fish culture for sometime after harvesting caged fish can further reduce 

nutrient loading in pond effluents. 

Example 1: Catfish/tilapia integrated cage-cum-pond culture 

Hybrid catfish (Clarias macrocephalus x C. gariepinus) are usually cultured intensively using high protein diets, while Nile 

tilapia (Oreochromis niloticus) are cultured semi-intensively in fertilized ponds. These two species are used in the following 

example. 

Example 2: Large/small tilapia integrated cage-cum-pond culture

Nile tilapia is commonly grown in semi-intensive ponds based on fertilizers or in integrated systems with livestock. Size at 

harvest, under such systems, usually averages 200-300g in five months. Larger Nile tilapias (around 500 g) fetch a much higher 

price than smaller ones 

(

and 2/3 for tilapia. 

Catfish are fed with commercial pelleted feed. 

In the first month, fertilize the tilapia compartments weekly using urea 

and TSP at rates of 28 kg N and 7 kg P/ha/week. 

References 

Diana, J.S., C.K. Lin and Y. Yi. 1996. Timing of Supplemental Feeding. Journal of the World Aquaculture Society 27:410-419. 

Lin, C.K. 1990. Integrated Culture of Walking Catfish (Clarias macrocephalus) and tilapia (Oreochromis niloticus). In: R. 

Hirano and I. Hanyu (eds.), The Second Asian Fisheries Forum. Asian Fisheries Society, Manila, pp. 209-212. 

Lin, C.K. and J.S. Diana. 1995. Co-culture of Catfish (Clarias macrocephalus x C. gariepinus) and Tilapia (Oreochromis 

niloticus) in Ponds. Aquatic Living Resources 8:449-454.

Yi, Y., C.K. Lin and J.S. Diana. 1996. Effects of Stocking Densities on Growth of Caged Adult Nile Tilapia (Oreochromis 

niloticus) and on Yield of Small Nile Tilapia in Open water in Earthen Ponds. Aquaculture 146:205-215. 

Yi, Y. and C.K. Lin, 2000. Integrated Cage Culture in Ponds: Concepts, Practice and Perspectives. In: I.C. Liao and C.K. Lin 

(eds.), Proceedings of the First International Symposium on Cage Aquaculture in Asia. Asian Fisheries Society, Manila, pp. 

217-224. 

Yi, Y., C.K. Lin and J.S. Diana, in press. Integrated Recycle System for Catfish and Tilapia Culture. In: Eighteenth Annual 

Technical Report. Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis.

Low-Cost Fertilization in Inland Pond Aquaculture 

The introduction and/or improvement of aquaculture in small-scale agriculture 

systems is constrained by the limited availability of on-farm resources for use in fish 

culture. However, pond fertilization, using animal manure, has long been practiced 

in many Asian countries. The general goal of pond fertilization involves: 

● increasing natural food production; 

● optimizing nutrient utilization efficiency and cost efficiency; and 

● maintaining a favorable growth environment for culture species.

Although fertilization of ponds with 

manure lowers fish production costs, 

the quality of available pond inputs 

is often poor. Intensification through 

supplementary fertilization of 

fishponds, with low-cost, off-farm 

inputs (i.e., chemical fertilizers) is one 

option to increase fish production of 

small-scale aquaculture. When 

added to fishponds, manure and 

chemical fertilizers may ultimately 

increase fish yields through soluble 

and/or particulate pathways.

Low-cost fertilization strategies for Nile tilapia grow-out 

For more than a decade, the Thailand 

Component of Pond 

Dynamics/Aquaculture Collaborative 

Research Support Program (PD/A 

CRSP) has developed various Nile 

tilapia pond culture strategies. The lowcost 

fertilization strategies include the 

use of: 

● animal manure alone; 

● chemical fertilizer alone; and 

● the combination of animal manure and chemical fertilizers. 

While the nutrient input rates and ratios are the most important factors, these 

fertilization strategies provide wide choices for small-scale farmers with various 

resources. Chicken manure (CM), urea and TSP have been chosen by PD/A CRSP as 

major sources for pond fertilization because they are widely available in many 

countries. The type of manure and chemical fertilizer is not of particular importance. 

The cost of nutrients and their availability are essential factors in selecting which 

source to choose in a particular locale. For farmers with sufficient resources, the 

selection of a strategy should be based on simple economic evaluation of the 

market prices of fish, manure and chemical fertilizers. The extended culture period of 

two to three months could result in larger fish sizes at harvest. Larger fish fetch higher 

prices resulting in an increase in net economic returns.

Pond production of Nile tilapia often utilizes manure as part of its fertilization strategy. 

As fish yields increase with greater manure rates, it becomes important to balance 

organic and inorganic nutrient inputs to reduce the threat of deoxygenation. 

Technical recommendations 

Using results from on-station and on-farm trials in Northeast Thailand, the Asian 

Institute of Technology (AIT) has developed a package of technical 

recommendations for low-cost fertilization strategies for small-scale farmers. 

Fertilization rates 

● Manure alone: types and rates of manure 

depend on availability. 

● Manure supplemented with chemical 

fertilizer: amount of chemical fertilizers is 

adjusted to the amount of applied manure 

to provide 28 kg N and 7 kg P/ha/week. The following formula is used.

● Chemical fertilizer alone: the applied amount of chemical fertilizers will provide 

28 kg N and 7 kg P/ha/week (urea at 62 kg/ha/week and TSP at 35 

kg/ha/week). The required amount of chemical fertilizers can be determined 

using the above formulae. In acid-sulfate soils, the P input level might have to 

be raised four-fold. 

Fertilization methods 

Liming 

● Manure is applied daily or weekly across the entire pond. 

● N-fertilizers are applied weekly after dissolving in water. 

● P-fertilizers are applied weekly after soaking overnight. 

● Liming is applied to maintain 

alkalinity above 50 mg/l as 

CaCO3. 

● Liming is normally done at the 

beginning when using the 

"chemical fertilizer alone" 

strategy or when the pond soil 

is acidic. 

Stocking 

● Fish should be stocked one to two weeks after pond filling. 

● Stocking density ranges from 0.5 to 3 fish/sq m (5,000 to 30,000 fish/ha), 

depending on fertilization rates. 

● It is better to nurse fry to around 5 g (6-8 cm) in hapas prior to stocking. 

Pond management 

● Water exchange and aeration are not needed. 

● Water is added weekly to compensate for loss due to evaporation and 

seepage to maintain at least 1 m water column.

Conclusion 

Low-cost fertilization strategies are suitable for small-scale farmers engaged in 

tropical pond aquaculture. Rates of manure and chemical fertilizers may be 

adjusted based on local conditions, availability of nutrients and cost. 

References 

Diana, J.S., C.K. Lin and K. Jaiyen. 1994. Supplemental Feeding of Tilapia in 

Fertilized Ponds. Journal of World Aquaculture Society. 25(4):497-506. 

Knud-Hansen, C.F. 1998. Pond Fertilization: Ecological Approach and Practical 

Applications. Pond Dynamics/Aquaculture CRSP, Oregon State University, 

Corvallis, 155 p. 

Knud-Hansen, C.F., T.R. Batterson, C.D. McNabb and K. Jaiyen. 1991. Yields of Nile 

Tilapia (Oreochromis niloticus) in Fish Ponds in Thailand Using Chicken Manure 

Supplemented with Nitrogen and Phosphorus. In: H.S. Egna, J. Bowman, and M. 

McNamara (eds.), Eighth Annual Administrative Report, Pond 

Dynamics/Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 54- 

62. 

Lin, C.K., D.R. Teichert-Coddington, B.W. Green and K.L. Veverica. 1997. 

Fertilization Regimes. In: H.Egna and C.E. Boyd (eds.), Dynamics of Pond 

Aquaculture. CRC Press, Boca Raton, pp. 73-107. 

Pant, J., S.M. Shrestha, C.K. Lin, H.Demaine and J.S. Diana. 1999. High-input Green 

Water On-farm Trials in Northeast Thailand. In: K. McElwee, D. Burke, M. Niles and 

H. Egna (eds.), Sixteenth Annual Technical Report. Pond Dynamics/Aquaculture 

CRSP, Oregon State University, Corvallis, pp. 171-181. 

Yi, Y. and C.K. Lin. 2000. Analyses of Various Inputs for Pond Culture of Nile tilapia 

(Oreochromis niloticus): Profitability and Potential Environmental Impacts. In: K. 

Fitzsimmons and J.C. Filho (eds.), Proceedings from the Fifth International 

Symposium on Tilapia Aquaculture, pp. 247-257. 

Prepared by: 

Yang Yi and C. Kwei Lin

Culture of Fish Food Organisms and Biofertilizers 

Intensification of aquaculture exerts pressure on the trophic potentials of an aquatic 

system. Fertilization and planned introduction of fish food organisms are two measures 

employed to enhance the natural productivity of a habitat. This is of great importance 

in the hatching and production stages of several fish and shellfish species. 

Fish food organisms are the different groups of plankton whose growth can be 

enhanced through the application of fertilizers. Biofertilizers are biotic agents like 

bacteria and algae that carry out functions like fixing atmospheric nitrogen. They can 

therefore substitute for chemical fertilizers. 

Fish food in ponds 

Plankton are the basic component in the food spectrum of fish in aquaculture ponds. 

Phytoplankton in freshwater ponds are blue-green algae (Cyanophyceae), green 

algae (Chlorophyceae), diatoms (Bacillariophyceae) and dinoflagellates 

(Dinophyceae). The common groups of zooplankton are protozoans, rotifers, 

cladocerans and copepods. Most fish and shellfish species used in pond culture are 

filter-feeding herbivores or detritivores, depending on the abundance of plankters. 

Culture of fish food organisms 

Fish food organisms like Chlorella, Scenedesmus, Dunaliella, Brachionus, Moina and 

Artemia are cultured as feed for hatchery systems. In-pond productivity enhancement 

measures can be undertaken, including varying proportions of organic and inorganic 

fertilizers, provision of periphytic substrates (polythene sheets and bamboo mats). The 

development of biofilm and periphyton provides additional food biomass for the fish. A 

10-15% increase in fish production can be achieved through the inclusion and 

enhancement of fish food organisms.

Culture of high-value algae like Spirulina, which commands a market price of up to 

US$25/kg, has become a secondary aquaculture industry, on the lines of ornamental 

fish culture. In India, cooperative units of Spirulina cultivation involving rural women 

have been set up. A nodal facility provides the nutrient inputs. The produce from the 

satellite marketing units are collected. Groups of 25-30 women undertake the lgal 

culture in four to six cement vats (3 m x 1.5 m x 0.6 m) using the algal starter material 

and the nutrient inputs that they receive from nodal facilities. Pure cultures are 

maintained at the central unit and are replenished whenever needed. 

Spirulina 

Spirulina (S. platensis, S. fusiformis) is a blue-green alga known for its protein level (62- 

71%). It is likewise known for its beta-carotene (1.7 g/kg), a precursor of vitamin A. It 

possesses a digestibility of 84% and net protein utilization of 61%. It is an important 

dietary component of valued fish and shellfish species like ornamental fish and prawns. 

It is also of therapeutic value to humans.

With lab-scale cultures of Spirulina obtained in 

Zarrouk’s medium (having a high level of 

bicarbonate), the commercial cultivation is 

carried out in a network of cement raceways to 

prevent algal accumulation at the surface. The 

outdoor cultivation parameters are: 

● raceways (length-breadth ratio 1.5:1) 

preferably with a mid-rib for facilitating 

water circulation; 

● culture medium depth 15-20 cm; 

● flow rate 20 cm/sec; 

● temperature 25-35oC; 

● pH 9-11; 

● hardness 120-150 mg/l; and 

● light intensity 20-30 k lux. 

Azolla as a biofertilizer in aquaculture

The significance of biological nitrogen fixing in aquatic systems has brought out the 

usefulness of biofertilization. Azolla is a floating aquatic fern, fixing atmospheric nitrogen 

through the cyanobacterium, Anabaena azollae. Its high nitrogen-fixing capacity, 

rapid multiplication and decomposition rates resulting in quick release of nutrients have 

made it an ideal nutrient input in farming systems. 

The normal doubling time 

of Azolla is three days. A 

kilo of phosphorus 

applied during its culture 

results in 4-5 kg of 

nitrogen (i.e., 1.5-2 tons of 

fresh biomass). With a dry 

weight range of 4.8-7.1% 

among different species, 

the nitrogen and carbon 

contents are 1.9-5.3% and 

41.5-45.3%, respectively. 

While Azolla is grown as a 

green manure before rice 

transplantation or as a 

dual crop in agriculture, it 

can be cultivated in earthen raceways and applied periodically to fish ponds. 

Azolla culture in earthen raceways 

The culture system comprises a network of earthen raceways (10-15 m x 1.5-2 m x 0.3 

m), with water supply and drainage facilities. The operation in each raceway consists 

of: 

● application of Azolla inoculum to cover one-third the water surface (400 g/sq m); 

● phosphatic fertilizer (3 g/sq m); 

● maintenance of 5-10 cm of water depth; and 

● harvest in a week’s time. 

The produce is about 1-1.5 kg/sq m in this period and, for continuous culture, a third of 

the biomass is left as inoculum for the next cycle. 

The suggested application rate of Azolla to meet the nutrient requirements in carp 

polyculture (and substitute for chemical nitrogenous fertilizer) is 40 tons/ha/year. This 

requires an area of about 800 sq m, a unit that could be taken up as a subsidiary 

farming activity. Along with the environmental benefits, a saving of up to 30-35% over

the traditional manuring practices is estimated. 

A related aspect is the cultivation of other duckweeds that do not fix atmospheric 

nitrogen, hence, requiring addition of both nitrogen and phosphorus as nutrient inputs. 

Different species of Spirodela, Lemna and Wolffia are candidate species, as they have 

high growth rates of 200-300 g/sq m/day. With high nutrient absorption rates, their 

doubling time is only two to three days. They are also useful in the bioremediation of 

effluents in both domestic and agro-based industries (e. g., dairy effluent) and serve as 

inputs for fish farming systems.

Feeds in Small-Scale Aquaculture 

Carp and tilapia are dominant species in freshwater fish culture in many Asian countries. Majority 

of carps and tilapias are produced by utilizing natural foods resulting from proper pond 

fertilization, often supplemented by artificial feeds to enhance fish yield and raise fish to a larger 

size than is possible with natural foods. Artificial feeds range from farm products such as grass 

and rice bran to farm-made, formulated feeds and commercial feeds. The choice of artificial 

feeds depends mainly on the cost and availability of resources to small-scale farmers. 

Types and protein contents of artificial feeds 

There are many types of artificial feeds for fish culture. The nutritional value of different artificial 

feeds depends on the palatability, digestibility and nutrient composition. The crude protein (CP) 

content (% of dry matter) of a specific feed varies because of many factors. Feed conversion 

ratio (FCR) is the wet weight (kg) of feed required to grow one kg of fish, depending upon the 

feed quality, moisture, cultured species, culture system and so on. 

A. Aquatic and terrestrial plants 

Plants are one of the most widely available fish feed sources locally. They can be used fresh or 

dried or powdered for fish feeds. 

Commonly used aquatic plants (CP 15-35%, FCR 20-100)

Commonly used terrestrial plants (CP 10-30%, FCR 20-50) 

B. Aquatic animals and terrestrial-based live feeds (CP 40-85%, FCR 10-80) 

Aquatic animal feeds and terrestrial-based live feeds are considered to be nutritionally 

complete. Terrestrial-based live feeds such as earthworms and maggots can be produced onfarm 

using various organic wastes. Some examples are: 

● mollusks such as snails and clams;

● insects such as silkworm larvae (Bombyx mori), soldier fly larvae (Hermetia illucens) and 

termites (Reticulo termes santonesis and Zootermopsia nevadensis); 

● small crustaceans such as wild small shrimp; and 

● earthworms and maggot 

C. Plant processing by-products 

The most common plant feeds from various agricultural by-products are listed below. 

Deoiled cakes and meals 

D. Animal processing by-products (CP 40-85%, FCR 1.5-4) 

Animal feeds with high nutritional values are made from a variety of sources, such as by-products 

from processing factories. Major animal protein feeds include: 

● Fish meal 

● Bone/meat meal 

● Blood meal 

● Silkworm pupae meal

● Feather meal 

● Food yeasts 

E. Industrial wastes 

Organic waste materials from industries such as food processing, wine and beer manufacturing 

and water processing are widely used directly as fish feeds or as a substrate to produce living 

organisms for fish feeds. 

F. Formulated feeds (CP 18-50%, FCR 1.5-4.0) 

Formulated feeds are composed of several materials in various proportions. The ingredients of 

formulated feeds complement each other and increase feeding efficiency. 

G. Commercial feeds (CP 18-40%, FCR 1.0-2.0) 

Commercial feeds are nutritionally complete feeds such as pellets. 

Feed preparation 

Existing techniques of on-farm feed preparation for carps and tilapias are simple. 

feeding. 

– Minced 

.Most terrestrial-based live feeds 

are added directly to fish ponds. 

.Snails and clams are crushed 

before being offered to the fish. 

.Grass and leaves are usually 

chopped when fish are small or 

ground for rearing fry and 

fingerlings or grow-out fish of both 

filtering and omnivorous species. 

On the other hand, larger fish (>50 

g) are fed directly. 

.Water lettuce, water hyacinth 

and alligator weeds must be 

treated before being used for 

– Fermented: Mix 100 kg plants with 3-4 kg rice bran and 0.5 kg yeast; seal in containers and store 

for two days at 26ºC. 

– Elimination of saponin: Alligator weed contains saponin, which is toxic to fish. The toxicity can

e eliminated by adding two to five percent table salt during fermentation. 

– Mashed: These plants can be mashed into paste, which is an appropriate feed for fish fry 

because mesophyll cells in the paste are the same size as plankton. 

● If dry ingredients are used, a well ground mixture maybe offered in feeding bags or simply 

dispersed throughout the pond. 

● A reduction in feed waste can be achieved by cooking carbohydrate sources, such as 

cassava tubers, and mixing other ingredients with the gelatinized starch. This mixture can 

either be directly fed as a wet dough or pelleted by a simple extrusion process. 

● Minerals and vitamins can be added when preparing feeds. For example, the addition of 2% 

di-calcium phosphate can increase efficiency of soy bean-based feed. It is a popular 

practice in China and India to use common salt in preparing feeds. The addition of vitamins 

can increase fish yields by 15-20% when fish stocking density is above 0.6 fish/sq m. 

● On-farm prepared pellets could be sundried and stored for future use. 

Feeding 

The required feeding rates and feed quantity for a particular fish pond depend on certain

factors. 

● Feed quality 

● Cultured species 

● Stocking density 

● Fish size 

● Nutrient inputs of manure and chemical fertilizers 

● Pond history 

Quantity can be calculated based on the expected net 

fish yield and FCR of the particular type of feed. The daily 

feeding rate is made equal to the percent increase in 

body weight of fish in the pond per day, times the existing 

biomass. In practical terms, these data are estimated 

from past years’ experiences on the increase in fish 

biomass. 

The dry matter loading rate in pond culture directly 

influences the morning dissolved oxygen concentrations 

and ammonia toxicity levels. The upper dry matter 

loading rate for short duration (three to six months) 

tilapia/carp polyculture systems is approximately 100 kg 

feed (dry matter)/ha/day. 

In well fertilized ponds, supplemental feeding is generally 

needed during the last three months to fatten fish for 

better market prices. For Nile tilapia (Oreochromis niloticus), pond culture with fertilization rates of 

28 kg N and 7 kg P/ha/week supplemental feeding is not needed before fish reach 150 g. 

Since carps and tilapia generally have relatively low market prices, a cost-effective feeding 

regime depends mainly on: 

● careful selection of feedstuff and ingredients; 

● utilization of an optimum feed formulation; 

● selection of multi-purpose equipment for feed preparation; 

● optimization of feed dispersion; and 

● minimizing feed waste. 

For small-scale farmers with poor resources, the appropriate feeding strategy is to use available 

feed as supplement in fertilized systems rather than as an ingredient for formulated feeds.

References 

Diana, J.S., C.K. Lin and Y. Yi. 1996. Timing of Supplemental Feeding for Tilapia Production. 

Journal of the World Aquaculture Society, 27(4):410-419. 

Li, S.F. and J. Mathias (eds.). 1994. Freshwater Fish Culture in China: Principles and Practice. 

Elsevier Science, Amsterdam, The Netherlands. 445 pp. 

Little, D and J. Muir. 1987. A Guide To Integrated Warm Water Aquaculture. Institute of 

Aquaculture, University of Stirling, Scotland. 238 pp. 

Yakupitiyage, A. 1992. On-farm Feed Preparation and Feeding Strategies for Carps and Tilapias. 

In: M.B. New, A.G.J. Tacon and I. Csavas (eds.), Farm-Made Aqua Feeds. Proceeding of The 

FAO/AADCP Regional Expert Consultation on Farm-Made Aqua Feeds. 14-18 December 1992, 

FAO Regional Office, Bangkok, Thailand. pp. 87-100.

Decentralized Seed Production Strategy for the 

Development of Small-Scale Aquaculture 

Good quality fish seed in the right quantity is one of the most critical inputs for aquaculture. 

Since most of the cultivable species do not breed naturally in confined water, aquaculture in 

the early days depended exclusively on seed collected from wild sources. With the 

popularization of aquaculture: 

● the demand for seed increased multifold; 

● the price of seed increased making seed collection a lucrative activity; and 

● seed collection activity reached a stage where it threatened riverine fisheries. 

Most of these issues were resolved when induced breeding was successfully demonstrated in 

Bangladesh in 1966. Taking advantage of this technology, four large regional hatcheries were 

established in the early 1980s. 

Centralized to decentralized production 

Soon, the regional hatcheries could no longer cope with the growing demand for seed. There 

were also difficulties in seed distribution to different parts of the country. To ease the situation, 

the government established over a hundred seed production farms in areas with the greatest 

potential for aquaculture. 

Emergence of mini hatcheries 

Pond aquaculture contributes over 80% of the total aquaculture production in Bangladesh. 

Except for community ponds, most of these are homestead ponds ranging from 0.05 - 0.25 ha, 

scattered throughout the country. Since the ponds are small, individual seed requirements are 

also small. Hence, long distance transport of seed was not only troublesome but also costly 

and risky. The unavailability of seed locally was a major constraint in harnessing the full 

potential of small-scale aquaculture. To address the problem, the government encouraged

farmers and rural entrepreneurs to establish low cost mini-hatcheries. At present, about 90% of 

the seeds are produced by 713 small private hatcheries, some of which are owned by NGOs. 

Government-owned hatcheries now account for only less than 5% of the total fry production. 

Most private hatcheries are small. 

The establishment of small hatcheries increased seed production. Distribution across the 

country was impressive and now, the collection of seed from natural sources has become 

negligible.

Species used for breeding in 

mini-hatcheries 

Usually major carps are widely 

cultured in Bangladesh and 

other countries of South Asia. 

Location 

Most of the mini-hatcheries are 

located in flood-free areas 

where there is a high pond 

concentration and are 

accessible by road and rail. 

Physical facilities required for a 

mini-hatchery 

A small fish hatchery is 

composed of the following: 

1. Overhead water tank capable 

of running the operation for two 

to three hours once it is filled. On 

the top of the tank, perforated 

trays are placed for water 

oxygenation. 

2. A shallow tube well is a 

minimum requirement for 

supplying water to a hatchery. A 

deep tube well is used for bigger 

hatcheries. 

3. A circular spawning/breeding 

tank 4-5 m in diameter and 1-1.25 m deep. This tank is fitted with a water inlet, outlet and egg 

collection facilities. Fishes are kept here for breeding purposes. 

4. Hatching jar, which are cone-shaped cemented structures fitted with a water supply inlet at 

the bottom. A ball is placed at the opening of the inlet line to prevent fish eggs from entering 

the water supply line. An outlet exists at the top of the jar. A fine-meshed net is warpped 

around the top of the jar to avoid losses of eggs or hatchlings. Eggs are placed in this jar at the 

rate of 2.5 liters. Capacity of the hatching jar is about 300-450 liters. The number of hatching 

jars depends upon the local demand for seed. 

5. Holding tank, a rectangular tank 3-4 m long, 1 m 

wide and 1 m deep. Broods are kept here prior to injection for spawning.

6. Shed, made of cheap material such as bamboo and straw to cover the whole structure 

(except the overhead tank) 

7. Brood fish maintained in adjacent ponds owned or leased, or collected from natural sources 

as per the production capacity of the hatchery. Usually, existing and nearby ponds are used 

as brood ponds. 

Rearing of broodstock 

Broods of major carp are maintained at a density of 2000-2500 kg/ha in the ponds. Usually 

silver carp and bighead carp are not reared along with catla to avoid food competition. 

Typically, hatchery owners maintain only about 10% of their total requirement of broods. They 

breed one female two to three times in a season. In general, the small hatchery operators 

need about 10-12 kg (combined weight) of broodstock (carps) to produce 1 kg of spawn 

(350,000 - 600,000). This includes both male and female brooders in a ratio of 2:1. 

Distribution/sale of spawn 

Farmers buy the hatchlings from a small-scale hatchery and rear them up to fingerling stage 

for sale. In most cases, they use the homestead ponds or road side seasonal ditches to rear the 

seed. Ponds used to nurse the seed are either owned or leased. Large-scale hatchery owners 

distribute their products (hatchlings) all over the country. Large hatcheries usually maintain a 

good number of nursery and rearing ponds 

and many poor people are employed in fry 

rearing. 

Hatchlings are sold at different prices 

depending on species. Catla and mrigal are 

highest and lowest priced species, 

respectively. Hatchlings are sold at rates 

ranging from US$20.00 to US$100.00/kg. Prices 

of spawn vary between peak and lean 

breeding periods: prices are high during the early part of the season and low towards the end

of the season. 

Seed production strategy for the development of smallholder 

rural aquaculture 

The strategy of decentralized seed production by 

promoting the establishment of privately-owned mini- 

hatcheries has created an immense impact on the 

development of small-scale aquaculture and culturebased 

fisheries. Fish seeds (spawn, fry and fingerlings) are 

now easily and widely available throughout the country. 

A large number of resource poor rural families depend 

on raising spawn (up to fry) and fingerlings for their 

livelihood while many others work as fish seed vendors. 

Conclusion 

Accessibility of good quality seeds at the right time and in desired quantities has also 

contributed to the development of small-scale aquaculture and enhanced fisheries. Just as 

important probably, is the employment-generating potential of these seed production 

ventures.

Small-Scale Eel Culture: Its Relevance for Rural 

Households 

The eel has always been an odd subject. Many 

people regard it as an undesirable snake-like, 

mysterious animal. However, the economic 

importance of eels to a number of countries in 

the world is undisputed, at least for Anguilla 

eels. 

Eel culture can be undertaken with a minimum 

investment, using locally available and cheap 

resources. Eels are long snake-like fish with a 

smooth, slimy, scaleless skin. There are hundreds 

of varieties of eels. Monopterus albus (rice field 

eel but in some literature also known as swamp 

eel), which disappeared locally for unknown reasons, was reintroduced by the 

International Institute of Rural Reconstruction (IIRR) in late 80s in the Philippines. Many 

farmers are raising this species for food. 

The technology described in this paper is based on several years of succesful 

practice by farmers in Indonesia, as well as on-station and on-farm trials in the 

Philippines. It has also been successfully practiced in China and Monopterus eels, 

either caught from the wild or raised, are sold for a high price (US$3-4). 

The genus Monopterus has six species and is found only in Asia. The ricefield eel (as

also the swamp eel M. cuchia) is raised in cemented tanks. The advantages of 

raising this species are: 

● it can be raised in small cemented tanks (there could be other innovations, but 

this paper deals with cemented tanks as an example); 

● it can breed in captivity without using any chemical stimuli; 

● it is an air-breathing species and can survive in oxygen-depleted conditions, and 

is, therefore, very useful in areas where water is scarce; and 

● its natural foods are fish, snails, aquatic insects, invertebrates, worms, etc. 

Methods 

Tank preparation and stocking 

1. Construct twin tanks 1 m x 2 m x 1 m in 

size with a total surface area of 4 sq m. The 

tank should be leak-proof with an outlet at 

the bottom. 

2. Layer half of the tank lengthwise. 

● The first (bottom) should be mud 

(preferably from ricefields or ponds) 

and is 10 cm thick. 

● The second is composed of straw, 

previously cured for about a week, and 10 cm thick. 

● The third consists of finely-chopped banana trunks, which are cut a week prior 

to introduction and must be 10 cm thick. 

● The fourth is cow manure, also 10 cm thick. 

● The fifth and top layer is mud placed on a slope with one end higher than the 

other.

3. Ground or spring water could be used. Water from domestic faucets can also be 

used provided the chlorine content is not very high or can be lowered by some 

mechanism (spraying or holding the water in storage tanks). 

4. Introduce water into the tank, 15 cm above the top layer, and allow the materials 

to decompose for about a week or until foam appears. 

5. Drain the water and introduce fresh water again. Repeat this process every week 

for 20-25 days until no more froth appears. 

6. Introduce tilapia or carp fingerlings to check if the tank is ready for culturing eels. 

Allow the fingerlings to stay in the tank for three days. If they do not die, that means 

the tank is ready for the introduction of eels. The tank, when ready, will have the 

same quality as a ricefield.

7. Before the introduction of eels, 

plant aquatic plants such as water 

hyacinth (Eichhornia crassipes) on the 

top soil. The plants will shelter the eels 

from direct sunlight and also act as a 

hiding place. 

8. For the tank size mentioned, 

introduce 195 to 200 eels with a ratio 

of 140 females and 60 males. 

9. The fecundity (egg-laying 

capacity) of Monopterus eels is low 

(ranging from 100-700 eggs per 

spawning), and, therefore, involves a 

very high degree of parental care. 

10. The fingerlings can either be obtained from someone who is raising them or from 

adult eels raised in your tanks. 

Feeding management 

1. Maintain proper feeding levels (3 - 6% of body 

weight/day) throughout the culture period. Feed eels with 

fish fingerlings, earthworms, snails, aquatic insects, silkworm 

pupae, slaughterhouse wastes (cow/carabao/chicken liver, 

intestine, chicken skin, etc.) 

2. Use only mud from the pond or from a well-seasoned tank for nursery pond until

the hatchlings develop into fingerlings. Fingerlings can also be raised in aquarium 

with mud from the pond bottom. 

3. Add flour or vitamin pre-mixed into the eels’ natural food with the consistency of 

stiff paste (so the food does not dissolve in water and spoil the water quality). 

4. Give food ingredients separately or in combination of two or more. A natural food, 

such as fingerlings of cheaper fish, is the most preferable. 

5. At fingerling stage, feed eels with a lot of aquatic insects, which can be produced 

naturally in stagnant water bodies. 

6. Collect golden apple snails from the rice fields to reduce the rice-eating snail 

population and feed them to the eels. 

7. Consider the following factors in feeding: 

■ size (length) of the fish; 

■ biomass (total weight); and 

■ climatic conditions, such as atmospheric temperature. 

An ideal temperature for eel to feed properly would be between 20-35ºC. 

Harvesting and transporting 

1. Harvest according to the needs of the market and the growth of eels. 

2. Harvest partially or completely. If you have more than one tank, harvest 

completely so that the next lot is ready in the new tank before harvesting. 

3. Harvest during feeding time when a net can be placed under the feed. 

4. Make sure not to injure the eels as it may, besides causing death, lower the market 

price. 

5. Starve the eels in holding tanks before transporting live to the market. 

6. Clean the tanks properly after harvest and sun-dry for a few days before stocking 

with new eels. 

Ecological implications 

Some farmers who have introduced Monopterus eels in their rice fields have noticed 

a marked reduction in snails as these are natural feed for the fish. However, some

farmers have come across the problem of dike-boring by eels, which make it difficult 

to retain water in the rice fields. The ecological implications of these species in the 

wild are being studied. Introducing the eel into the rice field will involve additional 

management efforts for the dikes. 

Eels, once introduced into the rice field , can serve as predator of golden apple 

snails, which have become a pest in some Asian countries, particularly the 

Philippines and Vietnam. 

The introduction of eels helps enhance the biodiversity value of rice fields and 

neighboring swamps. 

References 

Department of Environment and Natural Resources. 1997. Sustainable Livelihood 

Options for the Philippines: Upland Ecosystem. 

Fishery Department for the Future. 1974. FAD; Department of Fisheries – United 

Nations. 

Nasar, S.S.T. 1997. Backyard Eel Culture. International Institute of Rural 

Reconstruction, Silang, Cavite, Philippines. 

Nasar, S.S.T. 1989. Biology of the Mud-eel, Monopterus cuchia, unpublished Ph.D. 

dissertation.

Small-Scale Macrobrachium Culture in 

Bangladesh 

Farmers in the Southwestern (coastal zone) part of 

Bangladesh have developed a new method of using 

rice fields for cultivating both prawns and rice. The lowlying 

areas frequently get flooded during the monsoon 

season and the new high yielding varieties of rice are 

not appropriate. Generally, farmers are able to 

cultivate rice only during the boro season (dry season). 

During the monsoon these areas remain fallow. 

The cultivation of prawn and rice in modified rice fields 

is called "Golda Gher". Golda is the Bangla word for the 

giant freshwater prawn (Macrobrachium rosenbergii) 

while Gher refers to elevation of bundhs. This type of culture is seasonal. 

Gher construction 

● Use paddy fields located in the low-lying areas for better water holding capacity. 

● Dig canals all around the paddy field to a depth of 1.5-2 m and use the 

excavated soil for making dikes on all four sides of the field.

● Leave the middle portion of the field unexcavated. The shapes of the canal vary 

depending on the location of land and interest of the farmers. Canals should 

cover 30-40% of the area. The rest of the area should be left as is. 

● Use the canal for stocking prawns. 

● In the dry season, use the un-excavated portion for growing rice. During the 

monsoon season the entire Gher will look like a pond, while in the dry season, a 

clear distinction between rice fields and the canals can be seen. The average 

size of the gher is about 0.2 ha. 

Gher preparation 

l Fill most of the Ghers with 

rainwater. 

l Most farmers apply lime as a 

prophylactic treatment for ponds 

and to amend the soil pH at the 

rate of about 500 kg /ha. When 

Gher is dry lime it is applied 

directly but when Gher is wet 

lime it is applied to the water at the same rate of 500 kg/ha. Lime is applied all over 

the Gher.

l Fertilize Gher water with both cow 

dung at the rate of 1,250 kg/ha and 

with inorganic fertilizers, like urea and 

triple super phosphate, at the rates of 25 

kg/ha and 37.5 kg/ha, respectively. 

l When the water turns green, stock the 

Gher with prawn and fish seed. There is 

generally no exchange of water as it is a 

stagnant water culture system. 

l Maintain water’s green color through 

regular fertilization with both organic 

and inorganic fertilizers. 

Stocking 

Most of the prawn seed required for 

stocking is obtained through natural 

collection in the coastal area. There is a 

good network of people actively 

involved in organizing seed supplies to farmers. The post larvae procured from the 

wild by fishers reach the farmers through a number of intermediaries. Prawn 

hatcheries are developing slowly, with the decline in seed availability from the wild. 

The prawn post larvae are stocked at the rate of 20,000-30,000/ha, while juveniles 

are stocked at the rate of 10,000-15,0000/ha. Along with prawn seed, farmers also 

stock various species of Chinese and Indian carps, mainly for regulating water 

quality. Stocking is usually completed between May and August. Early stocking is 

preferred, but due to difficulties in obtaining seed at the right time, stocking is 

sometimes delayed by 3-4 months. 

Feeding

Farmers maintain green water by 

periodic fertilization of the pond but 

they place a heavy emphasis on 

supplemental feeding of the 

prawns. In the early years, feeding 

prawns with snail meat was 

common but now it is being 

replaced by homemade feed using 

a variety of easily available 

ingredients. Women usually 

produce these feeds and some 

have undertaken feed production 

as an income generating activity. 

Common ingredients used in feed 

preparation are fishmeal, ground 

rice, rice bran, wheat bran, 

molasses, mustard oil cake, etc. 

Farmers have developed a number 

of indigenous feed-making devices. 

Dried feed is given at the rate of 3- 

5% of the total biomass of 

prawn/fish. 

Farmers adopt broadcast as well as tray feeding. Feeding is generally done in the 

evening to facilitate nocturnal feeding habits. Adjusting the feeding rate can easily 

be done by farmers as they resort to continuous harvests at periodic intervals. Snail 

meat is still being used as feed by the farmers because of the belief that the growth 

of prawns can be improved by giving them raw meat. This belief is more common 

among wealthier farmers. 

Harvest 

Prawns are harvested several times a year and sold to local buyers. There is a good 

network of intermediaries involved in the regular collection of small harvests of 

prawns from farmers and bringing them to the processing centers. Prawns are 

harvested at least three to four times during the season and, depending on Gher 

management, harvests may reach 150-350 kg/ha. 

The sizes of the harvested prawns vary. In general, the 

average size preferred by processing factories is 60-80 g. 

Harvesting is completed by November-December and the 

small prawns are left behind and allowed to grow for 

another few months up to March-June. Small farmers sell 

the bigger prawns in March-April and buy the required

seed for stocking in May and June. 

Cultivation of rice in the elevated area (Gher) 

Use of dikes for vegetable cultivation 

Farmers utilize the dikes for the 

cultivation of different vegetables, 

with the silt removed from the canals 

serving as good fertilizer. Income from 

vegetable growing could account for 

30-40% of total income. 

When the water level can be easily maintained in the Gher, cultivation of two crops 

of paddy is undertaken: during the monsoon and dry seasons. Farmers can grow 

nearly enough rice to meet all the family’s needs. 

Profitability of the system 

The profitability of the system largely depends on the amount spent on seed and 

feed, efficient utilization of the dikes for vegetable cultivation and the size of the 

central un-excavated area for rice cultivation. In some cases, farmers have focused 

too heavily on prawns thereby increasing their risks. Alternative options are 

suggested to reduce these risks and to increase profitability. 

Using the "Golda Gher" method, farmers have been able to derive cost benefit ratios 

of up to 1:4. Such a high profitability has encouraged many small farmers to adopt 

the system. However, these small farmers get trapped in debt, especially if they do 

not get any technical advice. Emphasis is placed on understanding the ecosystem 

and developing a scheme that is appropriate to his/her economy and farming 

system. 

Constraints encountered 

● Exploitation by money lenders. Many institutions lend money to farmers, but very 

few organizations advise farmers on the wise use of credit. 

● l Unplanned expansion of ghers. Due to the profitability of the system, there is

unplanned expansion, which often blocks waterways and results in water logging. 

● l Heavy usage of snail meat. Rich farmers continue to exploit snails for prawn 

feeding and this may strain the ecosystem. 

● l Prawn seed. Almost all the seed required is currently collected from coastal 

areas. In the process of collection, seed of many other species are damaged. 

Already there are signs of a gradual decline in seed availability from the wild. 

● l Focus on prawns. Due to the high price of prawns, farmers tend to focus too 

much on prawns and invest too much on seed and feed, thereby increasing risks 

of losses and failures. 

Strategies to address these constraints 

● Farmers acquiring credit facilities are trained on financial management. 

● Credit systems that meet the needs of farmers and help them establish self-help 

groups are promoted. 

● Mass education using drama and posters to address unplanned expansion of 

ghers and to enhance the management of existing ones. An eco-village 

concept, which focuses on eliminating environmentally unfriendly practices, is 

pursued. 

● Improvement of existing cultivation practices with focus on developing feeds and 

improving feeding strategies. Farmers have used a wide variety of strategies 

appropriate to their farm. 

● Farmers are encouraged to develop systems that reduce risk and increase 

profitability through various options that are easily available. Efficient use of dikes, 

adequate emphasis on growing prawns with fish and growing more than one 

crop on paddy are some of the systems that have shown promise. 

Conclusion 

Freshwater prawn cultivation is a potential tool in the alleviation of poverty in 

Bangladesh. A good network and market structure are in place. Farmers’ produce is 

also collected, serving as a major stimulus in the development and adoption of this 

new system. There are opportunities to explore the adaptation of this farmer 

innovation in other areas, both within and outside Bangladesh.

Culture of Chinese Mitten-Handed Crabs 

Chinese mitten-handed crab (Eriocheir sinensis) is considered a delicacy in China 

and in some overseas Chinese communities. It is not a traditional species for farming, 

but its culture and culture-based resource enhancement in shallow freshwater lakes 

have become popular because of its high market value. The mitten-handed crab 

enjoys good domestic and foreign markets especially in Southeast Asia. Large crabs 

fetch a higher price than small ones. 

Although the production cost for crab 

culture is higher than that for traditional 

fish farming and crab prices have recently 

declined, in general, crab culture still 

attracts farmers. 

Though culture with seeds collected from 

the wild can be traced to three decades 

back, the success of artificial breeding in the 1980’s boosted the rapid development 

of crab farming.

Biological features 

● The natural distribution ranges from 

sub-tropical to temperate zone in 

China; 

● In the wild, Chinese mitten-handed 

crabs grow in freshwater and 

migrate to the sea in autumn to 

spawn when they reach sexual 

maturity. This normally takes about 

two years in central and eastern 

China. 

● From juvenile to marketable size 

(mature), the crab molts many 

times. Crabs grown in the same 

environment do not molt at the 

same time. Newly molted, softshelled 

crabs are vulnerable to 

other crabs especially when there is 

not enough food. 

● The mitten-handed crab is omnivorous. It exhibits a preference for food of 

animal origin over plants. It is nocturnal, thus it is more active at night in terms 

of feeding. 

● Natural habitats include freshwater lakes, swamps, irrigation canals and slow 

moving rivers, etc. Chinese mitten-handed crabs prefer clean shallow water 

with loamy or clay bottom conditions. In addition, water bodies with 

submerged aquatic plants are preferred as shelter and because of abundant 

food sources. 

Stock resources and seeds 

The Chinese mitten-handed crab has three different populations (called sub-species 

by some scholars), which are found in the south, the central and eastern regions, 

and northern China. The variety naturally occurring in the Yangtze River is 

considered the best variety for culture because of its fast growth performance and 

better market value. 

Both hatchery-produced and naturally collected larvae are available. The 

availability of natural seeds, particularly in Yangtze River, is declining under excessive 

pressure of fishing for larvae. This has given rise to the crab hatchery industry. A 

complete scientific understanding of its reproductive biology is yet to be established 

through further in-depth research to ensure more efficient and cost-effective 

production of quality seed. Crab seeds of different origins are sold for farming 

purposes or released into open waters for stock enhancement, leading to the mixing 

of stocks in the wild. There is increasing evidence of poor growth and disease

esistance of the species. Hence, there is an urgent need to regulate crab seed 

production and marketing through appropriate mechanisms such as certification, 

accreditation and licensing, similar to what has been established in the field of 

agriculture. 

Hatcheries and nursery farms grow crab larvae to "coin-size" (60-150 pcs/kg) to be 

sold to other farmers for grow-out culture. Some farmers purchase the larvae directly 

for nursing in the first year and then grow them to marketable size the following year. 

This crab culture system requires special skills because there is a high risk of failure. 

Culture methods 

The Chinese mitten-handed crabs have been cultured in pens in shallow freshwater 

lakes, earthen ponds (with fence to prevent escape), fenced renovated paddy 

fields and covered net cages. The best results were obtained from pen culture in 

shallow lakes. Growth and quality (size, appearance and fatness) in pen culture are 

impressive, probably because pens provide crabs with an environment that is close 

to their natural habitat. 

Net pen culture of crabs 

Culture of mitten-handed crabs in net pens is extensively practiced. Supplementary 

feeding is needed in addition to the natural food available in the pen. The normal 

yield is 300-450 kg/ha, but it could go as high as 900-1200 kg/ha with improved 

management skills and better levels of inputs. However, the greater yield may not 

always result in bigger crab size at harvest. 

1. Site selection 

● Preferably flat with hard 

bottom; avoid bottom 

with thick silt or mud. 

● Good water quality; pH 

7.5-8.5; dissolved oxygen 

not less than 5 mg/l; free 

from pollution; mild flow 

of water (less than 5 

cm/sec). 

● Avoid navigation 

waterway/route. 

● Water depth between 

0.8-1.5 m, without much 

water level fluctuation. 

● Abundant sub-merged 

aquatic plants

(desirable species include: Hydrilla vortilcillata, Vallisneria spiralis, Potamogeton 

crispus, etc.), snails, clams and aquatic insects, etc. 

2. Net pen design and installation 

● Size of net pen 

suitable for 

family operations 

ranges from 0.4 

to 5.0 ha, 

depending on 

the farmer’s 

available 

capital. The pen 

could be 

rectangular, oval 

or round. The 

shape does not 

matter very 

much as long 

maximum water 

exchange 

through the pen 

is ensured. 

● Bamboo stakes or small logs and ready-made polyethylene netting can be 

used for the construction of the enclosure. The mesh size is 2-3 cm. Sometimes, 

a second outer layer of pen, made of bamboo screen or net, is built to 

prevent the crabs from escaping. The distance between inner and outer layers 

is 2-4 m. 

● Bottoms of the net are sewed together to hold gravels or stones and are 

buried 20-30 cm deep in the bottom soil. Top of the net should be 0.8 – 1.0 m 

above the water, with 0.5 – 0.7 m of additional net extending horizontally from 

the top inwards to prevent crabs from escaping. The cross section of the net 

looks like an upside down "L". 

● If the water and bottom conditions are favorable, the net pen for fish culture 

can be modified for crab culture. 

3. Pen preparation and stocking 

● Before stocking, carnivorous fish, such as snakehead, mandarin fish and 

catfish, should be removed from the pen because they could prey on the 

farmed crabs. 

● Transplant aquatic plants into the pen, if there are not enough. It is 

recommended to cover at least 20% of the pen bottom area with submerged

vegetation of desirable species. 

● Fish that graze on aquatic plants like grass carp and bottom dwellers like 

common carp must be removed from the pen. Grass carp and common carp 

could disturb the growth of crabs and compete for food. Water rats in nearby 

area should be killed with appropriate methods to avoid damage to the net 

pen and to prevent them from preying on the crabs. 

● Quicklime dissolved in water should be applied by broadcasting it in the pen 

to disinfect the culture area. 

● Crab seeds with 6-15 g/pc or 65–150 pc/kg size are desirable. The 

recommended stocking density is 60-150 kg/ha. The pen could be stocked 

starting from February to April as usually practiced in China. 

● Some filter feeder fish like the silver and bighead carp could be stocked in the 

pen as bring-along species for culture. They help clean the water in the pen. 

4. Routine management 

● Supplementary feeds include aquatic plants collected from outside, 

vegetables, squash, sweet potatoes, boiled corn and wheat, etc. 

● Animal feeds include crushed snails and clams, trash fish, slaughterhouse 

waste, and silkworm pupae, etc. 

● Feeds are added to the pen twice a day (early morning and in the evening). 

The feeding rate is 3-6% of the body weight per day. About 30-40% of the daily 

ration is given in the morning and 60-70% in the evening. Animal protein feeds 

should account for 50-60% of total feed. 

● Daily removal of leftover feeds (particularly in the morning) is important to 

keep the pen area clean. 

● Daily check of the enclosure is recommended to ensure that damage to the 

net is repaired immediately. 

● Broadcast 8-10 kg/ha of quicklime every three weeks. 

● For large pens, if aquatic plants grow too much, some plants should be cut in 

a row (1 m wide) parallel to the water current to allow faster water exchange 

in the pen. 

5. Disease prevention and control 

● Preventive measures are more effective. A clean culture environment helps 

reduce the risk of diseases. 

● Diseases constitute a major threat to the success of culture. In 1998, the 

outbreak of "shivering disease" (common term, not well defined so far) caused 

US$120 M worth of losses to crab farmers nationwide. 

● Basic research is lagging behind but chemicals and drugs have been 

developed based on preliminary research work and been commercially 

produced. 

● Certain chemicals such as malachite green, copper sulfate, zinc sulfate, etc., 

commonly used for fish disease control or treatment are not suitable for crabs 

(different toxicology).

6. Harvest and conditioning 

● The crabs are harvested when they reach maturity and are ready to migrate 

to the sea in mid-September to mid-October, when temperature drops to 

12ºC. Crab traps and gillnet are used for harvest. 

● Crabs are kept in holding tanks or cage before marketing. Feeding of the 

crabs in holding tanks should continue for fattening purposes. Holding of the 

crab also allows the farmers to wait for a better price before selling the 

product. 

● Crabs must be kept alive until it reaches the consumer’s kitchen. Dead crabs 

have no market value at all. 

Conclusion 

Crab farming is a relatively simple aquaculture practice, suitable for both large and 

small scale operations. At present, the seed of crabs is still expensive and quality of 

seeds not consistent through years. Further development in hatchery technology 

and nursing techniques will help to reduce the production cost by providing 

cheaper seeds in the future. 

Prepared by: 

Zhou Xiaowei

Aquaculture and Sewage Water Treatment 

Growing population and the lack of a corresponding infrastructure for waste water 

treatment are growing concerns. In every country, the generation of domestic 

sewage escalates, often beyond the capabilities of conventional sewage treatment 

plants, which include oxidation/waste stabilization pond, activated sludge, trickling 

filter, aerated lagoons, upflow anaerobic sludge blanket process, etc. At the same 

time, it is increasingly being recognized that sewage is not just a pollutant, but rather 

a nutrient resource. Traditional practices of recycling sewage through agriculture, 

horticulture and aquaculture have been tried in several countries. This article 

discusses the role of aquaculture-related approaches for processing sewage water. 

Sewage is a dark colored, foulsmelling 

fluid containing organic 

and inorganic solids in dissolved 

and suspended forms. It contains 

90 to 99% water, 10-70 mg/l 

nitrogen, 7-20 mg/l phosphorus, 

12-30 mg/l potassium.

Normal management practices 

Sewage-fed culture 

Several variations from overhung latrines over the 

ponds to the application of primary treated sewage 

into fish ponds exist. The sewage-fed fish culture in 

Munich, Germany and sewage-fed bheries of West 

Bengal, an Eastern State of India, have been 

extensively studied. The practices in over 5,700 ha 

area in Bengal produce over 7,000 tons of fish 

annually. 

■ Fry stocking: 30-50 mm 

■ Fish density: 40,000 – 50,000/ha 

■ Sewage application: weekly or bimonthly intervals 

■ Field indices for pond’s sewage intake: algal blooms, fish surfacing, dark color 

of water 

■ Production rate: 3-7 tons/ha/year 

Carp polyculture is practiced in most of these waters 

Silver carp (Hypophthalmichthys molitrix) 

Common carp (Cyprinus carpio var. communis) 

Indian major carps – Catla (Catla catla), Rohu (Labeo rohita) and 

Mrigal (Cirrhinus mrigala) 

Other medium and minor carps 

Bata (Labeo bata) 

Reba (Cirrhinus reba) 

Mola (Amblypharyngodon mola) are often used as components of 

fish culture in these waters

Problems related to sewage-fed culture systems 

Accumulation of silt and high organic matter at pond bottom 

Incidence of parasites and fish diseases 

Possibilities of pathogens being transferred to humans 

Solutions 

Regulate sewage intake into the ponds 

Provide freshwater for dilution 

Use of prophylactics 

Depuration of fish in freshwater before marketing 

Several modifications in the system are also being suggested to achieve 

greater efficiency and sustainability. 

Sewage treatment through aquaculture 

Resource recovery from wastewater is important not 

only for realizing the nutrients as food, but also in 

ensuring that they do not contribute to the 

eutrophication of natural waters that are the usual 

receptors. 

Biological treatment of sewage using algal-bacterial 

associations, macrophytes and fish employ both 

autotrophic and heterotrophic food chains, rendering 

the effluent nutrient-deficient and less harmful to the 

environment into which it is discharged. 

Ponds serve as facultative receptacles for sewage treatment, and also provide 

oxygen input from the photosynthesizing algae and macrophytes. Ponding reduces 

the bacterial loads by two to three log units and bacteriophage loads by three to 

four log units even at the loading rates of 100 kg COD (chemical oxygen 

demand)/ha/day. 

Aquaculture-based sewage treatment plant (ASTP) 

An aquaculture-based sewage treatment plant designed in India has incorporated 

cultivation of duckweeds prior to application of fish ponds and post-fish culture 

depuration, with the objectives of refinement of sewage-fed fish culture and sewage 

treatment through aquaculture practices. 

The ASTP consists of a set of duckweed ponds, fish ponds and depuration ponds, 

located at a place 250 m away from the residential area and borewells. 

Gravitational flow of sewage wherever feasible for sewage intake into the treatment

complex will be advantageous. 

Design and construction of a model to treat 1 mld sewage 

A model for treating one million liters per day (mld) of sewage, from a population of 

about 20,000 is described below: 

Source: A receiving chamber for sewage feeds the effluent to the ASTP. 

Duckweed culture complex: It comprises 18 ponds with brick lining (25 m x 8 m x 1 

m), with three series of six ponds in a row. The sewage is retained here for a period of 

two days, with free passage between the series. 

Fish ponds: Two fish ponds (50 m x 20 m x 2 m) receive the treated sewage from the 

duckweed ponds and retain it for three days. 

Depuration ponds: Two depuration ponds (40 m x 20 m x 2 m) with freshwater, also 

used as marketing ponds, provide for depuration of fish for a week before 

marketing. As the fish harvest is occasional, these ponds are also used for the culture 

of grass carp, fed with duckweeds from the system. 

Outlet: Sewage outlet drains are provided from the fish and depuration ponds for 

drainage into natural waters.

Duckweed culture 

Duckweeds serve as nutrient pumps, reducing 

eutrophication effects and providing oxygen through 

the photosynthesis activity. 

The ponds are inoculated with duckweeds to cover 

roughly one-third of the surface area (400 g/sq m). The 

approximate growth rates of individual weeds in the 

sewage-fed culture system are Spirodela 350 g/sq 

m/day, Wolffia 280 g/sq m/day, Lemna 275 g/sq m/day 

and Azolla 160 g/sq m/day. The harvested weeds could 

be used to feed grass carp in the marketing ponds or 

composted for application in fish ponds and horticulture 

fields. 

Fish culture 

The ponds are stocked with Indian and Chinese carps at 

a density of 10 000 fingerlings/ha (Catla 40%, Rohu 40% 

and Silver carp 20%). Grass carp, Ctenopharyngodon 

idella, is stocked in the marketing pond and fed with 

duckweeds harvested from duckweed ponds. The fish 

stocks are checked at monthly intervals for their health 

and growth through sample nettings. By monitoring of 

dissolved oxygen levels to maintain 3-5 mg/l, the sewage flow is regulated. Fish 

harvest is carried out 8-12 months after stocking, with mean individual sizes in the 

range of 600–800 g. About 600-700 kg of fish are harvested from the two fish ponds, 

working out to a production level of 3-3.5 tons/ha/year and about 400 kg of fish are 

harvested from the marketing ponds, representing considerable economic returns 

from the sewage.

Depending on the area of operation, different 

fish species could be used. Tilapia (Oreochromis 

spp.) and Mandarin fish (Siniperca chautsi) are 

some of the species that are cultured in sewagefed 

waters in China and other countries. 

The ASTP provides for retention of sewage for 

two days in duckweed ponds and three days in 

fish ponds. This achieves the desired reduction 

in nutrient concentrations, BOD, COD and the 

bacterial populations to meet the standards for 

discharge into natural waters. The fish produced 

from the system enables recovery of about 40% 

of the working costs. 

This model has been used in several Indian 

villages for community sanitation and 

aquaculture, with modifications. Typically, a 

third of the pond of the size of 0.2–0.4 ha at the 

inlet end serves as the receptor of sewage from 

solid wastes from community latrines. This 

portion is stocked with duckweeds that multiply 

in the presence of organic matter and effluents 

that then pass into the adjacent portion of the 

pond stocked with fish. With a continuous flow, 

the organic loading is regulated in different 

seasons.

Prepared by: 

S. Ayyapan

Water Quality Management for Freshwater Fish 

Culture 

The aquatic environment governs fish life, hence, water quality should be suitable for 

fish culture. When environmental conditions do not conform to the optimal range for 

normal fish growth, then fish culture could be affected. The major concerns of fish 

culturist should be to deal with the aspects of water quality that may cause poor 

growth or death of fish. Water quality management aims to regulate environmental 

conditions so that they are within a desirable range for growth and survival of fish.

on fish 

Temperature 

The aquatic environment is composed of many 

variables. Fish culturists must know the variables that 

are potential sources of stress for the fish. The variables 

may also explain the causes of fish culture problems. 

Although, these parameters can be analyzed using 

standard laboratory procedures and apparatuses or 

water quality analysis kits, there are practical 

indications when these parameters become risky to 

the fish. 

Water quality variables and their effects 

Fish are cold-blooded and dependent upon the water temperature in which they 

live. Every fish species has an ideal temperature range within which it grows quickly.

Dissolved oxygen (DO) 

The concentration of DO in natural 

water is influenced by the relative rates 

of diffusion to and from the atmosphere, 

photosynthesis by aquatic plants and 

respiration by the entire aquatic 

biological community. Oxygen is the 

most common limiting factor to fish life. 

Aquatic fish species breathe best when 

DO concentrations are near saturation. 

As DO concentrations decrease, fish are 

stressed and their immune function may 

be compromised. DO concentration of 

5 mg/l or greater should be maintained 

for normal fish culture. 

Common water quality problems and corresponding 

management techniques 

Low-alkalinity water and acid sediments 

Liming can often solve problems with acid-base relationships in fishponds. Waters 

with alkalinity of less than 25 mg/l often need liming. Application of liming materials is 

not a type of fertilization. Liming may be best viewed as a remedial procedure, 

necessary in some ponds to permit the normal responses of fish population to 

fertilization and other management procedures. 

Finely grounded limestone (

Liming rates 

Application rates for lime are based 

on the efficiency rating of the liming 

material and its neutralizing value. 

Lime requirement of bottom mud 

can also be based on pH and 

texture of mud. 

Liming methods 

1. Broadcasting / spreading 

at pond surface 

2. Soil incorporation 

3. Pump system – for 

hydrated lime 

4. Platform spreading 

5. Piling along shallow 

water edges of ponds and 

distributed by wind action 

Effects of liming 

Desirable effects 

● High pH in mud and water stimulates microbial activity and rates of organic 

matter and nutrient recycling increase. 

● Total alkalinity increases after liming because of greater concentration of 

bicarbonate, carbonate and hydroxide. An increase in total alkalinity, caused 

mostly by bicarbonate, results in increased concentration of CO2 which is 

available for plant use. 

● Fish food organisms increase. 

● Production of benthic organisms increases. 

In ponds with low concentrations of organic matter, the addition of readily 

decomposable organic matter during the liming application will hasten the 

dissolution of liming materials and the stabilization of water quality. The precipitation 

of colloidal materials in the water (following liming) may produce turbidity and

encourage the growth of underwater weeds. 

Undesirable effects 

● The immediate insolubility of descending lime may cause phosphorous to 

react with sinking lime. As a result, P is lost from the solution. 

● Appreciable levels of CO2 cannot exist in the water when pH rises. 

Turbidity 

Turbidity is a term that refers to the suspended dirt and other particles in water. Two 

sources of water turbidity are clay particles and plankton. Clay turbidity (abiotic) 

usually imparts brown color into the water while plankton turbidity (biotic) gives 

green/yellow green/brownish/yellow green color. 

l Clay turbidity 

Clay turbidity may come from surface runoff and the disturbance of sediments by 

bottom-feeding fishes. This type of turbidity can be a problem, especially in shallow 

ponds. The dirt and particles prevent sunlight from reaching the plankton limiting 

their capacity to produce oxygen. Moreover, clay particles can block fish gills, 

hampering respiration. 

l Measures to control clay turbidity 

Bales of hay may be scattered to clear up the water surface. The hay will help settle 

the mud particles. They can be removed easily from the pond edges. However, the 

method should not be used in hot weather because the hay will decay very quickly 

and will begin to use up oxygen in water. This method applies only to small ponds. 

Organic manure at the rate of 2,440 kg/ha can also be used to control clay turbidity.

Plankton turbidity as an index of 

natural food productivity of the 

pond 

Plankton turbidity is measured using a device 

called Secchi disc. When the disc goes into 

the water, it will sink straight down and 

disappear from sight at some depth. If the disc 

disappears at 30 cm depth, the pond 

contains enough natural food (mainly 

phytoplankton). Secchi disc visibility (SDV) 

depth of more than 30 cm is an indicator that 

there is not enough natural food and that the 

pond needs fertilization. 

Productive tilapia ponds usually has a 

SDV depth between 10 to 30 cm. If 

SDV depth is less than 10 cm, this 

means that there is too much 

phytoplankton in the pond and there is 

a good chance of a die-off that may 

lead to DO depletion. 

Turbidity can also be measured 

without a disc, but this requires 

experience. The farmer stands in the 

pond and sticks his arm under the 

water. If his hand disappears then the 

water is not too turbid. If the arm disappears before the water reaches the elbow, 

the water is either turbid or very productive. If the entire arm -- from hand to shoulder 

-- can be seen, then the water is not too turbid nor it is very productive in 

phytoplankton. High biotic turbidity (phytoplankton) is an indication of very fertile 

water that is highly conducive to DO depletion due to high phytoplankton 

respiration rates and die-off. 

Poor dissolved oxygen 

Once the DO drops to a dangerously low level, fish show signs of distress. When fish 

are seen gasping for air at the surface of the water, particularly in the morning, it is 

an indication of low DO concentration in the pond. 

One of the techniques to prevent DO depletion is by aeration or circulation of pond 

water. By employing aeration in intensive fish culture, production can be markedly 

increased. The economics, however, of employing aeration in fishponds should be

considered. Some of the emergency techniques are flushing and mechanical 

aeration. 

Gas toxicity (Nitrogen and H 

2S) 

Aeration of water tends to dissipate toxic gases from the water into the atmosphere. 

Another management technique is to allow new water to flow into the pond in order 

to dilute the "old" water containing the toxic gases. 

Prepared by: 

Arsenia G. Cagauan


Lake and Reservoir-Based 

Systems 

Pen Fish Culture in Shallow 

Freshwater Lakes 

Pen and Cage Culture in 

Philippine Lakes 

Integrated Development of 

Floodplain Wetlands in India 

Freshwater Cage Culture of 

Chinese Carps 

Low-Cost Cage Culture in 

Upland Areas of Vietnam 

Lake and Reservoir-Based Systems

Pen Fish Culture in Shallow Freshwater Lakes 

Shallow freshwater lakes are a very important resource in China. Since the mid-80s, 

development of fisheries in shallow freshwater lakes has attracted the interest of the 

government. Different kinds of resource enhancement and aquaculture approaches 

and techniques were tested and adopted in different types of shallow freshwater 

lakes, aimed at improving the income levels of fishermen and rural communities 

around the lakes. 

Although effective increases in fish production through the protection of natural fish 

resources and stocking of artificially produced seeds in many inland lakes can be 

achieved, such approaches depend entirely on natural productivity. The fish yield is 

often influenced by managerial factors, especially the ability to control fishing 

activities in the water bodies. Moreover, these approaches become much less 

effective in larger natural water bodies.

However, pen fish culture, introduced 

to inland freshwater lakes in China two 

decades ago, has proven to be a 

very effective way of growing more 

fish in large shallow freshwater lakes. It 

is suitable for both large and familyscale 

operations. In Jiangsu province, 

where pen fish first started in China, 

fish pen area has exceeded 10,000 ha 

in 1999. 

Culture technology 

Compared with other aquaculture 

systems, pen fish culture involves the 

use of simple technologies. The major technical aspects are discussed below. 

Site selection 

Selection of site for fish pen installation significantly affects the output of the 

operation. Among the most important factors for consideration are: 

● appropriate water depth (3-5 m); 

● relatively stable water level, mild current is desirable; and 

● bottom with little silt and absence of emergent aquatic weeds/plants are 

favorable for constructing fish pen. 

Setting up fish pen 

A fish pen’s function is to keep the fish in a confined area to facilitate feeding and 

other management operations. Suitable sizes of fish pens for single-family operations 

are 0.3-0.5 ha. 

Bamboo and polyethylene netting 

are common materials used in 

building a fish pen. Ready-made 

netting or bamboo screen is fixed 

to the bamboo posts driven 0.5-1 

m deep into the bottom soil to 

form a circular or rectangular 

enclosure. The mesh size of the net 

or bamboo screen should be small 

enough to prevent fish from 

escaping.

Round fish pens use less materials per unit area. 

The top of the fish pen should be 0.5-1 m above the expected maximum water level. 

The bottom should be buried 20-30 cm into the soil using a weight or sinker 

(stone/gravel bag or iron chain sewed to the bottom of the net or screen) to prevent 

fish from escaping beneath the net or screen. The pen enclosure should have a gate 

to allow the boat to go in and out the pen for production operations. 

Suitable fish species and stocking 

Polyculture is commonly 

practiced in fish pens. 

Herbivores, such as grass carp 

(Ctenopharyngodon idella) and 

blunt snout bream 

(Megalobrama 

amblyocephalia); omnivores, 

such as common carp (Cyprinus 

carpio) and crucian carp 

(Carassius auratus); and filter 

feeders, such as silver carp 

(Hypophthalmichthys molitrix) 

and bighead carp (Aristichthys 

nobilis) can be cultured within 

one fish pen. However, the species composition should be carefully determined 

depending on the availability of natural food. On the average, herbivorous fish 

account for 60-80%; omnivores, 20-30% and filter feeders, 10-20% of the total stocking 

weight. 

Recently, species of higher value like mandarin fish, Chinese mitten-handed crab, 

giant freshwater prawn (Macrobrachium rosenbergii) and local freshwater prawn (M. 

nipponensis) have become important species for culture in pen in some areas. The 

economic return is significantly higher, although it also involves higher cost in seed or 

feed, or both. 

To achieve high survival rates and greater fish weight during the culture period, large 

size fingerlings are recommended for stocking in pens. The stocking size is normally 25- 

250 g depending on the species. On the average, fish stocked in pens gain five to 

ten times their body weight during the eight to ten months of culture period. The 

body weight gain is mainly affected by temperature and availability of feed. 

The stocking time depends on the supply of seeds so it is advisable to stock early, 

whenever fish seeds are available. 

Feeding

Day-to-day regular feeding is very 

important to ensure good fish 

growth. A feeding frame (for 

floating feeds such as weeds and 

grasses) and a submerged feeding 

tray (for artificial feeds such as 

hard pellets) should be installed in 

the pen. It allows the farmers to 

monitor the feeding of fish and 

remove leftover feeds. 

Farmers are advised to use locally 

available natural food to reduce production costs. They are encouraged to collect 

aquatic weeds and mollusk from the same water body to feed the fish inside the 

pen. When artificial feeds are used, farmers are encouraged to acquire a small pellet 

formation machine to make farm-made hard pellets with oil cakes, wheat bran and 

rice bran and other locally available raw ingredients. Pellet feed causes less pollution 

to the water because of reduced loss of feed when compared with the direct use of 

these raw materials. 

The quantity of feed should be adjusted according to the temperature and weather, 

and increased according to the growth of the fish. During good weather and under 

high temperatures, more feed should be added. 

Harvesting 

Several types of fishing gears are used for harvesting in the pen. Gill and casting nets 

are used in partial or selective harvesting during the culture period. In addition, 

seining is carried out for total harvest by the end of the production season. 

Production and economic return 

Seeds and feeds account for the largest proportion of production cost in pen culture. 

In large-scale production, fish production ranges from 3,000 to 10,000 kg/ha. The 

annual economic return from pen culture ranges from US$ 1,500 to 3,000/ha. 

Pen fish culture in Gehu Lake: A Case Study 

Gehu Lake is a typical shallow freshwater lake with abundant aquatic weeds. It is 

located in Jiangsu Province in the lower reach of the Yangtze River. The water 

surface area of the lake is approximately 16,400 ha. An integrated approach 

involving pen culture, protection of natural fishery resources and conservation of

environment has been carried out since 1991. Pen culture has played a major role in 

achieving higher fish production from the lake. 

Pen fish culture in Gehu Lake 

employed two major stocking 

models. In the first model 

both blunt snout bream and 

grass carp were used as 

major species, whereas 

Chinese bream is the only 

major species in the second 

model. Stocking of filter 

feeders in fish pens is 

relatively low because the whole lake already has silver and bighead carp in the 

open area. 

Favorable environmental conditions has made the practice of pen culture in Gehu 

Lake very successful. The rich aquatic weeds ensure good water quality and food 

source. The culture models used are suitable for the environmental conditions and 

natural resources of the lake. [Herbivorous fish -- grass carp and Chinese bream -- are 

the major culture species.] 

Constraints and concerns for future development

Despite the advantages of pen culture in shallow freshwater lakes, there are several 

constraints and concerns that should be taken into account in future development. 

● Pen fish culture is operated in natural open water. It is, therefore, susceptible to 

some natural hazards such as floods and typhoon that might cause serious 

damage to the fish pen and financial losses. Good site selection and close 

supervision can help minimize the possibility of such damage. 

● Poor planning and management of culture operations can damage the 

natural environment and affect the other important functions of the lake. To 

avoid such adverse impacts, natural food from the lake should be used. When 

commercial feed is used, the quality and quantity should be well controlled to 

minimize pollution caused by feed wastes. 

● There should be a very strict control on the expansion of pen culture area 

according to the type and character of the lake. 

● Farmers around the lake do not have the same access to lakes compared to 

fishpen holders. Measures should be taken to minimize or avoid conflicts 

between farmers involved in pen culture and those who are not. 

References 

Jianren, Zhang. 1997. Study on Pen Fish Culture Techniques Combining High Yield 

and Efficiency with Good Quality in Gehu Lake. Collection of papers on high 

yielding fisheries models and ecological fisheries studies, Press of Agriculture, 

Beijing, p. 225-230. 

Ministry of Agriculture. 1997. China Agricultural Yearbook, 418. 

Renkui, Cai. 1991. Development History of Freshwater Aquaculture Technology in 

China. Press of Science and Technology, Beijing. 

Weiliang, Shi. 1993. Fish Enhancement and Aquaculture in Inland Open Waters. 

Dalian Fisheries University. 

Xingji, Xu. 1997. Study on Integrated Techniques of Pen Fish Culture Aimed at High 

Yield and Efficiency with Good Quality in Gehu Lake. Collection of papers on high 

yielding fisheries models and ecological fisheries studies, Press of Agriculture, 

Beijing, p. 203-213. 

Prepared by: 

Miao Weimin

Pen and Cage Culture in Philippine Lakes 

Pen and cage culture systems have existed for nearly three decades, both on 

commercial and small scale, in Philippine lakes particularly in Laguna de Bay and in 

the seven crater lakes in San Pablo City. Likewise, Taal Lake has attracted investors in 

cage farming. Milkfish (bangus) is the most popular species for pens, while Nile tilapia 

is most preferred species for monoculture in cages. This article discusses two cases 

and the lessons learned from these two sites. 

Laguna de Bay 

Laguna de Bay is a shallow (3.0 m), 90,000-ha lake, the largest in the Philippines. The 

overall responsibilility for water resources management of the lake belongs to the 

Laguna Lake Development Authority (LLDA). In 1970, LLDA initiated fishpen culture 

that proved that milkfish production could be sustained with the use of natural food 

(phytoplankton), which was seasonally abundant in the lake, and that fish yield 

could be increased 3.5 times over that in open water, a potential profitable 

enterprise for poor lakeshore families. LLDA offered the fishpen technology to the 

fishermen under a cooperative scheme but it was not readily accepted because of 

initial capital constraints and satisfaction with the open water catch i.e., goby 

(Glossogobius giurus), perch (Therapon plumbeus), carp (Cyprinus carpio) and 

catfish (Arius manilensis, Clarias macrocephalus and Clarias batrachus), reaching 

80,000-82,000 tons in 1961-1964. This prompted businessmen, politicians, and even

anking military officers to go into fishpen culture which then spread rapidly. Fishpen 

operators became a potent and very influential bloc. Under LLDA regulation, no 

corporation could have more than 50 ha of fishpen concession. However, influential 

investors managed to circumvent the regulation by putting up interlocking 

corporations actually controlled by the same people. The chaos was aggravated by 

fishpen permits issued by municipal mayors of lakeshore municipalities without 

coordination with or reference to LLDA's zoning or master plan. From 5,000 ha in 

1973, fishpen area expanded to 31,000 ha in 1982. Stocking density ranged from 

25,000 to 100,000 milkfish fingerlings/ha.

The proliferation of fishpens 

resulted in socio-economic 

problems affecting both pen 

operators and marginal 

fisherfolk. Milkfish rearing period 

was stretched to 8-15 months. 

The annual yield dropped from 4 

t/ha in 1973 to 2 t/ha in 1982. 

Moreover, the fishpen 

production was 62,000 tons and, 

from the remaining two-thirds of 

the lake open to the small 

fishermen,19,000 t for a total 

yield of 81,000 t. This was clearly 

equivalent to the yearly catch in 1961-1964 when there were no fishpens in the lake. 

To the environmentalists, fishpen did not contribute to the total finfish production of 

the lake. The reduced catch not only prejudiced the more than 15,000 families of 

small fishermen, but also affected those engaged in snail collection and duckraising. 

Congestion of fish pens blocked the movement of water hyacinth 

(Eichhornia crassipes) in navigational lanes, hindering the movement of fishing and 

commercial boats. Access to open waters became difficult for the small fishermen, 

who were accused of poaching. As a result, confrontations between the poor 

fisherfolk and the affluent pen operators were reported. 

To assist the fisherfolk, a project funded by the Asian Development Bank, the 

Organization of Petroleum Exporting Countries (OPEC) and the government was 

launched through LLDA in 1988. The project extended sub-loans to 1,550 poor 

fishermen for the development of 550 fish pen modules covering 2,500 ha. The 

project, however, failed because of the long grow-out period for fish resulting from 

the lake's declining productivity. The typhoons also wiped out many fish pen 

modules shortly after completion. Overall, poor fishermen have not benefited yet but 

the loans must be repaid. 


1. Proper management and political will 

The conflict of jurisdiction over the lake between the lakeshore municipalities and 

LLDA was resolved by the Supreme Court in favor of LLDA. In 1996, a new master 

plan for a fish pen belt was approved by former President Fidel Ramos, which 

effectively reduced the area for pens to 10,000 ha and provided more open area 

for fishermen. Fish pens outside the belt were demolished or relocated. Under the

new administration, the implementation of the fishpen belt has yet to be evaluated. 

2. The carrying capacity of lakes should be 

considered in 

aquaculture planning 

One of the mistakes in the past was to attribute fish 

yields (tons per hectare) to the water areas covered 

by the pens and cages. It was not taken into 

account that water circulates in and out of fish pen 

and, hence, fish production was a result of a wider 

feeding area beyond the enclosures In a 1991 

evaluation, a hectare of fishpen stocked with 60,000 

milkfish fingerlings required a food supply area of about 12 ha. Therefore, the 

reported yield of 4 t/ha actually meant 4 t/12 ha of lake area. Adding more fishpens, 

therefore, meant exceeding the carrying capacity of the lake. 

3. Stakeholders’ awareness of the ecological events of the lake is important 

Laguna de Bay undergoes two important limnological behaviors, which affect 

fisheries. First, is the regular occurrence of high turbidity due to strong winds and 

second, seawater intrusion when lake level recedes to the average low level of 

Manila Bay. As a consequence of high turbidity, the phytoplankton becomes scarce 

but as sea water backflows to the lake, settling of suspended matter and clearing 

followed. Phytoplankton production is stimulated and the lake turns green in color 

with algal bloom formation – an abundance of natural food welcomed by pen and 

cage operators and fishermen. The government, however, began pursuing the use 

of Laguna de Bay as source of domestic water supply in the new millenium. The 

back flow of sea water had to be prevented through the operation of a hydraulic 

structure endangering the food web of the lake. Strong opposition from the fishery 

sector forced the government to study other options to preserve the multipurpose 

use of the lake. 

Sampaloc Lake 

Sampaloc Lake is 104 ha, the largest of the seven crater lakes of San Pablo City. Due 

to an average depth of 20 m, the lake exhibits thermal layering in summer and 

overturn or upwelling in the cold months of December to February. 

Floating cage for tilapia culture (10 m x 10 m or 20 m x 5 m) was introduced in 1976. 

It expanded to 33 ha in 1991. The operators of the cages are small holders. The 

problem started when cage culture expanded to 6 ha (tilapia fingerlings raised to 

market size in about 13 months); in 1986, the fishfarmers started using commercial

feeds at a rate of 187 t/ha for three crops a year. For a collective area of 33 ha, 

about 6,000 t of feeds were dumped into the lake annually. 


1. Cage culture with intensive feeding is a potential polluter of aquatic 

ecosystems 

Feed losses, fish feces and other organic wastes generated by the cage culture 

resulted in the progressive disappearance of dissolved oxygen, a high BOD5 load 

and almost lethal concentrations of ammonia and total sulphides. In 1990, unaware 

of what was happening in the bottom layers, the cage operators sustained their 

feeding by negotiating for a few million peso-loan from a bank. SEAFDEC 

researchers working on the lake warned the operators about the possibility of a 

fishkill due to a large volume of anoxic and toxic waters that had developed 

underneath the cages and advised them to harvest the stocks. The warning was 

ignored and a massive fishkill of market size tilapia occurred. Cage operators lost 

their investment and had to shoulder the payment of the loan. 

2. Regulate fish cage area within 10-12 ha. of the lake surface area 

A team composed of SEAFDEC researchers, the Seven Lakes Fisherfolk Federation, 

the Foundation for the Philippine Environment and the Nationwide Coalition of 

Fisherfolk for Aquatic Reform recommended to LLDA the implementation of a zoning 

map that will reduce cage area to only 10-12 ha. (The scientific basis for the 

allocated area is not clear – just a rule of thumb.) 

Taal Lake 

Taal Lake is the third largest lake in the Philippines with a total area of 24,356 ha. It is 

one of the cleanest lakes with dissolved oxygen still high in deep layers. The lake has 

an endemic species, the freshwater sardine (tawilis). To date, tilapia cage culture 

occupies only 0.19% of the surface area of the lake. Stocking density for a 10 m x 10 

m x 5 m cage is about 10,000 tilapia fingerlings. Since the lake is not eutrophic, 

natural food is low requiring feeding for the culture. The impact of cage culture with 

intensive feeding in a congested area is beginning to show through the slow 

disappearance of dissolved oxygen in the water column. It is hoped that we have 

learned from the two previously mentioned lakes. The other impact to be monitored 

is the effect of the escaped tilapia on the population of the endemic species. The 

once scenic lake viewed from Tagaytay City is affected by the increasing number of 

floating cages that are beginning to look like floating debris. 

Prepared by: 

Alejandro Santiago

Integrated Development of Floodplain Wetlands 

in India 

Floodplain wetlands constitute a group of lentic water bodies associated with the 

floodplains of Indian rivers, known by different local names such as beels, chaurs, 

mans, boars, hoars and pats. They are usually cut-off river meanders (oxbow lakes), 

tectonic depressions, back swamps or sloughs, covering a total surface area of 

more than 200,000 ha spread over the eastern and northeastern regions of the 

country. Floodplain wetlands in India support subsistence and commercial capture 

fisheries, practiced by the local fisher communities. 

Multiple uses of wetlands and resulting conflicts 

Although fishing is the main economic activity in the floodplain 

wetlands, a wide range of other activities like irrigation, 

agriculture, duck rearing, post harvest activities, navigation and 

washing, are closely linked to these water bodies, making them 

a lifeline of rural West Bengal and Assam. Traditionally, these 

different activities have been carried out in harmony but in 

recent times, conflicts between agriculture and fisheries have 

become evident. Agriculturists would like to reclaim and convert as much 

lake area as possible into agricultural fields. A similar, though smaller, conflict 

exists within the fisheries segment -- among the intensive aquaculture, 

capture and culture-based fisheries. Attempts were made by the Central 

Inland Capture Fisheries Research Institute (CIFRI) to harmonize the various 

developmental activities by advocating an integrated approach.

Importance of capture fisheries in floodplain wetlands 

Continuous water renewal from rivers helps maintain capture fisheries in the open 

lakes on a sustainable basis. Encouraging fishery based on the wild stock of fish is 

essential for two main reasons: 

1. Maintaining the supply line of different species 

In India, there is growing discontent among the fish consumers over the dominance 

of major carps in the fish market. With the steady flow of catla and rohu from largescale 

aquaculture farms in the State of Andhra Pradesh, consumers have become 

species conscious. 

Consumers seem to be bored with 

the once coveted Indian major 

carps. Today, in all the major inland 

fish consuming states like West 

Bengal and Assam, local fish 

species (Anabas testudineus, 

Clarias batrachus, Heteropneustes 

fossilis, Gudusia chapra, 

Aspidoparia morar, 

Amblypharyngodon mola, Ompok 

pabo, Labeo bata, Puntius spp. 

and Channa spp., to name a few) 

have become more expensive. It is 

a common complaint in these 

states that the local species of fish 

are too expensive, so it is essential 

to keep the supply line of these 

species intact by retaining the 

capture fishery. In this context and 

considering the need to address 

the loss of biodiversity, capture fishery of the open floodplain wetlands assumes 

importance. 

2. Protecting the interests of traditional fishers 

Capture fishery is equally important in protecting the interests of traditional fishers 

who depend on fishing for livelihood. There is a growing tendency to convert the 

open waters into intensive aquaculture systems in coastal, mangrove and other 

wetland ecosystems. This is leading to many social conflicts. The traditional local 

fishers (often landless) are generally deprived of their right of access to common 

property resources. If alternative employment is not provided, their livelihood will be 

adversely affected and an already impoverished section will become poorer.

Augmenting the capture fisheries 

In order to increase production from the lakes, some culture practices can be easily 

incorporated without disturbing the existing practice of capture fisheries. A system of 

combining capture fishery and aquaculture has been developed by the CIFRI, 

which is practiced widely in the eastern and northeastern states of India. 

Under this system, a series of small enclosures are created along the periphery of the 

lake to be leased out to entrepreneurs for aquaculture. These enclosures can be 

made of earthen dikes (sometimes strengthened with water hyacinth removed from 

the lake) or bamboo mat barricades. Some of the enclosures can act as nurseries to 

rear fish seed both for aquaculture and stocking. When culture-based fishery is 

practiced, the connecting channel should be protected with wire mesh to prevent 

the stocked fish from escaping. 

Integrated systems 

Floodplain wetlands and areas along their margins already tend to become 

swamps: converting these marginal areas into paddy fields is a common practice 

among relatively resource-rich farmers. The lake area consequently shrinks. Fishers 

get marginalized in the process. This is a very common cause of conflict among the 

various water users. As some of the lakes serve as bird sanctuaries, environmentalists 

are often cautious about competing uses. The floodplain wetlands are used for a 

variety of other purposes such as navigation, jute retting, collection of edible 

aquatic mollusks and plants. Each activity affects other water users.

A plan has been developed to 

integrate the many uses of 

floodplain wetlands and minimize 

conflicts. The current example 

refers to a plan drawn for a 

floodplain wetland in West 

Bengal, India, which has a 

swampy southern portion and a 

relatively deep northern portion, 

where the river connection exists. 

The integration plan envisages 

developing agriculture and 

aquaculture in the southern 

portion, while leaving the 

northern part for capture and 

culture-based fisheries. There will 

be a dike separating the two 

segments of the lake and water 

flow to the agriculture and 

aquaculture activities in the 

southern segment will be 

regulated through small canals. A 

central marshy portion of the 

southern segment will be left to 

attract the migratory and local 

birds, which frequent the place. 

However, the long-term effects of 

this type of development on the hydrodynamics and natural biological productivity 

of the lake are not adequately assessed. 

Conclusion 

● Capture fishery should be maintained in as many open lakes as possible to 

keep up the supply line of different fish species into the market, conserve fish 

biodiversity and ensure the security of livelihood of traditional fishers. 

● Fish production in the beels can be increased to meet growing demands by 

carefully incorporating some culture methods. 

● Conflicts that arise among various water users in the floodplain wetlands can 

be resolved to some extent by planning various activities through an 

integrated approach. 

Prepared by: 

V. V. Sugunan

Freshwater Cage Culture of Chinese Carps 

Modern cage culture was introduced in China 

more than two decades ago. The techniques 

have spread widely across the country with 

varying degrees of adaptation to local 

conditions. Gradually, cage culture became 

one of the major aquaculture systems in the 

country. It has contributed remarkably to the 

improvement of living standards, ensuring food 

security, generating higher income and 

creating additional jobs. Cage culture of carps 

retains its importance in socio-economically 

disadvantaged areas in particular. 

Cage culture is very suitable to a wide range of 

open freshwater bodies, especially reservoirs. It 

may involve some risks of loss (fish escape, 

typhoon and flood, etc.) and require 

moderately high quality of artificial feeds in intensive culture.

Advantages of carps for cage culture 

Carps are native to the country. 

Local market demand is high due to a tradition of carp 

consumption, despite its relatively low price. 

Mature hatchery technology ensures the supply of 

quality seeds that are widely available at large quantities 

and low prices. 

Carps are low in the food chain or trophic level, thus, carp culture has 

less impact on the environment. 

Variations in the feeding habits of carps allow polyculture in cages 

with little or no competition for food between species. It gives farmers a 

wide range of choices regarding the level of intensity of culture. Carps 

accept many types of artificial or supplementary feeds. 

Some non-technical aspects have to be considered in developing cage culture. Fish 

culture is usually not the primary or high-priority user of a water body such as a 

reservoir. Development of cage culture is often influenced by the primary use or 

purpose of the water body, such as irrigation, navigation, water passage for flood 

control, etc. Some open waters of sightseeing or recreational value allow the release 

of fingerlings only and no other aquaculture activities or inputs. Cage culture with 

artificial feeding is discouraged or totally prohibited in reservoirs or lakes that are 

primarily sources of drinking water. On the other hand, growing filter feeders like silver 

carp and bighead are encouraged. These could help in harvesting nutrients by 

feeding on the plankton. 

Water bodies suitable for cage culture 

Generally, water bodies for carp culture should be suitable for cage installation: 

water quality should meet the general requirements set by the National Standard of 

Water Quality for Fisheries. For example, the pH value should be 7.0 – 8.5 and the 

dissolved oxygen should be above 5 mg/l for at least 16 consecutive hours in 24 

hours of monitoring and not less than 3 mg/l for the rest of the time. Other 

considerations include the flow/movement of water, site accessibility, etc. Inland 

waters used for cage culture include reservoirs, lakes, rivers, streams and canals, etc. 

Produce from cages 

Culture of large size carp fingerlings (also called yearling) in cages 

● From small fingerlings (about 3 cm) to large size fingerlings (50-100 g) 

● Usually in reservoirs and lakes. Large size fingerlings are produced for stocking 

in cages for the following year or for release into the lake or reservoirs, 

depending on the nature of the operation.

Culture of food fish in cages 

● From large size fingerlings to marketable size. 

Culture of food fish and fingerlings in same cage 

● Fingerlings and yearlings are stocked in cages at the same time. Marketablesized 

fish are harvested for selling at the end of culture cycle. The yearling 

grown from fingerlings continue to be cultured the next year but with a new 

batch of fingerlings. 

Major carp species for cage culture in China 

Filter feeders 

Silver carp (Hypophthalmichthys molitrix) and 

bighead carp (Aristichthys nobilis) are typical filter 

feeders. These two species feed mainly on 

phytoplankton and zooplankton, respectively. They 

are suitable for culture in relatively fertile water rich 

in plankton. They occupy different feeding niches 

and therefore, could be stocked in the same cage. 

Feeding is not applied in cage. Polyculture of silver 

carp and bighead in cages could yield up to 8 

kg/sq m if the water is abundant in plankton. 

However, the market value is relatively low. 

Herbivorous carps 

Grass carp (Ctenopharyngodon idella) and blunt 

snout bream (Megalobrama amblyocephala) are 

foraging species. Their natural food is aquatic plants 

but they will also eat terrestrial grasses, vegetables 

and pellet feeds. Grass carp is famous for being 

voracious and is a fast grower. Blunt snout bream 

grows moderately fast but its marketable size (300- 

500 g) is much smaller than grass carp (1.5 kg 

above). The market prices of these two species are 

higher than those for silver carp and bighead. 

Omnivorous carps 

Omnivore carps include common carp (Cyprinus 

carpio) and crucian carp (Carassius auratus). They

also feed on pellet feeds. Common carp can fetch 

a moderately high price, especially in northern 

China. Crucian carp is a bony fish favored by 

consumers in some provinces. 

Other indigenous carps 

Mud carp (Cirrhina molitrorella) from southern China 

and small scale fish (Plagiognathops micrrolepis) 

found in central and eastern China are cultured in 

cages as minor species. Their feeding habits are 

similar: feeding on leaves of plants, filamentous algae, 

detritus, epiphytic diatoms and some aquatic insects, 

etc. 

Types of cages used for carp culture 

For freshwater fish culture, cages are 

designed and constructed according 

to the conditions of the locality and 

locally available materials. There is no 

strict standard for the type of cage to 

be used. The size of the cage ranges 

from 1 - 200 sq m, although the 

majority are between 1 - 30 sq m. The 

general trend is to use smaller cages 

for easy management and 

maintenance and better exchange 

of water. Individual cages are 

arranged in such a way that 

maximum water exchange is 

achieved. It is generally 

recommended that water exchange 

be completed in each cage within 

0.5 - 1 minute. 

In shallow waters, stationary cages 

are constructed for fish culture. On 

the other hand, floating cages are installed in deep lakes and reservoirs. The bottom 

of stationary cages should be 0.5 – 1.0 m above the bottom of the water. Depth of 

the cage is usually 1.5 – 2.5 m for lakes and 2 – 4 m for reservoirs. 

Among locally available materials for cage construction, bamboo and ready-made 

polyethylene nets are commonly used. Such cages could last for three years.

Mesh size differs according to the purpose of culture. The mesh size for large carp 

fingerling culture is 1.0 - 1.5 cm. For grow-out culture, the mesh size depends on the 

size of seed to stock. An empirical equation for determining the net mesh size for 

cage culture of carps is widely accepted: 

Stocking 

Stocking for growing yearlings 

Monoculture is recommend for yearling culture. 

Seed fish from nursery pond for culture in cages 

should not be less than 3 cm in length. Very fine 

mesh size is needed for constructing the cage if the 

fingerlings are too small. The stocking density (150- 

600 fish/sq m) depends on food availability (in the 

water) and targeted size of yearlings at harvest. 

Stocking for grow-out 

Both monoculture and polyculture are employed for carp grow-out culture in cages 

in China. The smaller the cage, the higher the stocking density. With sufficient feeds 

available, the main factor limiting fish growth is oxygen and not fish density. Some, 

however, also suggest that high density of fish in the cage reduces fish movement, 

saving energy for growth. 

Filter feeders (silver carp and bighead) of 100 g sizes are stocked at 1-3 kg/sq m. 

Ratio between bighead and silver carp largely depends on the composition of 

planktons in the water. There should be 50-60% of big head for stocking if the ratio of 

zooplankton to phytoplankton in the water is 1:1000. Bighead could be increased to 

80% if the ratio is 2:1000. 

For other carps, the culture is usually semi-intensive or intensive (in terms of feed 

input). A generally recommended stocking density is 5-10 kg/sq m for a cage of 20- 

40 sq m in size and 10-20 kg/sq m for a cage of less than 10 sq m. The uniformity of 

yearlings of the same species is important to achieve good results at harvest. 

Routine management

● Feeding (non-filter 

feeders) Constant 

supply of feed of good 

quality at reasonable 

cost is important to 

ensure technical and 

economic viability of 

carp culture in cages. 

● Removal of leftover feed 

● Regular inspection of 

cage 

● Cleaning of net and 

removal of foul materials and organisms 

● Avoiding cage damage during typhoons or floods by taking precautions 

● Monitoring fish health and disease occurrence, apply medicines for disease 

prevention. 

Harvest and marketing 

● Harvest in fish cages is 

relatively simple and 

easy. 

● Careful handling is 

important to avoid 

injury to fish at harvest 

and during transfer to 

market. 

● Fish wounds result in 

lower market prices. 

Dead fish fetches a 

lower price than live 

fish. 

● Both partial harvest 

and total harvest can 

be applied to carp 

food fish culture in 

cages. 

● Farmers or farmer groups should learn to collect supply and demand 

information to develop market strategies. 

Reference 

Sifa, L. and J. Mathias (editor). 1994. Development of Aquaculture and Fisheries 

Sciences, 28. Freshwater Fish Culture in China: Principle and Practice. Elsevier

Science B.V. 

Prepared by: 

Zhou Xiaowei

Low-Cost Cage Culture in Upland Areas of 

Vietnam 

Cage culture is an intensive form of fish culture commonly practiced in rivers, lakes, 

streams, reservoirs and irrigation channels. 

Advantages 

● Allows for high stocking density because of free flowing water. 

● Locally available fish feed and material for making the cage. 

● All members of the family can participate, including women and elders. 

● Quick returns with high yields and profitability. 


● Away from the impact of industrial wastes and other polluting agents such as 

domestic waste from backyard pigs. 

● Away from river transportation routes. 

● Velocity of water flow of the river/stream should be about 0.2 to 0.3 meters per 

second (mps) for best results. 

● Area has clean, residual free unpolluted waste.

Cage design 

Two main types 

Placing cages 

1. Nylon net cage with bamboo or wooden skeleton 

size 4 m length x 3 m width x 2 m height. 

2. Bamboo or wooden cage size 5m length x 3m 

width x 1.6m height. The size of the cage depends on 

the water depth, velocity of water flow, materials 

used and capacity of the farmers. 

To avoid outbreaks of fish diseases, the distance between the cage bottom and 

sediment should be more than 0.5 m up to a distance determined by the depth of 

the water body. 

Recommended distances between one cage and the next should not be less than 

10-15 m. Distance between two groups of cages should be 150-200 m. 

These recommendations have become regulations that are now enforced by 

government fishery advisors from the Fisheries Management Department after they 

discovered a fish disease problem in 1994 (due to the close proximity of cages).

Cultivable 

species 

Chinese grass carp 

(Ctenopharyngodon 

idella), indigenous 

grass-eating carp 

(Spinibarbythis 

denticulatus), 

common carp and 

sometimes tilapia are 

the most popular 

species used for 

cage culture. 

Stocking density and size 

● Vigorous and healthy seed of 

uniform size (150-200 g/fish) 

are preferred for stocking the 

cages. 

● Stocking density is usually kept 

at 30-40 fish/m3 

Prophylactic treatment to prevent diseases 

Before stocking, give fingerlings a bath in a 2-3% salt solution for two to three 

minutes to prevent outbreak of common parasitic and microbial infections.

Care of cages 

Feeding 

Feed fish with locally available grasses, 

vegetation and other easily available 

items, like garlic which contains disease 

prevention/control properties. 

Most households produce feed as byproducts 

of their daily activities: leaves of 

maize, cassava, banana, rice bran, sweet 

potato, duckweed, etc. 

Initially, when the fish are small, chop grass 

and vegetation into small pieces for 

feeding. 

Nutrient rates: 

Green feed materials should be 20-25% (wet weight) and starch 1-2% of body 

weight per day. 

Cage cleaning 

This is carried out before 

stocking and after 

harvesting. 

Lift cages out of the water 

and brush them (in and out) 

using Ca(OH)2 (Calcium 

Hydroxide) solution and 

leave them to dry under the 

sun for one to two days. 

Clean the cages every week 

to remove all the dirt and 

waste stuck to the sides and 

bottom of the cage.

Harvesting 

After six to eight months, bigger-size 

fish are harvested first (3-4 kg) 

although depending on market 

price and demand, the rest can also 

be harvested. 

Yields can be 500-800 kg/cage. 

In Vietnam, during the "Tet" holidays, 

festivals, wedding season, 

consumption rises and prices 

increase, so it is a good practice to 

harvest fish then. 

Prepared by: 

Nguyen Huy Dien and Tran Van Quynh


Brackishwater and Marine 

Systems 

Community-Based 

Rehabilitation of Mangroves 

Mangrove-Based Small-Scale 

Shrimp Aquaculture 

Estuarine Aquaculture 

Systems 

Utilizing Coastal Wetlands for 

Small-Scale Aquaculture in 

Sri Lanka 

Successful Small-Scale 

Mudcrab Farming 

Development in the Thai Binh 

Province, Vietnam: A Case 

Study 

Management Practices to 

Improve Extensive Shrimp 

Aquaculture 

Farmers’ Methods of Oyster 

and Mussel Culture in the 

Philippines 

Mud Crab Systems for Small- 

Scale Aquaculture 

Small-Scale Seabass Culture 

in Thailand 

Coastal Aquaculture Options 

Brackishwater and Marine Systems

Community-Based Rehabilitation of Mangroves 

Mangroves are intertidal communities of tropical and subtropical trees and shrubs 

growing in salt to brackish water and in predominantly muddy or sandy substrates, 

and protected coastlines. To cope with extreme conditions (of salinity, water 

saturation and dessication and anoxia), mangroves have evolved a variety of 

coping mechanisms including prop roots, cable roots and salt glands. 

Facts 

Mangrove-associated fish contribute around 30% (1.09 million tons) 

of annual finfish resources (excluding fish bycatch) in the ASEAN region. 

Mangrove-dependent prawns provide almost 100% (0.4 million tons 

valued at US$1.4 billion) of total prawn resources in the ASEAN region. 

A review of mangrove fisheries gives estimates of production and 

value (on a per ha per yr basis) respectively, of 257-900 kg and US$475- 

5,330 for fish, 13-756 kg and $91-5,292 for penaeid shrimp, 13-64 kg and 

$39-352 for mud crab, and 500-979 kg and $140-274 for mollusks. 

Conversion to shrimp/fish ponds, in addition to settlements, 

agriculture, salt beds, overexploitation and other factors, have led to 

high rates of mangrove loss ranging from 25% in Malaysia to 50% in 

Thailand over the last three decades. 

Shrimp pond construction in mangroves totaled 102,000 ha in 

Vietnam in 1983-1987 and 65,200 ha in Thailand 1961-1993; many of 

these farms have collapsed due to diseases. The ponds were

subsequently abandoned. 

Mangroves produce both forest and fisheries resources and goods. Fisheries 

products include fish, shrimp, crabs, bivalve and gastropod mollusks, other 

invertebrates and seaweeds. 

A positive correlation between nearshore 

fish and shrimp catches and mangrove 

area has been documented in many 

countries. Declining municipal fisheries yields 

parallel the reduction of Philippine 

mangrove areas, while brackish water pond 

hectarage and aquaculture production are 

increasing. Although total fisheries 

production may remain the same, 

municipal fisheries provides equity by 

supporting many more people than pond 

culture. 

Several other products can be 

obtained from mangroves 

Aside from the products it provides, the 

regulatory function of the mangroves or 

the provision of amenities or services are 

equally important. These services 

include coastal protection, erosion 

control, sediment stabilization and 

trapping of terrestrial run-off, flood 

regulation, nutrient supply and 

regeneration, treatment of dissolved 

and particulate wastes, and habitat for 

wildlife. Total values as high as 

US$10,000/ha/yr have been estimated 

for all these mangrove goods and 

services.

Mangrove rehabilitation 

Rehabilitation is the restoration of a degraded system to a more stable ecological 

status, which may or may not be its previous condition (Lewis, 1999). 

The guiding principle in mangrove 

rehabilitation is the restoration of normal 

hydrological patterns. The community can 

draw on local knowledge of past 

hydrodynamics. Once the correct tidal 

elevation is restored, colonization by 

waterborne seedlings from adjacent stands 

can proceed. Planting should be undertaken 

only if natural mangrove recruitment does not 

occur, or if there is an overriding need by the 

local community for specific products, e.g., fishing poles from Rhizophora. Degraded 

areas with sparse mangrove cover can also benefit from enrichment planting of 

suitable species. 

Mangrove plantations 

At the outset, the stakeholders or local villagers should have a consensus on their 

goal in rehabilitating a given area. 

● Shoreline protection (pioneers Avicennia marina and Sonneratia 

alba/Sonneratia caseolaris) 

● Forestry products: Rhizophora for firewood, posts and piles; Ceriops tagal for 

tanbark; Xylocarpus granatum and Heritiera littoralis for furniture; and, Nypa 

fruticans for thatch (housing material) 

● Improvement of fisheries catches (by restoring habitat) 

Active mangrove planting of small areas – by villagers, local officials and 

schoolchildren as well – for educational purposes has greater importance than the 

total number of hectares planted. Nevertheless, tenure over the planted area will 

motivate planters to regularly monitor and protect the young seedlings. 

Seedlings should not be planted near strong water currents, on tidal flats that serve 

as feeding grounds of migratory birds and seagrass beds. Planting should coincide 

with the availability of propagules (in case of direct planting) and the season of least 

wave action and typhoons. Mangrove species to be planted will depend on 

biophysical conditions of substrate (A. marina, S. caseolaris in sand, Rhizophora in 

mud), wave action (A. marina in seaward locations, R. mucronata/R. stylosa/R. 

apiculata along rivers), salinity and tidal elevation. Species of Rhizophora have been 

favored by past and ongoing mangrove planting programs throughout Asia

ecause of their large propagules that are available year-round. Such monocultures 

have often failed. 

Planting density or spacing will also depend on the objective - closely spaced 

clumps of three seedlings for coastal protection, higher densities of Rhizophora for 

firewood and charcoal, and lower densities for timber. Maintenance and monitoring 

by the community in the first months require daily check-up for barnacles, 

filamentous algae as well as the replacement of dead plants. As the plants become 

established, visits can be less frequent . 

Mangrove seeds can be planted directly (e.g., the viviparous or germinated 

propagules of Rhizophora) or sowed (Sonneratia). Nursery-grown potted plants and 

hardened wildlings can also be outplanted in the field. 

Mangrove nurseries 

● Factors to consider in selecting a mangrove nursery site: 

– brackishwater (inundated by spring tides) and freshwater supply; 

– location close to mangrove seed sources, area for planting and 

village; and 

– accessibility preferably by land. 

● The nursery should be built on a cleared and level area that drains well. 

● Components include: 

– seed boxes (for small seeds like Sonneratia); 

– elevated germination beds; 

– beds for hardening of seedlings; 

– potting shed; 

– bagging shed; and

– storage shed. 

● Shading by means of coconut leaves or netting material is advisable to 

reduce sunlight. 

● The size of the nursery will depend on the number of seedlings required. 

Peak fruiting seasons 

● Undamaged mature seeds may be collected from the tree or on the ground 

when they have just fallen. 

● The growing tips of propagules should be protect during transport. 

● Mature seeds of each species have their own characteristics. 

● Propagules must be planted within a week after collection. 

● If seeds and propagules are not sufficient, wildlings or young saplings less than 

30 cm tall from mature stands may be used. Plants in newly-colonized 

mangroves should not be used. 

Community participation and ICZM 

Since the local residents are the users, the management of coastal resources 

(including mangroves, sea grasses and coral reefs) should be community-based. 

Community involvement in the planning and implementation of coastal resource 

management (CRM) projects and sharing in the benefits of the interventions will 

contribute to the success of CRM. This may require organizing community 

organizations in coastal villages and leadership training under the initiative of local 

government bodies or non-government organizations (NGOs). Rehabilitation and

other mangrove management projects shall be in the context of a wider integrated 

coastal zone/area management (ICZM or ICAM) that coordinates the needs of 

various sectors: fisheries, aquaculture, forestry, industry, among others. 

Socio-economic considerations in mangrove rehabilitation 

programs 

● Local knowledge and skills 

● Social organization and institutions 

● Land use and tenure 

Tenure over mangrove areas 

In many countries, mangrove areas are open access public lands owned 

by the government. It is important that mangrove planters (individual 

families or groups) obtain tenure over their respective areas whether in the 

form of management/stewardship contract or lease from the government. 

Such mechanism ensures that they will reap the benefits of what they sow. 

The successful conservation of the 300-ha Talabong Mangrove Reserve 

and decrease in illegal pond expansion and illegal fishing in Bais Bay, 

Negros, Philippines were due to the personal commitment of the mayor 

and local officials, community empowerment and provision of tenurial 

instruments. In turn, populations of various whales and dolphins that have 

subsequently returned to Tanon Strait outside the Bay provide opportunities 

for ecotourism along with mangroves, seagrasses and coral reefs in the 

Bay. 

The successful mangrove replanting projects of Yad Fon, a local NGO, in 

Trang Province, southern Thailand emphasize education and community 

involvement in the protection, monitoring and evaluation of rehabilitated 

sites. 

Co-management of CRM with local government units is essential because local 

officials are responsible for the enactment of ordinances pertaining to marine 

conservation and rehabilitation and their implementation. Effective enforcement of 

such regulations is hampered by lack of manpower and facilities, and corruption at 

various national and local government levels. However, the successful comanagement 

of Bais Bay, central Philippines illustrates political will at work. Local 

governments also have a role to play in conflict resolution - within the community 

and between neighboring communities. 

Aside from local government support, property rights and community involvement, 

other factors important in mangrove rehabilitation and CRM initiatives are effective

information dissemination/educational programs, and external technical expertise 

and funding, and alternative livelihood options. 

Alternative short-term sources of income may be: 

● cottage industries such as weaving and basket making; and 

● sale of nipa thatch, seaweeds, mollusks, crabs and fish from mangrove 

fisheries/small-scale aquaculture. 

Mangrove-friendly aquaculture includes the growing of seaweeds (Gracilaria), 

bivalve molluscs (oyster, mussel and cockle) and fish in cages/pens in mangrove 

waterways and tidal flats. Mudcrabs, fish and shrimp can also be cultured in pens 

and ponds integrated with mangrove trees inside the forest itself (called 

aquasilviculture or silvofisheries). 

It is particularly important that the planters, i.e., the villagers (or even landless poor 

from neighboring areas) are allowed to harvest fish, invertebrates and other 

products from rehabilitated sites. Gleaning of molluscs and other invertebrates for 

domestic consumption in tidal flats adjoining mangroves is often done by women 

and children. Moreover, such small-scale fishing and gleaning in inshore areas are 

more species-selective, less fuel- and time-consuming, and safer than deep-water 

fishing. 

Successful mangrove rehabilitation depends on both sound ecological principles 

and participation of local communities and government officials. 

References 

Hachinohe, H., O. Suko and A. Ida. 1997. Nursery Manual for Mangrove Species at 

Benda Port in Bali. Ministry of Forestry and Estate Crops, Indonesia and Japan 

International Cooperation Agency. 

Lewis, R.R. III. 1999. Key Concepts in Successful Ecological Restoration of 

Mangrove Forests, pp. 19-32. In: Proceedings of the TCE-Workshop No. II, Coastal 

Environmental Improvement in Mangrove/Wetland Ecosystems, 18-23 Aug. 1998, 

Danish-SE Asian Collaboration in Tropical Coastal Ecosystems (TCE) Research and 

Training. NACA, Bangkok, Thailand. 

Melana, D.M., J. Atchue III, C.E. Yao, R. Edwards, E.E. Melana and H.I. Gonzales. 

2000. Mangrove Management Handbook. Department of Environment and 

Natural Resources, Manila, Philippines. 

Primavera, J.H. 2000. Development and Conservation of Philippine Mangroves: 

Institutional issues. Ecol. Econ. In press.

Primavera, J.H. and R.F. Agbayani. 1997. Comparative Strategies in Communitybased 

Mangrove Rehabilitation Programmes in the Philippines, pp. 229-243. In: 

P.N. Hong, N. Ishwaran, H.T. San, N.H. Tri and M.S. Tuan (eds.) Proceedings of 

Ecotone V, Community Participation in Conservation, Sustainable Use and 

Rehabilitation of Mangroves in Southeast Asia. UNESCO, Japanese Man and the 

Biosphere National Committee and Mangrove Ecosystem Research Centre, 

Vietnam. 

Ronnback, P. 2000. The Ecological Basis for Economic Value of Seafood 

Production Supported by Mangrove Ecosystems. Ecological economics 29: 235- 

252. 

Sinohin, V.O., D.C. Garcia and S.R. Baconguis. 1996. Manual on Mangrove Nursery 

Establishment and Development. Ecosystems Research and Development 

Bureau, Department of Environment and Natural Resources, College, Laguna, 

Philippines. 18 p. 

Prepared by: 

Jurgenne Primavera

Mangrove-Based Small-Scale Shrimp 

Aquaculture 

Mangrove-based small scale aquaculture can take many forms. Some examples 

are: 

● culture of blood cockles and other shellfish on mudflats to the seaward of 

mangroves; 

● cage or rack culture of oysters, other shellfish and fish in mangrove estuaries; 

● culture of mud crabs within mangrove areas; and 

● pond culture of shrimp and fish within or adjacent to mangroves. 

Mangroves are not the best site for aquaculture ponds, especially for shrimp culture, 

as they have potentially acidic soil. Shrimp ponds may have problems with low pH, 

which is bad for the health and survival of shrimp. Also, when mangroves are 

converted into aquaculture ponds, valuable environmental benefits are lost. In 

general, it is better to set up aquaculture ponds on higher land behind mangroves.

The putting up of new aquaculture ponds within mangrove areas should be 

discouraged. However, brackishwater shrimp ponds have already been built in many 

areas. 

Some environmental and economic benefits of mangroves 

Help protect coasts and river banks from erosion 

Help protect coastal dwellers from storms and storm surges 

Help reduce peaks of nutrient and sediment discharges from coastal 

rivers 

Help trap sediment and build new land 

Help reduce atmospheric CO2 levels by fixing and storing carbon 

Produce leaf litter and other detritus that support coastal food chains 

Provide nursery and feeding ground for fauna, including 

commercially valuable fish, shrimp, crab, gastropods and bivalve 

species 

Provide timber and fuelwood for coastal dwellers 

Provide other products like honey and medicinal drugs 

Enhance biodiversity 

Provide aesthetic and recreational values 

Provide scientific, educational and cultural values 

In 1986, the Provincial Government of Ca Mau, the southernmost province of 

Vietnam, established 22 mixed shrimp farming-mangrove forestry enterprises (SFFEs) in 

the brackish water, coastal lowlands of Ngoc Hien and Dam Doi districts where 

Vietnam’s largest remaining mangroves are found. It aims to provide income for 

small-scale landholders while managing the remaining mangrove resources for 

timber/fuelwood production and for environmental reasons. 

Under the SFFEs, farming households are allocated 6-10 ha of land on a 20-year 

lease. At least 70% of the land is for mangrove forestry and the rest for aquaculture 

and domestic use. Shrimp culture is the primary livelihood for most households, 

although income from extensive wild shrimp culture remains low. This is partly due to 

unreliable wild seed stocks, particularly of species with high commercial value like P. 

merguiensis and P. indicus (low value Metapenaeids now represent about 80% of the 

harvest). Extensive culture of hatchery-reared seed of black tiger prawn (P. 

monodon) is also practiced widely, but yields and economic benefits have been 

highly variable because of low survival (commonly less than 1%) due to poor pond 

design and water and seed quality; bad farm management practices, farmer 

inexperience and disease outbreaks.

Some general characteristics of shrimp farming forestry enterprises (SFFEs) 

Flat with an elevation of less than 1 m above highest tide. 

Much of the area is tidally flooded from 150 to 365 days per year. 

Pronounced wet (May to November) and dry (December to April) 

monsoonal climate. 

Small-scale improved extensive and semi-intensive shrimp culture 

Increasing the stocking density (up to, but not more than, 10 per meter) and the 

survival rate of P. monodon in the pond can improve the contribution of shrimp 

farming to the livelihood of small-scale farmers in coastal areas. This can be 

achieved through modest intensification, together with better pond design, good 

quality seed and improved farm management practices. A range of options for 

improvement require different levels of investment. It is necessary to show farmers a 

sequence of steps they could take to increase their income. These steps depend on 

the condition of the farm, individual financial circumstances and experience. 

The three main requirements 

1. A good pond 

2. Strong, high quality and disease-free seed 

3. Good nursery care during the first 20-25 days of stocking 

Two types of farming systems commonly used in Ca Mau Province 

1. Separate farms where shrimps are cultured in ponds without mangroves. 

Mangroves are grown in a separate area of the farm, sometimes in combination 

with shrimp culture, like mixed farms. 

2. Mixed farms where mangroves are grown entirely within the pond, much like 

the tambac aquaculture system used in Indonesia for centuries.

Some general suggestions 

on farm layout 

● Remember that coastal 

mangrove systems are highly 

dynamic and their 

characteristics often change. 

What is seen now may not be 

the same in 10-20 years time. 

Try to anticipate future 

changes and make plans with 

these in mind. This will help 

avoid future problems that 

might be costly to fix. 

● Try to keep a 20-30 m wide belt 

of mangroves along the 

waterfront to reduce erosion 

and provide a nursery for wild 

aquatic species. 

● Try to maximize the benefit of 

mangroves by arranging the 

location to allow incoming or 

outgoing water to pass through the trees. 

Pond design 

A small pond with a water area 

of about 2000 or 2500 sq m is 

better than a much larger pond. 

Big ponds are more difficult to 

manage. Start with one pond, 

then add another as capital 

becomes available. This will help 

reduce the risk of losing shrimp 

through disease. No more than 

three ponds of this design should 

be built. See suggested 

sequence for the two main farming systems in the illustrations.

Suggested sequence for improving mixed farming system 

Suggested sequence for improving the separate farming system

Some useful tips on pond preparation 

● Use a sedimentation pond to improve water quality if the intake water has low 

transparency, is polluted or otherwise of low quality. Generally the water 

surface area of the sedimentation pond should be at least equal to the water 

surface area of the growout ponds. The sedimentation pond can be stocked 

with P. monodon at a density of 1-3 per sq m or it can be used for wild shrimp 

culture. 

● Do not dump the excavated material into the river or in mangrove areas. Use it 

to build an area above the tidal limit, which can be used for terrestrial crops or 

livestock production. Diversification can help reduce the risk to the household 

and provide a more stable income. 

● Make sure the average pond water depth is 1 m. 

● Use a cement water gate that is at 

least 1 m wide. If necessary, use 

plastic sheets or fibro-cement 

roofing material to prevent water 

leakage through crab burrows 

along the sides of the water gate 

(refer to the diagram on the right). 

● Outer levees (or dikes) should be at 

least 4-6 m wide to reduce leakage 

(10 m is preferable). The levee 

(dike) around the pond should be 

at least 0.5 m higher than the 

highest tide to reduce the risk of 

shrimp being washed out of the 

pond by unusually high tides or 

storm surges. 

● After constructing or after cleaning 

the pond, open the watergate and 

allow the tide to free flush the pond for at least a week. Put a net at the water 

gate to prevent entry of predators (e.g., fish). Avoid using chemicals to kill 

predators. If absolutely necessary, use only sparingly. Use Derris root or teaseed 

powder, both natural products, if piscicides are needed. In some areas with 

acidic soils, it may be necessary to apply lime (for recommendations, see 

paper on Management Practices to Improve Extensive Shrimp Aquaculture). 

● Prepare a nursery area at least 1 week prior to stocking, using fine net (=< 1 

mm mesh size) to cordon off the nursery from the rest of the pond. The size of 

the nursery area should be calculated for a stocking density of about 35-50 per 

sq m.

● Construct a survival net (mesh size =

Nursery care tips 

Feed daily, preferably with finely powdered commercially 

manufactured feed. Do not use crustaceans or crabs as feed. 

Feed in the nursery at the rate of 0.2 kg feed/ day/ 10,000 PL for the 

first 5 days, then increase to 0.5 kg feed/day/10,000 PL for the rest of the 

nursery phase. 

Spread the feed as evenly as possible across the whole nursery area, 

including survival nets. 

When buying PL, allow for a 30% loss during the nursery phase. Buy extra PL to give 

the desired final stocking density. 

Do not put more than 2,000 PL in a single bag. Transport PL from the hatchery to the 

farm as quickly as possible in late afternoon to avoid temperature stress. Give the PL 

a chance to adjust to nursery water conditions overnight. Before stocking, acclimate 

the PL to nursery water in large tubs or bins for 30 minutes with aeration. Gently 

release PL into nursery area. Do not forget to stock the survival net with the required 

number of PL. 

At the end of the nursery phase, count the survivors in the survival net. Use this to 

estimate survival and the stocking density at the beginning of the grow-out phase. 

Grow-out 

Use feeding trays to monitor feed intake. Don’t overfeed as uneaten feed will only 

cause problems with water quality, particularly if the pond is not aerated with 

paddle wheels. 

Aeration with a paddle wheel(s) is optional, but it is likely to increase survival at 

stocking densities up to 5 per sq m without feeding. Aeration is recommended for 

stocking densities of 5-10 per sq m with supplementary feeding (this will depend on 

the financial capability of individual farmers). Aeration is essential for stocking 

densities above 10 per sq m, when supplementary feeding is also necessary. Harvest 

in 90-120 days. Clean the bottom of the pond after each crop.

Stocking cycles 

Management during growout 

Keep the water level in the pond topped up. For stocking densities 

up to 10 per sq m, it may not be helpful to change water too 

frequently, especially if the quality of intake water is worse than that in 

the pond. 

Drain the surface water during heavy rain to reduce rapid changes 

in salinity and pH. 

Check and record the size and number of shrimp in the grow-out 

pond at least every seven days using a feed tray, lift net or cast net. A 

sharp decline in the number of shrimps may indicate a problem. If 

shrimps are of marketable size, then harvesting could be considered 

rather than risk losing most of the crop. 

Avoid stocking P. monodon at times when water quality may change rapidly, for 

example at the beginning of the wet season. A wet season crop has a greater 

mortality risk due to rapid changes in salinity and pH. Try to stock a wet season crop 

as early as possible, before heavy rains start. Drain and clean the pond bottom 

between crops, then leave the pond dry for two to three weeks before refilling. 

Health management 

Shrimp health is affected by water quality, availability and quality of feeds, and viral 

and bacterial diseases. For brackishwater mangrove-based shrimp culture, especially 

in Ca Mau, Vietnam, low oxygen levels and pH are likely to be the main water quality 

parameters influencing shrimp health. Low oxygen can be a more serious threat 

when the ponds are overstocked or if shrimps are overfed. In the wet season, rapid 

changes in salinity may also affect shrimp health adversely. These problems can be 

minimized by careful water quality management.

Viral and bacterial diseases are more difficult to manage. Using disease-free seed is 

the first step that farmers can take to reduce the risk of diseases. However, viral and 

bacterial pathogens are probably present in most wild shrimp populations, so that 

there is always a risk that disease can be transferred from wild to cultured shrimps 

that were initially healthy. Crabs can also be vectors of some shrimp diseases. Hence, 

it would be best to exclude wild shrimp and crabs from the grow-out pond. Shrimps, 

like all animals including humans, are more likely to contract a disease if they are 

weak or stressed. Good pond and water quality management practices that keep 

shrimps strong and healthy will also help reduce the risk of death from viral and 

bacterial diseases. 

Mangrove silviculture 

The most common mangrove species used for silviculture (cultivation of timber trees) 

is Rhizophora apiculata, which is very suitable for poles, fuelwood and charcoal. For 

optimum growth, this species should be propagated in areas that are flooded for a 

period of 10 to 25 days per month. 

It is also best to plant this species with an inter-tree spacing of 1 to 1.25 m (8,000 to 

10,000 trees per ha) for silviculture. Specific thinning plans will depend on site 

conditions and the growth rate. For Ca Mau Province in Southern Vietnam, this 

species should be thinned to 5,000 trees per ha at eight years. If the trees are farmed 

on a 20-year rotation, a second thinning to 2,000 or 2,500 trees per ha should be 

carried out at 14 years. Rhizophora forests should not be thinned after 20 years of 

age. 

Benefits from integrating mangroves with aquaculture 

There are direct economic and environmental benefits from integrating mangroves 

with coastal aquaculture: 

● mangroves can be used to process and clean up intake and outflow water in 

aquaculture ponds. To do this efficiently, farm layouts should be designed with 

this in mind; 

● mangroves provide protection from storms and may prevent the loss of land 

from erosion, especially along the waterfront; 

● generate income from the sale of wood products; 

● provide fuel and materials for construction of houses, footbridges and other onfarm 

activities; and 

● honey raising can be integrated in areas where there are suitable species of 

mangrove. 

Prepared by:

Barry Clough

Estuarine Aquaculture Systems 

The estuary is the interface between the freshwater and marine ecosystems. As such 

it has the following characteristics: 

● Highly variable salinity with the range depending on the volume of freshwater 

inflow 

● Relatively more turbid than the open sea 

● Generally nutrient rich with high primary productivity 

● Generally high flushing rate 

● Often a rich fishing ground 

The estuary may be a whole bay or the immediate vicinity of the mouth of a river or 

a creek both upstream and downstream. Indeed there can never be a sharp 

delineation of the boundaries of an estuary. Its extent and the variability of its 

physical, chemical and biological characteristics depend on the tidal conditions and 

the weather. Thus the salinity of an estuary varies in time as well as with depth and 

distance. Salinity increases with depth and distance from the freshwater source. 

Selection of species suitable for culture in estuarine environments 

Even if purely marine or purely freshwater species are found within an estuarine area, 

not all species of fish and other aquatic organisms will be suitable for culture in an 

estuary due to its dynamic nature. Ordinarily, a swimming species will just move away 

from conditions not favorable to its survival. Since aquaculture entails confining the 

organism to a definite location, only species with the following characteristics can be 

considered for culture in an estuary: 

● tolerant of fluctuations in salinity; and 

● not sensitive to occasional high turbidity.

The continuous presence of a species in an estuary regardless of tidal conditions can 

be considered the best indicator of its suitability. 

In addition to the biological requirements of a species, there are logistical and 

economic factors that have to be considered as well. These are: 

● a good market and ready access to that market; 

● locally available feed at low or no cost; and 

● available seedstock (fry, fingerlings, spats, etc) 

Suggested species for culture 

The following species are either known to have been grown or, from their distribution 

and occurrence, should be suitable for culture in estuaries: 

Agarophyte seaweeds (Gracilaria spp.) 

● Viability depend on availability of market 

● May be grown by planting cuttings on shallow bottoms 

or tied to lines or nets attached to fixed posts or afloat 

● Sold fresh for direct human consumption and in dry 

form for processing into agar 

Oysters (Crassostrea spp., Saccostrea spp.) 

● Require plankton-rich water 

● Can tolerate lower ranges of salinity and higher 

turbidity 

● Maybe raised in shallow or even intertidal areas 

● Should ideally be raised in clean, uncontaminated 

waters 

Mussels (Perna viridis) 

● Require plankton rich water 

● Cannot tolerate prolonged exposure to low salinity 

ranges 

● Best grown in deeper waters 

● Best grown in clean, uncontaminated waters

Cockles (Anadara spp.) 

● Require plankton rich waters 

● Require wide expanse of flat, shallow and soft subtidal 

beds 

● Preferably grown in areas with low population density 

and far from industries 

Penaeid shrimps (Penaeus spp.) 

● Of many possible species, jumbo or black tiger shrimp, 

Penaeus monodon, grows fastest and attains largest 

size 

● Black tiger shrimp tolerant of wide ranges of salinity but 

grows best in brackishwater 

● Maybe grown in pens 

● Require fish or molluscan biomass or formulated feed. 

Mud crabs (Scylla spp.) 

● Tolerant of wide range of salinity 

● Can be raised in bamboo pens or cages 

● Use of cage usually for short-term fattening 

● Require animal protein diet (fish, mollusk, poultry 

waste) 

● Not yet bred in hatcheries so seedstock may be a 

problem. 

Milkfish (Chanos chanos) 

● Tolerant of wide salinity range from freshwater to 

above seawater salinity 

● Demand limited to few countries (Philippines, 

Indonesia) 

● May be grown in cages or in pens 

● May be fed rice bran but grows better with formulated 

feed 

● Fry available seasonally but may also be produced in 

hatcheries

Mullet (Mugil spp.) 

● Tolerant of wide salinity range 

● Demand maybe regional 

● May be grown in cages or in pens 

● May be fed rice bran but grows better with formulated 

feed 

● Fry available seasonally but may also be produced in 

hatcheries 

Tilapia (Oreochromis spp.) 

● Nile tilapia can tolerate salinities up to 15 ppt but 

higher salinity will require saline tolerant breeds such as 

O. niloticus + O. mossambicus hybrids 

● May be raised in pens or cages 

● May subsist on algae but high density in cage or pen 

requires feeding with formulated feed 

Seabass (Lates calcarifer) and Mangrove snapper (Lutjanus 

argentimaculatus) 

● Tolerant of wide range of salinity but grow better in 

lower salinity 

● Best raised in cages 

● Require fish biomass 

● Fry/fingerlings may be collected from natural waters, 

but may also be available from hatcheries. 

Groupers 

● Cannot tolerate low salinity levels, grow best in 25 ppt 

or higher 

● Command high price when sold live so accessibility to 

market very important 

● Best grown in cages 

● Require fish biomass as feed 

● Propagation in hatcheries not yet widespread and 

natural so fingerlings supply can be a problem.

Pen versus cage 

Rabbitfish 

● May not tolerate salinity below 15 ppt 

● May be grown in pens or cages 

● Can be fed vegetable wastes and/or seaweeds 

● Wild fingerlings occur in abundance seasonally but 

may also be produced in hatcheries 

The main difference between a pen and a cage are as follow: 

● Pen – a net and/or bamboo enclosure utilizing the natural seabed as the 

bottom barrier 

● Cage – an enclosure that may be installed off-bottom (either on fixed frame or 

afloat) that has net material as bottom barrier 

Generally, a pen would have a more adverse impact on the estuarine environment 

for the following reasons: 

● It tends to require larger areas. 

● It can only be installed in shallow areas making it more likely to obstruct access 

to the water body. 

● It cannot be moved. 

● It extends from the surface of the water all the way to the bottom impeding 

the flow of water more than cages, thus, has greater tendency to increase 

siltation rate. 

Considerations in estuarine aquaculture 

● Access by other users to common resources should not be limited. 

● Navigation and right of way of boats should not be blocked. 

● Flow of water should not be substantially affected so as not to increase siltation 

rate. 

● Feeding should not compete with local requirements for human nutrition. 

● Culture structure should not be crowded and the natural carrying capacity of 

the estuary should not be exceeded. 

● Installation should not result in the destruction of mangrove and wetland areas. 

● Materials for contruction should not be taken from endangered plant species 

nor treated with chemical preservatives. 

Minimizing adverse impacts

● Organize coastal communities so all stakeholders can participate in 

development planning and resource management. 

● Work for adequate legal framework and compliance with existing laws. 

● Give priority rights to local community over the use of estuary. 

● Zone the estuary to provide access to all users, setting aside open areas for 

fishing and areas for pens, cages and other culture systems. 

● Identify and use as feed species considered as pests or not usually used as 

human food such as golden apple snail and undersized tilapia from fishponds 

and shrimp ponds. 

Prospects for livelihood 

When a sound estuary development and management system is in place, the 

potential of estuaries in providing aquaculture-based livelihoods to the coastal poor 

is high. Aquaculture in an estuary has to be planned as an integral part of an estuarywide, 

community-based, coastal resource management program. 

Prepared by: 

Fred Yap

Utilizing Coastal Wetlands for Small-Scale 

Aquaculture in Sri Lanka 

Wetlands are defined as areas of marsh, fen, peat land or water whether natural or 

temporary, with water that is static, flowing, fresh, brackish or salt. These include 

areas of marine waters, not exceeding six meters indepth during low tides. 

According to the Ramsar convention, many parts of Sri 

Lanka qualify as wetland. More than 20 different types of 

wetland ecosystems can be identified in the country. 

Surface waters of Sri Lanka are divided into three main 

groups: freshwater, salt water and human-made. 

The three types of wetlands have been further subdivided 

into ten general wetland types: reservoir, streams and rivers, 

fresh water marshes, deltas and estuaries, lagoons, marine 

wetlands, tanks and reservoirs, agricultural wetlands, salt pans and aquaculture 

ponds. 

Freshwater 

Reservoir Streams/river F/W marshes

Saltwater 

Humanmade 

Deltas and 

estuaries 

Lagoon Marine marshes 

Lake Agricultural Saltpans Aquaculture ponds 

Small-scale coastal aquaculture development in wetlands 

Coastal aquaculture development has become an important 

activity in the country’s economy. In 1998, Sri Lanka earned 

6732 million Rupees (US$1=Rs 78) from exports of fish and fishery 

products. 

Sri Lanka has a coastline of 1585 km encompassing lagoons, 

estuaries, bays and fringing reefs. Lagoons and sheltered bays 

are common along the coast and are potential sites for 

aquaculture development of a variety of species. In addition, 

mangroves play an important role in coastal aquaculture by 

providing natural breeding grounds and shelter for aquatic 

organisms. 

Most of coastal habitats suitable for small-scale 

aquaculture lie on the eastern and northern coasts. 

The western and southern coasts have little potential 

for aquaculture. Shrimp farmers dominate the 

northwestern coast. At present, only shrimp culture 

has been commercialized in Sri Lanka. The variety of 

species, which at present have the potential to be 

cultured, is remarkably wide. Most of the species are 

suitable for small-scale farming. The potential for 

aquaculture depends on the choice of fish species 

and culture system. Various criteria are used to assess

if a species is suitable for culture. 

Matrix of species 

The species included in the matrix have been selected from a technical standpoint 

only. Although it may be technically possible to grow species in the coastal zone of 

Sri Lanka, the special conditions needed to develop commercial aquaculture may 

not be present. Following are species included in the matrix: 

Mud crab 

Two species of mud crab are found in Sri Lanka waters, Scylla 

serrata and S. oceanica. Mud crab fattening is increasingly 

popular among the resource poor coastal fisher folks. A recent 

practice is to hold molted water crabs for two to three weeks, 

feeding them with fish offal. Mud crab culture in ponds is 

likewise, done on a limited scale. The normal culture period is 

six to eight months. This is well suited for small-scale operations and can be done in a 

way that minimizes environmental impact. 

Oyster 

Field trials by National Aquatic Research Development Agency 

(NARA) demonstrated the feasibility of culturing systems. The 

most promising sites are to be found in the extensive lagoons 

and embayment of the east and northeast coast of the 

country. NARA scientists have developed appropriate methods 

for farming Crassostrea madrasensis in Sri Lanka. Weak local 

market demand is the major constraint in the development of 

oyster culture in Sri Lanka. Tourism offers opportunities provided the product could 

be certified as sanitary. 

Seaweed 

The genus Gracilaria is found in sea grass beds in the lagoons and 

bays around the coast of the country. The work carried out by NARA 

on Gracilaria culture indicated that there was a significant potential 

for its development in aquaculture. Seaweeds can be used in making 

jelly and to extract agar, which has both domestic and export markets 

depending on quality. 

Hybrid tilapia

Hybrids of Oreochromis spp exhibit rapid growth and have 

high feed conversion ratios. Brackish ground water is 

common along the coastline of Sri Lanka and could be 

used to culture hybrid tilapia in small ponds. While this fish 

can tolerate a wide range of salinity, there should be no 

abrupt changes. Tilapia is also cultured in abandoned 

shrimp farms. 

Sea cucumber 

Sea cucumber, also known as trepang or beche de mer, is 

highly priced in East Asian markets. Its habitat requirements 

under culture conditions are not well known. However, the 

species are found in muddy sand sea floors. The most 

valuable species are: Holothuria scabra, H. nobilis and H. 

fuscogilva. 

Brine shrimp 

Brine shrimp or Artemia is widely used in the 

ornamental fish industry. It is vital to the shrimp 

and prawn hatchery business. Field trials done by 

NARA demonstrated the feasibility of both 

biomass and cyst production in the south and 

northwest coasts of Sri Lanka. Some 

commercialization has developed to supply local 

markets in the ornamental fish and hatchery 

sectors. 

Freshwater prawn 

Freshwater prawn or Macrobrachium rosenbergii is used in 

mono and polyculture fishponds. Culture of freshwater 

prawn in small-scale is a profitable venture. 

Marine finfish 

At present, marine finfish culture is limited to seabass, 

groupers and milkfish. Seabass and grouper are reared in cage systems. Both milkfish 

and seabass cultures are done in abandoned shrimp farms using seed collected 

from the wild. A government supported hatchery and demonstration farm could 

provide the necessary inputs to start an industry. Due to declining coastal fisheries 

and overexploited lagoon resources, there is an increasing interest in fish culture to 

enhance fish production, combined with aquaculture technology and community 

management of local fishery resources.

Need for zoning coastal aquaculture 

Haphazard development of aquaculture inevitably leads to environmental overload 

and conflict among user groups and serious economic losses to the industry. The 

uncontrolled expansion of shrimp farming in Sri Lanka is just one of many examples of 

the consequences of inappropriate setting, overcrowding and destruction of 

mangroves. 

Geographical Information Systems (GIS) technology gives the planner and 

developer the capacity to evaluate the interaction of a wide range of 

environmental and social factors that affect the potential of a region for 

aquaculture development. The complexity of environmental and other influences is 

integrated through a ranking and scoring system using maps or ‘layers’. 

Based on the result of GIS-based zoning, aquaculture development can be targeted 

at suitable areas through a permit process effected by, among others, committees 

at the national and provincial levels. The developer and financial institution can 

evaluate the feasibility of projects more readily. 

The zoning matrix 

Shrimp culture alone has been developed as a commercially viable technology in 

Sri Lanka. However, a number of other species have shown promise. Some of these 

have been subject to experimental farming while others have been successfully 

farmed in various tropical countries. Many are well suited for small-scale production 

and could have a positive impact on the economics of small fisher folk communities. 

Various criteria have been identified according to their impact on the technical 

feasibility of culture of the species included in the zone-matrix. Criteria are ranked 

according to their relative importance for each species. They are further refined by 

parameters which indicate the range over which a particular criterion affects the 

culture system. 

Matrix criteria 

Certain criteria that affect or control aquaculture systems development were 

identified and ranked. Ranking was done on a 4-point scale, represented on layers 

by a monochrome shading scale. The ranking scale was set up as follows. 

Criteria Point 

Not suitable for development 0

Not optimal, affects the culture system negatively 1 

Neutral, or favors the development of the culture 

system 

Positive and successful development likely 3 

● Parameters are ranked using the same scale applied to criteria. 

● The rank score for a criterion is the product of the criterion rank by the 

parameter rank. 

● In situations where data are insufficient to rank parameters, an approximation 

of the score for a criterion may be used. In this case, the score is more intuitive 

than objective, as it would be based on general experience. 

● The score for a species within the area in question can be indicated by the 

sum of its criteria scores. Assigning a value of reallign to a parameter is 

intended to remove sensitive sites from consideration. 

● Subtracting their areas from the base map can do this. This will protect critical 

wetland habitats and direct development away from them and other 

unsuitable areas. 

Physical, chemical and social parameters affect aquaculture development, but 

obviously not all parameters are applicable to every system considered. If a criterion 

or parameter does not apply to the species in question, its cell is left blank in the 

matrix. 

Zoning for coastal 

Steps for zoning coastal aquaculture 

2

Preparation of base maps and layers 

● Find, collect and collate maps, reports, studies and surveys from published or 

unpublished literature. Digitized maps of the coastline including lagoons, bays 

and harbors serve as base map. Large areas of coastline fall within certain 

depths of some parameters like elevation. 

● Construct a series of digitized layer maps of criteria relevant to each species or 

species group. Plots are developed from data shown on a 1:50,000 scale maps 

or from specialized maps of soil. 

● After layers of criteria have been completed, the parameter can be ranked 

through the color coding scheme. 

Field surveys 

● The survey plan is developed prior to the field survey. Sampling is based on 

transects perpendicular to the shoreline. 

● The coordinates of the sampling station are listed for Global Positioning System 

(GPS) referencing in the field. 

GIS data base revision 

● Data acquired in the field can be incorporated into corresponding layers in 

the GIS data base. Furthermore, data collected in on-going surveys in the 

context of other projects can be used to continuously update the GID data 

base. 

Publication and dissemination 

● A special publication could be produced in explaining the methodology used 

to establish coastal aquaculture zones. This can be done by presenting maps 

indicating appropriate zones for different species. 

Incorporation into CZM regulations 

● Zoning will only be effective if it is incorporated into CZM regulations. 

● When the eastern and northern coasts become accessible for development, 

there may be a "shrimp gold rush" to the area. When this occurs, it will be 

imperative to control development 

References 

Angell, C.L. 1998. A Manual for Coastal Aquaculture Zoning in Sri Lanka. FAO. 

Central Environmental Authority/Euroconsult. 1994. WCP in Sri Lanka – Wetlands

are no Wastelands. 

Ministry of Forestry and Environment Sri Lanka. 1999. Biodiversity Conservation of Sri 

Lanka. A Framework for Action. 

Prepared by: 

R. K. U. D. Pushpakumara

Successful Small-Scale Mudcrab Farming 

Development in the Thai Binh Province, Vietnam: 

A Case Study 

Mangrove or edible mud crabs (genus Scylla) are commonly found within the Indo- 

West Pacific region, where they inhabit tropical and sub-tropical mangrove areas. 

They have a high economic value due to their large adult size and high meat 

content. They, particularly the gravid female (also known as "egg crab") which are 

valuable in many countries, are fished principally for the export market. 

Mud crab farming has traditionally been a small-scale activity throughout Southeast 

Asia, most likely originating from fishermen retaining small numbers of undersized 

crabs in order to increase their market value. In Vietnam, mud crab culture became 

established since about ten years ago. 

Thai Binh Province is one of the coastal provinces on the fringe of the southern part 

of the Red River Delta (20o30’N; 106o34’E). Its coastline is composed of lower mud 

flats, mangroves, upper mud flats and small sand islands located within the river 

mouths. 

At present, 70% of families in Thuy Hai commune (mainly former soldiers and

fishermen) farm mud crabs in coastal ponds in Thai Binh Province, Vietnam. Even as 

a spare time activity, crab farming helps boost income significantly. 

Crab farms and production cycle 

Mud crabs are farmed in earthen ponds. These ponds can vary in size from as small 

as 1,200 m2 , where the ponds are artificially stocked, to 50 hectare ponds for 

extensive culture where the crabs are introduced from the inflow water with some 

additional small crabs purchased from fishermen. These extensive ponds also trap 

and hold other aquatic products including wild shrimp, fish and are often ‘planted’ 

with seaweed. 

Majority of aquaculture ponds are situated in front of the main sea dike but behind a 

recently planted area of mangrove trees (the trees are five to six years old) that act 

as a buffer zone against typhoons. The water quality is guaranteed to be much 

better in front of the sea dyke particularly since a large number of the farms rely on 

tidal water exchange. Over the last four years, coastal aquaculture has become 

more developed and formerly large extensive ponds have been subdivided into 

smaller, semi-intensive operations. 

All ponds have a simple sluice gate for water exchange and are surrounded 

by some form of fencing to prevent the crabs from escaping. 

Reasons for successful development of mud crab farming in Thai 

Binh Province

The success of mud crab farming development in the area are due to several 

reasons. 

Site suitability 

The coastal mud flats within Thai Binh Province are accreting rapidly. Every five years, 

about 250 to 300 ha of "new coastal land" are formed. This new land is suitable for 

pond construction and has good access to coastal water supply. 

Water supply 

The freshwater input from the Red River results in brackish water conditions ideal for 

coastal aquaculture. Moreover, the level of local water pollution is low due to lack of 

urbanization and agriculture in the immediate area. 

Accessibility 

Sea dikes not only protect local villages against storm damage, but also provide the 

main road system between neighbouring communities. Seed, feed and harvested 

aquatic products are transported without difficulty. The sea dike also serves as focal 

trading point where traders, farmers and fishermen can trade mud crab. 

Seed and feed supply 

The mangrove protection belt provides the habitat for juvenile mud crab as well as 

other aquatic species. This has resulted in an increase in juvenile mud crab caught in 

stock ponds providing plentiful seed supply to support mud crab farming. Moreover, 

food sources for aquaculture such as low value fish species, small mangrove crab 

species and mollusks, are abundant in the mangrove buffer zone. 

Socio-economic factors 

Strong community–based structure, along with the entrepreneurial spirit and hardworking 

attitude of the local people, has created the opportunity for many coastal 

communities to benefit from crab farming. The direct beneficiaries from aquaculture 

tend to be to the more wealthy and enterprising sectors of the community who can 

afford to invest in mud crab culture. However, the poorer fishers can also benefit 

from collecting crab seed and food materials to sell to the crab farmer and by 

providing labor for many aspects of pond operation: building and repairing of 

ponds, harvesting, guarding against poachers etc. Hand collecting of juvenile mud 

crab from the mangrove is carried out mainly by women and sometimes children. 

Both men and women, young and old, are involved in buying and selling crab, either 

as primary or secondary dealers. These additional activities spread the economic 

benefit of crab production widely within the community.

Technical knowledge base 

The combination of the knowledge gained about tidal water management from salt 

making and the fishers’ understanding of local aquatic resources means that the 

progression to aquaculture was a fairly easy one. In addition, local government 

initiatives to promote aquaculture through technical workshops organized at the 

district and commune level have resulted in the training of local people in various 

forms of coastal aquaculture, in particular shrimp and crab farming. 

Adaptability of mud crab farming to other regions 

Mud crab farming could be replicated successfully in other regions for the following 

reasons.

● Mud crabs are suitable for local market 

conditions (easy to move, store and 

trade) and the export market potential is 

excellent. It represents another high 

value crustacean product on the market 

and prices come close to those of 

farmed shrimp. 

● Earthen ponds can be used to culture 

either mud crabs or shrimp depending 

on the economic climate, requiring little 

cost in modifying the culture system. 

● Mud crabs are hardy animals. They can 

withstand salinity fluctuations and low 

oxygen levels within ponds. As long as 

they are kept in cool and moist 

conditions, survival out of water for two 

to three days is probable. Transporting 

individually tied mud crabs from the 

pond site to markets is easy and simple. 

Potential constraints associated with mud crab farming 

Some limitations may affect the replication of crab farming to other areas. 

● Different mud crab species may have slightly different biological requirements 

that may affect the way they are cultured. 

● Currently, mud crab culture is still in its infancy 

and mud crab farming still relies on seed supply 

caught in the wild. For the small-scale farmer, 

locally caught seed supply is vital for 

sustainability of crab farming, although they only 

require a few crabs to sustain their small-scale 

activities. A sudden and uncontrolled increase in 

mud crab farming for other practices such as 

soft shell crab farming could have a devastating 

effect on wild mud crab stocks through over exploitation. Moreover, the 

overfishing of juveniles may eventually affect the number of adult crabs 

available for other fisherfolk. 

● The high value of mud crabs means that they are farmed primarily as a cash 

crop rather than as a protein source. The increasing commercial interest in 

mud crab farming may result in a rapid expansion of the sector. This expansion 

could cause problems, like competition over land, pollution and disease due 

to over development and/or lack of coastal planning, as has been observed 

widely in the shrimp industry. 

● The low-cost fish used to feed crab might be better used to provide food for 

the poorer sectors of the community. Other potential protein sources need to

e investigated. 

Further reading 

Angell, C.A. (editor). 1992. The Mud Crab: A Report on the Seminar Convened in 

Surat Thani, Thailand, November 5-8, 1991 (BOBP/REP/51). Bay of Bengal 

Programme, Madras, India. 

Keenan, C.P. and A. Blackshaw. 1999. Mud Crab Aquaculture and Biology. 

Proceedings of an international scientific forum held in Darwin, Australia, 21-24 

April, 1997. ACIAR Proceedings No. 78, 216p. 

Overton, J.L. and D. J. Macintosh. 1997. Mud Crab Culture: Prospects for the Smallscale 

Asian Farmer. Infofish International, 5/97, 26-32. 

Prepared by: 

Julia Lynne Overton and Donald J. Macintosh

Management Practices to Improve Extensive 

Shrimp Aquaculture 

Low yields due to low survival rates and frequent disease conditions are main 

problems encountered in extensive shrimp culture. A greater part of production 

losses occurs soon after stocking of post-larvae because of unsuitable conditions in 

the pond. The following management practices are recommended to reduce poststock 

losses and increase production, particularly for black tiger prawn. These 

recommendations are based on the results of the project "Disease prevention and 

health management of coastal shrimp culture in Bangladesh". 

Select the correct season for stocking shrimp fry 

Shrimp post-larvae are sensitive to climatic changes. Low yields and disease have 

been experienced when shrimp post-larvae are stocked during rainy or cold months. 

During cold months, temperature fluctuation in a day usually exceeds 2ºC. 

Temperature less than 20ºC causes harm to shrimp post-larvae. Other reasons for 

avoiding the rainy season are: 

● Sudden salinity decline in water is very stressful to shrimp post-larvae.

● Low salinity affects the molting process resulting in slow growth. 

● Heavy loading of silt and suspended solids increases sediment accumulation 

(leading to depletion of oxygen in the water). 

In establishing the pond, remember the following. 

Establish a nursery pond 

A nursery pond will provide a predator- 

and competitor-free environment to 

enhance the survival of post-larvae. 

Supplementary feeding of shrimp fry in 

the nursery will be more effective than 

feeding the post-larvae in the main 

pond. 

● A 0.4-ha nursery compartment pond should be set aside within a 6-ha pond. 

● Larger ponds should have two or more nursery compartments rather than one 

big nursery compartment. 

● Do not stock more than 20 to 25 post-larvae per square meter. 

Nursery preparation before stocking 

1. Dry the pond bottom thoroughly to reduce organic waste load and remove 

predators and competitors that entered the pond during the previous culture. 

Take note of the following: 

● After drying the pond, scrape 

the surface of the pond 

bottom to remove the waste. 

When scraping, avoid 

exposing the subsoil, which 

may contain acid sulphate 

layers. 

● Avoid waste accumulation 

on pond dikes. Remove and 

dispose of accumulated 

waste away from the pond so 

that the rain will not wash it 

back into the pond.

● Dry and wash the pond bottom again after scraping and plowing. 

2. Apply lime to the pond to 

correct the soil pH and neutralize 

the acidic layer in the pond 

bottom and dike surface. Liming 

will also disinfect the pond. 

Spread lime all over the pond 

bottom, applying more on areas 

that remain wet. Also spread 

along dike walls up to the top of 

the dike. 

Agricultural lime or dolomite is 

better than hydrated or quick 

lime because of its buffering 

action that can regulate the 

pond pH. Always remember to 

use the right amount of lime. 

3. After liming the pond bottom, fill the pond with 30 cm of water and add 

fertilizer. It is necessary to fertilize the pond water to grow natural food (plankton) 

in the water. Some common fertilizers used are: 

– inorganic fertilizer: urea and trisuper phosphate (TSP) 

– organic fertilizer: cowdung

The usual fertilization amounts are as follow. 

– First application: 1 kg of urea and 1 kg of TSP or 6-10 kg of 

cowdung per ha. 

– Before the second application, leave the pond for 3-4 days until 

the pond water turns greenbrown in color. 

– Completely fill the pond with water. 

– Second application: 1 kg urea and 1 kg TSP per ha each day for 

5–7 days or 6–10 kg cowdung per ha every 2–3 days for 12-15 days. 

– Do not apply cowdung daily because it is slow acting; daily 

application might overfertilize the pond. 

– Applying more fertilizers if the pond water does not turn greenbrown. 

As a last resort, add some green water from a known pond. 

4. Control the entry of predators and competitors. The practice of stocking shrimp 

post-larvae into ponds containing other species favors predation soon after 

stocking, thus, causing significant production losses. To avoid this, do the 

following. 

– Screen the incoming water through a nylon net screen with 576 

holes per square inch or 24 holes in a linear inch. 

– Use two net screens: a straight net screen fixed into a frame and 

placed in the gate at the outer side of the pond and a filter bag net 

screen (2 - 3 m long) fixed into the gate at the inner side of the pond. 

Provide supplemental food for post-larvae 

Supplemental food helps increase the survival and growth of shrimp before being 

released into the main pond. Large and healthy shrimp can avoid predation and 

withstand unfavorable conditions in the main pond. 

Use the best quality feed that can be afforded. Own preparation of supplemental 

food would be advantageous, especially if available commercial post-larval feeds 

are too costly. 

Supplemental food 

● Use chopped fish, rice bran and cooked rice or potato. Mix the ingredients, 

using the following percentages: 

Ingredient Percent by weight 

Whole fresh fish 50-60 

Rice bran 20

Cooked rice/potato 20-30 

● Mash all the ingredients and rub through a sieve in small bits (2 mm in 

diameter). If shrimp fry are large enough, use larger pieces about 4 – 5 mm 

diameter. 

● Sun dry the feed for six hours before using. 

● Do not use shrimp, mussel, clam or cockle meat as it might transmit virus 

infections. 

The following daily food amounts are recommended for a nursery stocked with 20-25 

post-larvae/sq m: 

Feeding 

Period (days) Feed per day (kg) Expected survival (%) 

1–7 0.8-1.4 100-86 

8–14 1.5-2.2 84-71 

15–22 2.4-3.2 70-63 

23–30 3.3-4.1 62-60 

● Feed four times a day, preferably between 7-8 a.m., 11 a.m. to 12.00 noon, 4-5 

p.m. and 10-11 p.m. 

● Feed 25% of the daily food ration on each occasion. 

● Dampen the food before adding into the pond. 

● Spread the food in an area not more than 2-4 m from the slope of the dike, as 

this is where healthy post-larvae usually stay. 

Perform regular health checks on shrimps 

There are two ways to perform health checks during culture: 

1. observation from the dike; and 

2. observation of sampled shrimp. 

Observation from the dike 

Observation of sampled shrimp 

● Avoid doing the observation during hot afternoons as handling would stress 

the shrimp. 

– Make the observation fortnightly. 

– The following conditions would indicate that the shrimp is normal. If

anyone of them is not observed, then there might be a disease 

problem. 

Characteristics of a normal and healthy shrimp 

● Appendages are clean. 

● No blackening of appendages. 

● Tail is not swollen or eroded. 

● The body color is greenish cream. 

● The body is clean and shiny. 

● The shell is not soft or does not crack easily. 

● The gills are clean, shiny and has a cream color. 

● Hepatopancreas has a yellowish green color, not shrunk or enlarged. 

Prepared by: 

P. P. G. S. N. Siriwardena and Anwara Begum Shelly

Farmers’ Methods of Oyster and Mussel Culture in the 

Philippines 

Oyster and mussel farming can be a source oflivelihood for 

coastal communities. Though it may not be the main source, it 

can contribute significantly to household income and food. 

Women and children can also participate. Oysters and mussels 

are delicious and very good sources of protein, carbohydrates, 

vitamins and minerals, and thus have good market value. 

In the Philippines, the cultured species are the slipper-shaped 

oyster (Crassostrea iredalei) and the green mussel (Perna viridis). 

Several culture methods for oyster and mussel farming have been 

reported but only a few deal with the farmers’ methods. The 

culture methods described here are based on farmers’ practice 

and are farmer-proven. 


Oysters and mussels grow in brackish and salt-water areas. 

Specifically, oysters grow well in estuaries where salinity is lower due to the mixing of fresh and seawater. 

Mussels grow better in bays where salinity is higher than in estuaries. Oyster farms are generally located 

in shallower areas than mussel farms. 

Characteristics

Seed collection 

Presence of a natural population of oysters or 

mussels. This makes seed collection and 

growing easier and inexpensive. In areas where 

there is no natural population, seeds may be 

collected from other places and transplanted 

for growing. 

Good growth of wild or farmed oysters or 

mussels in the area. This indicates the 

abundance of natural food and the feasibility 

of farming oysters or mussels. 

Proximity of farm site to residence for easy 

monitoring and guarding against poaching, a 

big problem among farmers. 

Water current for the transport of food, waste 

and silt. 

Availability of farm site (without obstructing 

navigation). 

Protected from strong winds and waves to 

avoid damage to farm structures. 

Free from domestic and industrial pollution. 

Seeds are collected directly using substrate materials such as empty oyster shells, 

or the bamboo poles used in growing oysters or mussels. 

By experience, farmers know the periods when seeds are abundant in the area. In 

Western Visayas, farmers reported using some indicators such as the presence of 

barnacles on the substrate materials as this would be followed by attachment of 

oyster or mussel seeds. The water also becomes itchy, yellowish with lots of 

bubbles. 

These indicators are difficult to explain but they may be related to seasonal 

change. According to oyster farmers, the seeds are abundant when seawater mixes with freshwater in 

the estuary during full or new moon. 

The presence of seeds is checked through ocular inspection of the substrate materials to see whether 

their surfaces have become rough with the presence of grain-size spots. 

When culture is developed in a new area, a careful observation for a year or two will reveal the local 

seasonal pattern. Abundance of mussel seeds is pronounced during certain months of the year 

depending on the locality. Oyster seeds are generally available throughout the year. 


Most oyster farmers learned the culture methods from other farmers in their neighborhood. They imitate 

the culture method that has been found productive and profitable by other farmers.

Oyster 

The methods commonly used for oyster culture are bottom, stake and hanging either from a rack or raftrack. 

The stake method is the most commonly used but the hanging method is the most productive 

followed by the stake then the bottom method. Bottom and stake methods are used in shallow 

(intertidal) areas, whereas the hanging method is used in deeper areas. 

Bottom 

This is a natural way of growing oysters. This method is suitable for intertidal areas (exposed during low 

tide) or areas where structures obstructing boat navigation are not allowed. 

In this method, empty oyster shells are scattered or broadcast to serve as substrate for oyster seed to 

attach to and grow on. This method may be the least costly but mortality due to siltation and predators 

is very high. 

Stake 

In stake method, farmers use one or a combination of different materials such as bamboo (Bambusa 

spp.), mangrove tree branches and nipa petioles. 

Stakes are about 2 m long with 0.6 m embedded 

in the bottom. They are placed 0.7 m from each 

other and are usually arranged in rows 0.8 m apart.

Procedure 

1. Construct a raft using bamboo poles with spacing of 

20 cm. 

Rack hanging 

2. Stake the bamboo poles on the four corners to set the 

position of the raft-rack. 

3. Hang the strings of empty oyster shells from the raft at 

about 20 cm apart. The string of empty oyster shells 

should be about 1 m long, depending on the water 

depth at low tide. More hangings may be placed on the 

raft but other hangings are transferred to additional rafts 

in the later part of the culture period. 

Racks are usually made of bamboo poles 

although some farmers use wood. Racks may be 

as high as 4 m and 1 m apart for easy boat 

navigation during monitoring and harvesting. 

Empty oyster shells are strung at a distance of 

about 20 cm from each other(1.4 m long) and 

hung from the rack. On a nylon string, empty shells 

are spaced at 14 cm from each other by knots. 

Some farmers use old tires (halved or whole) of 

motorcycle, bicycle, truck, or jeepneys as 

hangings. 

Raft-rack hanging 

Many oyster farmers do not adopt the raft method 

recommended in many literatures because it 

requires artificial floats and is, therefore, expensive. 

However, based on the survey, farmers use a less 

expensive raft made of bamboos only. Called the 

raft-rack method, this is a modification of the rack 

that floats during the early stage. 

4. Allow the raft to float and adjust it according to water level for the first two to three months. 

Thereafter, when the oysters are too heavy for the raft, tie the raft to the bamboo posts at 1-3 m 

above the bottom, depending on the water depth. 

5. Stake additional bamboo poles to further support the heavy raft.

Mussel 

Mussels are cultured by bottom, stake or raft method. The stake and raft being off-bottom methods are 

used in relatively deep waters (2-4 m at low tide and 5-8 m at high tide), while the bottom method is 

used in shallower areas (0.60 m at low tide and 3.6 m at high tide). 

Bottom 

This method of growing green mussel is not reported in other 

literatures but it is used by farmers in a certain locality where the 

seed collection site is far from their residence. Since growing the 

mussels in the same area could result in poaching, mussel seeds are 

collected from the bay using bamboo poles. After one to two 

months, the mussels are removed from the bamboo poles and laid 

at the bottom of estuary near the farmers’ residence. 

Stake 

Bamboo is the most commonly used material in the stake culture of the green mussel. Some farmers use 

a combination of bamboos, coconut fronds and nipa petioles. Others attach old fish nets to their stakes.

Some variations of the stake method 

Raft 

The manner of staking differs according to water depth 

and strength of water current in the farm site. In areas 

where the water current is strong and the farming area is 

deep, full-length bamboos (10 m) are staked 1 m apart 

and tied to 3-5 layers of horizontal braces. In other farming 

areas where water is not so deep and water current is not 

so strong, bamboo poles are simply staked without being 

tied to horizontal braces. 

Raft culture of the green mussel differs from the usual system, which uses floats, anchors and hangings. 

Farmers use a different and less expensive raft made of several bamboos, which serve both as seed 

collector and substrate for growing, but 

without hangings. 

The raft is allowed to float within the 

confines of the bamboo posts during the 

first two to three months. Thereafter, 

when the mussels become too heavy, 

the raft is tied to posts at a fixed position 

in the water. Additional posts may be 

added to further support the heavy raft.

Maintenance and management 

Bed degradation (i.e., sedimentation), pollution (domestic or pond 

chemical effluents), occasional lack of seeds (especially for 

mussel), and biofouling (attached organisms) are some problems 

reported by oyster and mussel farmers. Many farmers admitted 

that sedimentation is primarily caused by their farm structures, 

particularly stakes. Their solutions to these problems include: 

● removing stakes after harvest or moving the raft to another 

available space (but very few farmers do this); 

● cleaning or removing biofoulers such as sponges, barnacles, 

filamentous algae (more mussel farmers do this than oyster 

farmers); and 

● maintaining broodstock (big oysters or mussels) in the farm to ensure a steady supply of seeds. 

Some farmers remove some oysters or mussels in overcrowded substrates to allow faster growth of 

remaining oysters or mussels. Removed oysters or mussels are either marketed or transferred to another 

growing area or substrate. 

Harvesting and post-harvest practices 

Oysters are harvested when they are 7-8 cm (3 

inches) long or 10-12 months after seed 

collection. But harvesting can also be done at six 

to eight months, if oysters have good growth. On 

the other hand, mussels are harvested nine to 12 

months after seed collection. 

Oysters and mussels cultured using the bottom 

method are harvested during low tide by taking 

them from the muddy bottom and placing them 

inside a sack. In stake culture method, bamboo 

poles are pulled and hauled to the boat or raft 

where the mussels are scraped off using a bolo 

(large knife) or boat paddle. In hanging method, 

the strings of oysters are simply removed from the 

rack and placed in the boat for subsequent cleaning and washing. However, if harvesting is partial, big 

oysters are removed from the clusters using a bolo. Mussels cultured using raft method are harvested by 

cutting the ropes assembling the raft, hauling the bamboos to the harvesting raft with net flooring, and 

scraping off the mussels using either a paddle or bolo. 

Harvested oysters or mussels are cleaned by 

placing the harvest in a basket, sack, or screen 

nets and shaking them underwater (seawater) 

to remove mud, algae and other attached 

organisms. Cleaning tools such as brush or bolo 

are also used to scrub and scrape attached 

organisms. After cleaning the oysters and 

mussels, sorting by size is done to make it easier 

for the buyer to price the products when 

reselling to market retailers.

Conclusion 

Marketing 

Oysters and mussels are sold either as: 

shell-on fresh; 

shell-on cooked; 

shucked (meat removed from shell) fresh; and 

shucked preserved. 

Shell-on fresh is the most preferred form by buyers 

who are mostly household consumers and 

restaurant owners. The buyers can then choose the 

kind of cooking desired by family members or 

customers. 

In oyster culture, the raft-rack hanging method gives the highest yield and income compared to rack 

hanging, stake or bottom method whereas in mussel culture, the stake method gives better results than

the raft method. 

Farmers’ methods of oyster and mussel culture by raft-rack hanging and raft methods, respectively, are 

productive methods, which have not been sufficiently documented in other literatures.

Mud Crab Systems for Small-Scale Aquaculture 

Mud crab farming has traditionally been a small scale 

activity, originating in China over 100 years ago and 

spreading across Asia over the last 40 years. Its close 

affinity to coastal mangrove areas within the Indo- 

West Pacific limits mud crab fishery to coastal, 

artisanal style fishing. It was, therefore, natural for 

fishermen to improve the value of their catch by 

retaining both underweight and juvenile crabs for 

rearing purposes. As a family level occupation, mud 

crab farming proved to be quite profitable, provided 

there was a sustainable seed supply from the local 

fishery. 

The traditional trade in mud crab has been for hardshelled 

crab products, namely meat crab and egg 

crab. However, in recent years the market for mud 

crab products has extended to soft-shell crab and 

processed crab meat.

Two types of meat crab culture 

1. Fattening 

This is the holding of fished crabs that have recently molted 

(also known as thin or "watery" crabs) for 10 - 30 days until 

meat weight has increased. 

2. Grow-out 

Meat crabs are the only mud crab product 

most applicable to small-scale aquaculture. 

The other products require high investment 

both in terms of technology and food supply. 

Also, there are environmental considerations 

with soft-shell and egg crab farming, as they 

tend to exploit parts of the natural crab 

population that are most sensitive to 

overexploitation by requiring a high turnover of 

juvenile and pre-spawned females, 

respectively. For these reasons, the rest of the 

paper will concentrate on production of meat 

crab. 

This is the process of stocking juvenile crabs (10 g to 100 g) and allowing them to molt and 

grow. Harvest is after 3-8 months or once the crabs reached 200 g to 500 g size. 

Mud crab fattening is the most suitable for small-scale aquaculture because: 

● Turnover is fast, hence, the period between investment and returns is short. 

● Fattened crabs can be stocked at higher densities (15 crabs/sq m) compared to growout 

systems (1 crab/sq m) as no molting occurs and therefore losses to cannibalism are 

dramatically reduced. 

● Short production time reduces the risk of losing crabs to disease, thus, rendering a 

higher survival rate for fattening (>90%) compared to grow-out systems (40%). 

In addition, crabs can be traded in small numbers as mud crabs are valuable as individual 

animals. This means that farmers can hold small numbers of mud crab at a moderate 

stocking density and still make a reasonable profit. Meat crabs can be farmed in ponds, 

cages and pens both using the fattening or the grow-out systems of stocking and harvesting. 

General considerations 

Seed supply 

At present, hatchery-produced mud crab seeds are not widely available. Therefore all crabs 

used to stock the mud crab systems are caught by the systems’ operators themselves and/or

are bought from local fishermen. 

Feed 

Mud crabs are carnivorous and scavengers. In all cases, the mud crabs are fed with locally 

caught fish species, which have a low market value. These low value fish species are 

harvested by the mud crab farmer themselves or are bought locally from other fishermen. 

Pond culture 

Earthen ponds are most commonly used in small scale culture of mud crab. Small ponds are 

built in the homestead (200 sq m or less). Farmers usually build a fence around the perimeter 

of the pond to prevent crabs from escaping to keep away predators. The fence can be 

made of a range of materials, e.g., roofing tiles (Vietnam), concrete slabs (Sri Lanka), 

polyethylene sheets (Philippines) or mesh (Vietnam/Thailand). A simple sluice gate is used to 

allow water exchange. The method of stocking, feeding and harvesting as well as the level 

of pond maintenance varies widely from farmer to farmer. The example below is of a very 

simple system observed in Surat Thani province, Thailand 

Cage culture

Cage culture of mud crab makes use of estuaries, lagoons 

and brackishwater ponds. Floating cages, made of 

bamboo or polyethylene/galvanized wire net, are mainly 

used for mud crab fattening. The cage culture of mud 

crabs has been used in the Philippines and Indonesia. 

These cages can include those that are divided into 

compartments for individual crabs, thus reducing the 

mortalities due to aggression and cannibalism. The cages 

are floated using plastic floats and empty oil barrels to 

keep the upper side at surface level. A mesh screen is 

needed on top of the cages to prevent the crabs from 

escaping. Cages will allow individuals who do not have 

access to land to farm mud crab. 

Pen culture 

Pen culture has been used for grow-out of mud crab in the 

Philippines and Sarawak, East Malaysia. This method 

integrates the system of crab rearing with the coastal 

mangrove forests, which does not involve the clearing of mangroves to construct ponds. 

Instead, the mangrove forest is penned-off and stocked with crabs. The pens can be made 

of plastic netting supported with a bamboo network (as in the Philippines) or made of wood 

(as in Sarawak). They rely on tidal water exchange and supplemental feeding. Pens for 

culturing mud crabs may also be constructed within ponds and shallow rivers.

Integrated culture of Scylla 

The mud crab has been shown to be a good polyculture species, particularly with finfish 

species (milkfish and Tilapia) and seaweed (Gracilaria). An example of this is in the Thai Binh 

Province, North Vietnam. Mud crabs also have the potential to be farmed in coastal rice 

fields during the dry season. 

Advantages of mud crab culture 

1. Mud crab is a high-value species and its culture can significantly increase the income of 

rural coastal communities. 

2. The technology required to culture crab is relatively uncomplicated (this refers mainly to 

ponds and pens) and can be easily disseminated to farmers. 

3. Previously abandoned shrimp pond areas can be conv 

erted for crab culture with relatively little additional conversion costs, e.g., fencing to prevent

the crabs escaping from the ponds. 

4. The mud crab has an international market (e.g., the restaurant trade in Singapore, Hong 

Kong, Bangkok and Taiwan) therefore the culture generates much needed foreign 

exchange. 

5. Unlike exotic species, the mud crab is indigenous to the Indo-West-Pacific, therefore its 

market trading system is already well established within the region from fished mudcrab 

products. The transition to also include farmed crab will be relatively easy. 

6. Transportation of mud crab is very simple. Individually tied mud crabs are transported in 

damp conditions in baskets from the pond to the market place. Moreover, crabs can be 

transported and stored in this way for three to 

four days. 

Rice/crab farming in Tra Vinh Province, Vietnam 

Both crab growout and crab fattening are practiced in rice fields in Tra Vinh 

Province. In both cases, minor modifications are made to the rice fields, namely 

installing a mesh net around the perimeter or the area that is being used to farm 

crabs and deepening the waterways. 

The grow-out system is an extensive system where the crabs are stocked and 

harvested but there is no supplemental feeding involved. Fattening requires feeding 

to improve the weight of the crabs in a short period of time; low-cost fish species are 

used to feed the crabs. 

The grow-out systems proved to be the more profitable as smaller crabs, which were 

cheaper, were used to stock the ponds and there were no feed costs. However, 

survival was low in the extensive system, mainly due to cannibalism. Both systems 

are family run, extra labor only being employed during the harvest season. 

This system is profitable as long as the salinity levels are kept low to 

ensure a good rice crop. It also helps farmers save money by avoiding 

the use of pesticides, which are detrimental to the health of the mud 

crabs. 

The species of mudcrab found is S. paramamosain. It does not burrow, 

therefore, does not affect pond infrastructure.

7. Mud crab farming also involves other sectors of the community who do not have the 

capital or the land/water access to start crab farming themselves. These people may be 

involved in collecting food items or crab seed, providing labor for pond maintenance and 

guarding and harvesting of ponds, as well as transport of harvested crab to the 

marketplace. 

8. The link between the mud crab and the mangrove provides an incentive to preserve the 

mangrove resource. 

Constraints of mud crab culture 

1. A fundamental pre-condition for the future sustainability and expansion of the mud crab 

industry is a reliable seed supply, particularly in soft-shell crab farming, which has a high 

turnover of juvenile crabs (~ 80g each). Ongoing research into hatchery production of mud 

crab is starting to produce reasonable survival rates of crab seed. However it is still not on a 

scale that can be deemed economically viable. Thus, the expansion of mud crab farming is 

constrained by the availability of seed supply from the wild. 

2. Crabs can suffer high mortalities from diseases similar to those that affected shrimps. 

3. Although pen and cage cultures have been shown to be suitable for mud crab 

production, the majority of mud crab is cultured in ponds. This means that any expansion in 

mud crab farming is going to be influenced by the same issues that faced the shrimp

industry, including competition for coastal sites for ponds and pollution from over 

development. 

4. The high value of mud crab makes it very attractive to richer sectors of the community 

and in some cases outside investors. This can marginalize the poorer households and prompt 

them to use less suitable locations to farm crab. 

5. There may be competitition for locally caught low-value fish species that could be protein 

sources for the poor members of the community. This potential conflict needs to be outlined 

and efforts are needed to find alternative sources of crab food. 

Conclusion 

Mud crab culture is suitable to small-scale farmers as hardy and high value crabs can 

improve the income of the household even when small numbers are farmed in very simple 

culture systems. Soon hatchery-produced seed will be available to farmers, substantially 

reducing fishing pressure on wild crab stocks. 

Reference 

Keenam, C. P. and Blackshaw, A. 1999. Mud crab aquaculture and biology. Proceedings of 

an international scientific forum held in Darwin, Australia. April 21-24, 1997. ACIAR 

proceedings No. 78. 216 p. 

Prepared by: 

Julia Lynne Overton and R. K. U. D. Pushpakumara

Small-Scale Seabass Culture in Thailand 

Seabass or giant sea perch (Lates calcarifer) has been cultured in Southeast Asia in marine, 

brackish and freshwater areas. This species is widely distributed in the tropical and subtropical 

areas of the Western Pacific and Indian Ocean. Its range of distribution includes Australia, 

Southeast Asia, Philippines and countries bordering the Arabian Sea. Seabass culture in 

Thailand is still small-scale compared to marine shrimp culture. The market for marine shrimp is 

global, while the market for seabass is largely regional. 

Advantages of seabass as a species for aquaculture 

● Can tolerate wide range of salinity from freshwater to 35 ppt making it suitable for 

aquaculture in estuaries, river mouths, inner bays and mangrove swamps where the 

salinity condition is unstable 

● Feeds and grows well in high turbid waters 

● Fast growing 

● Can tolerate high density conditions and handling stress 

● Easily tamed for aquaculture conditions and accepts either fish flesh or artificial feeds 

● Availability of eggs/fry in commercial quantities 

Spawning of seabass 

Two major techniques are employed in mass 

production of seabass fry: artificial fertilization 

and induced spawning. 

Artificial fertilization 

● Spawners are caught in natural spawning grounds where the water depth is about 10- 

20m. 

● The degree of maturity is immediately checked. 

● The unfertilized eggs are stripped directly from the female. 

● The eggs are then placed in a dry and clean container with clean seawater and milt is 

added. A feather is used to mix the milt and eggs.

● Clean sea water is stirred into the mixture, which is then left for five minutes. 

● The fertilized eggs are transported to the hatching tank. 

Induced spawning 

Two methods are normally used for inducing seabass to spawn in captivity: hormonal injection 

and environmental manipulation. 

Induced spawning by hormone injection 

● Seabass brooders are stocked in the pre-spawning tank for 

two months. The fishes are checked twice a month during 

spring tide. 

● A polyethelene cannula is used to sample eggs from the 

female broodstock. 

● The fish is either anesthetized or inverted gently with the 

black hood over the head. The cannula is inserted 6-7 cm 

into the oviduct.Eggs are sucked orally into the tube. 

● The female is ready 

for hormone injection 

when the tertiary yolk 

stage (egg diameter 

0.4 - 0.5 mm) is 

reached. 

● Spawners maybe 

injected 

intramuscularly below 

the dorsal fin with the required hormone dosage. 

● The fishes are transferred to the spawning tank and are expected to spawn within 12-15 

hours after injection. 

Induce spawning by environmental manipulation 

Steps in stimulating seabass spawning in 

captivity: 

1. Change the water salinity to simulate fish 

migration. 

2. Decrease the water temperature to 

simulate the decreased water temperature 

after rain. 

3. Lower and subsequently add seawater 

to the tank to simulate the rising tide and 

the moon phase. 

At the beginning of the new or full moon, the water temperature in the spawning tank is 

manipulated by reducing the water level to 30 cm deep at noontime and exposing it to the sun 

for two to three hours. This procedure increases water temperature in the spawning tank to 31- 

32ºC. Filtered seawater is then added to the tank to simulate the spring tide. In effect, the water

temperature is drastically decreased to 27-28ºC. The fish spawn immediately the night after 

manipulation. If no spawning occurs, manipulation is repeated for two to three more days, until 

spawning is achieved. 

The fish will usually spawn for three to five consecutive days. Since seabass spawn intermittently 

by batch, the same spawners will continue to spawn during full moon or new moon for the next 

five to six months. 

Larval rearing 

Rearing tanks 

● Fabricated from plastic, fiberglass, wood or concrete 

● Rectangular or round shape 

● Located outdoors, protected from strong heat and heavy rains by a roof tile cover 


● Newly-hatched larvae density in rearing tank is between 30-100 larvae/liter 

Feeds and feeding 

● Green water (Chlorella or Tetraselmis) is added on the first day of rearing to maintain 

good water quality. 

● Beyond three days, rotifers are introduced as feed and are maintained at a density of 

three to five rotifers/liter with green water. 

● Under developing stages (ten-day-old larvae, juvenile and subadult), artemia and

Grading 

minced fresh fish are available on demand. 

● Grading of size is needed for homogeneous growth and to minimize losses due to 

cannibalism. 

● This process is done a week after the larvae have started to feed on artemia and every 

week thereafter. 

● Grading trays used are made of plastic with many holes. 

● Each tray has specific hole or mesh size which ranges from 0.3 - 10 mm. 

Nursery 

● Fry from the hatchery are 

cultured. 

● Solves the problem of 

space competition. 

● Increases the fry survival 

rate. 

Types of cages 

In general, the 

size of a square or 

rectangular cage 

ranges from 20 to 

100 m3. The 

cages are hung 

from floating 

wooden or 

bamboo frames 

using styrofoam 

blocks or 

polypropylene 

tubes fastened to 

poles and set in 

shallow waters. 

The fish is mostly 

fed with chopped trash fish, the amount of which is 5-10% fish weight/day, with a stocking 

density of 10-40 fish/sq m. 

Floating 

The net cages are attached to wooden or bamboo frames. The cages are kept floating by 

materials such as plastic, styrofoam drum or bamboo. The shape of the cage is maintained with

the use of concrete weights 

attached to a corner of the cage 

bottom. Floating cages are suitable 

in areas where the water is more 

than 2 m deep and the tidal 

fluctuation is wide. 

Floating cages are more popular 

because these are: 

● usually placed in sites with 

better environmental 

conditions; 

● generally located at greater 

distances from pollution sources; and 

● these can be stocked with more fish than stationary cages. 

Stationary 

Stationary cages are fastened to bamboo 

or wooden poles installed at its four corners. 

These do not move with tidal fluctuations. 

These are popularly used in shallow bays 

where tidal fluctuations are less than 1 m. 

Prepared by: 

Khorkiat Koolkaew

Coastal Aquaculture Options 

Small scale aquaculture in coastal areas has been slow to develop new approaches 

and spread existing technology in most countries. The developments that have 

taken place are largely with the investments of non-residents and are larger scale 

production systems like shrimp ponds and marine fish culture. The notable exceptions 

are oysters, mussels and seaweeds in a few countries. 

Aside from some seaweeds, mussels and oysters, most coastal aquaculture 

technologies have been aimed at moderately-high to high valued species. These 

species are too expensive for poor people to consume at home. The culture of high 

valued species entails considerable investment in the security of the crop, either for 

physical confinement or protection from theft. They are thus, for practical purposes, 

difficult for poor fishers to develop unless they have some existing infrastructure. 

In the following sections several species are presented with a brief description of 

culture methods used. Some of these are of moderate value and the culture 

technology may be adapted for species that might be used for family consumption 

or local markets. 

The presentations are meant to provide only an indication of the technology, the 

requirements and the potential. In most cases, there may be sufficient information 

for interested people to try the techniques with local adaptations of material, feeds 

and management. Before the details of particular species are presented some

general guidelines for coastal aquaculture development are discussed. 

General Guidelines 

Try it. Change it. 

The information provided here is designed to provide the basis for assessment of the 

practice and perhaps for preliminary trials. These methods have been used in other 

places but the many variations can not be shown. Fishers are encouraged to try 

alternatives, to make adaptations, and to monitor and evaluate the results. 

If you use a cage or pen, try culturing a few species together to make better use of 

the space. First attempts should be at low stocking density to ensure the 

compatibility of the species. Use your knowledge of species carefully as you do not 

want to introduce a species which will eat your main species! 

Tenure 

Perhaps the biggest constraint to developing aquaculture along the estuaries and 

marine coastlines is the lack of tenure. In most countries individuals are not permitted 

to "own" such areas. In only a few cases local governments (municipalities or 

villages) have authority to manage adjacent marine and estuarine waters. Even 

when local governments have legal mandates for control, they often lack the 

resources to enforce national or local fisheries regulations or to protect private 

property in the water. 

Social acceptance 

Under such circumstances it is difficult to 

establish aquaculture, which requires an 

investment and a growing period. Such 

investments are at risk during the growing 

period when crops are exposed to natural 

calamity (storm, floods, etc.) and to theft and 

vandalism.

Whether one has legal permission for an aquaculture 

venture or not, it is important that the activity is 

recognized by neighbors as an acceptable and 

worthwhile practice. Since coastal aquaculture is likely to 

develop in "our waters", in other words, water areas that 

have been traditionally used by multiple users, the 

traditional users of the area will have to support the 

changes. Peer pressure in a community is often the most 

effective means to enforce regulations and protect 

private property. 

Make the new options available to all interested. Or at least have the community 

establish a means to decide who will have access. 


Aside from the legal and social aspects of site 

selection, there are a number of points 

applicable to most species and places: 

● Carefully observe the conditions where 

your chosen species occurs naturally in 

your are 

● Observe the site and note; also observe 

daily and seasonal changes, particularly 

salinity changes, current/tidal flow, and 

exposure to waves. 

● Ask fishers in the area about normal and unusual factors, storms and floods. 

● Look for sources of domestic and industrial pollution. 

Growing out 

Periodic samples should be taken to observe growth and survival. 

Watch for the occurrence of predators and pests. Do what you can to remove them 

but often it is difficult to control many species. If losses are high, try another area. 

Extension and technology transfer 

Refer to other chapters in this resource book and look for appropriate means to 

involve users in adapting technologies. 

Explore means for experienced aquaculturalists to share experience with others. 

Avoid raising expectations that poor people will get rich quick by culturing high

valued species. Encourage small trials and include local species that can be used 

for family consumption. 

Clams 

There are many clam species found in shallow coastal 

waters. Candidates for aquaculture should be those that 

are naturally found at fairly high densities in mud or sand 

flats. Species found at very low densities can be tried but 

seed supply may be a constraint. 

If exclusive use of small plots can be assured, clams can 

be cultured for family consumption and combined with other species. Such culture 

can reduce the time spent gleaning and provide clams of a larger size. 

Cockles are treated in a separate section and giant clams are not considered here 

because of the difficulty of seed supply. However, some programs are developing 

hatcheries for giant clams.If the seed is available you can probably obtain advice 

on grow-out from the hatchery personnel. 

Sites 

Avoid areas currently used for communal clam collection. Because of water 

circulation patterns, a culture site may have a low natural seed or adult density and

still be good for growing. 

Generally you should look for intertidal areas of sandy mud or sand. Avoid areas that 

are so muddy it is difficult to walk. 

There should be a good tidal exchange as this will bring in the suspended food for 

the clams. 

Pen 

Most clams do not migrate or do so with limited range once they are a centimeter or 

more. (You should observe your local species to see how they behave.) Thus an 

enclosure or pen is not normally required for larger clams. But a pen may be useful 

for small seed, especially after seeding and the animals have not established 

themselves. 

On the other hand, sometimes a pen is useful to keep out other species -- especially 

humans. In some areas fish, like rays, can be serious predators and a pen may help 

in excluding them. 

A pen may be constructed with poles and a low net (up to a meter high). An area 

can also be staked off with a row of bamboo or other sticks. 

Stocking/seed Supply 

Clams spawn seasonally. Observe clam beds for the occurrence of juveniles. 

There might be a conflict with those who collect adult clams if you remove a large 

quantity of clam seeds. Moderate thinning of natural stocks will not have an adverse 

impact on the yields but do the seed collection carefully and try to collect from 

different areas. 

Initially stock at densities no more than two to three times the natural density with 

trials in the range of 200- 600 seed clams per sq m. 

Maintenance 

Feeding is NOT required! In fact there is nothing you can do after you have spread 

the seed clams. Aside from maintaining the pen, if one is used, and keeping the 

area free from debris and obvious predators like snails, there is not much to do. 

Harvesting 

Harvesting can start whenever the clams reach an acceptable size.

One of the reasons for culturing clams is that you can keep them until they reach a 

larger size. Thus, you should harvest the larger ones and return the smaller ones so 

they can continue to grow. The small ones should be left on the surface when the 

tide is rising so they can quickly reestablish themselves in the sediment. 

It is best to harvest an area in a systematic way so you do not dig an area 

frequently. 

Market 

Carefully consider the value of clams in the market according to size. Harvest your 

clams when you think they will give you the best price. 

Economics 

The investment costs for clam culture are small. Even though the market price may 

not be very high, the returns can be reasonable. 

Risks 

The risks involved in clam culture are low as long as you have security of tenure and 

there is not much threat of theft. 

Since there is no feeding or other daily maintenance, the stock can be left in the 

water until you are able to harvest them. However, you will have to determine if 

there is a possibility of seasonal losses due to low salinity. This will depend on the 

tolerance of the species selected. 

Complementarities 

Using an area for clam culture does not preclude its use at high tide for fishing or 

other purposes, as long as this does not adversely affect the bottom or pollute the 

clams. It is not advisable to allow dragging fishing gear over clam beds. 

Other aquaculture, like pen culture of fish, is possible in the same area. The detritus 

from fish culture can enhance the food supply for the clams. 

Special notes 

Like other bivalve mollusks, clams are efficient at removing bacteria and viruses from 

the seawater. It is best that clams be cultured away from residences to avoid 

contamination from domestic sewage. However, if clams are only eaten after being 

cooked well, the threat of contamination from sewage microorganisms is reduced.

Clams are also able to accumulate toxic algae. If you are not aware of the status of 

toxic algal blooms in your area, consult local fisheries or health authorities. 

Cockles 

The main cockle species of interest is the blood cockle, 

Anadara granosa, which is cultured in Malaysia, Thailand 

and a few other places. There may be other species of 

local interest and they can be investigated to determine 

whether the methods suggested here for A. granosa 

would be appropriate. 

Sites 

Blood cockles are mostly found around the mouths of estuaries in muddy areas. The 

adults need a subtidal area but the seed clams can be found on intertidal flats. 

Observe the local occurrence of cockles to assess their salinity tolerance and 

substrate preference. 

Choose a site where the water is in the range of 1-1.5 m at low tide. 

Stocking/Seed supply 

Seed clams can be found in soft-bottom intertidal flats. Usually the mud is too soft for 

walking and a sled or "scooter" with flat bottom is needed to work in the area. 

Observe the mud for the presence of juvenile clams. It may take time to learn how 

to do this. Other fishers in the area may already know how to recognize them and 

what time of year to expect them. 

The seed clams (4-6 mm) are skimmed off the surface of the mud with fine meshed 

scoops. The mesh size should be adjusted to the size of the seed clams. 

The seed clams are then distributed over the growing area from a boat by throwing 

them over with a scoop. Experience will be the best guide to determine stocking 

density. This will depend on water flow and depth. Start with low density and 

increase in subsequent crops. Use a target of 200-300 cockles/sq m at harvest. 

Maintenance

There is little to be done between seeding and harvest. There is no feeding and little 

that can be done about predators. 

Observations are important during the growing period to check growth and survival. 

Gastropod predators should be observed and their distribution determined. You may 

find some areas unfavorable to predators produce higher yields. 

Harvesting 

Cockles are harvested with a "basket rake". This is a rectangular wire basket 

attached to the end of a 2-3 m pole. A rope is attached just above the "basket" and 

tied to the boat. As one person drives the boat around the site in a systematic 

pattern, another pushes the rake down to the mud surface allows it to skim over the 

mud, picking off the clams. The basket is periodically emptied into the boat. 

Market 

Cockles can be taken to market in sacks as long as they are kept damp and cool. 

But hey will not last more than a couple of days. 

Economics 

There is not much equipment required specifically for cockle culture. However, a 

motorized boat is needed. Cockle culture, thus, may be suitable for a fisher who 

owns or has use of such a boat.It would not be wise to invest on a boat specifically 

for cockle culture because the use is rather infrequent. 

Aside from the boat the major investment is labor and time. The profit from cockle 

culture will depend on the local market, supply from fisheries and whether the 

species is in demand. These factors should be assessed at an early stage. 

Risks 

There is not much risk of loss of the cockles if a suitable site has been selected. Before 

a site proves to be acceptable, however, there is a risk of mortality due to predation

or unsuitable water quality. 

Thus, early trials should be small. 

Use of the bottom area does 

not preclude multiple use of the 

overlying water for fishing and 

transport. 

Labor 

Seed collection may involve 

several family members as it is 

not heavy labor. Harvesting is 

more intensive work and may 

not be suitable for all ages. 

Sea cucumbers 

Sea cucumbers (various species of the following genera 

Holothuria, Thelenota, Stichopus, Actinopygya, and Bohadschia) 

are of varying values in local markets depending on local tastes. 

However, they are often exported. Sea cucumbers occur in 

seagrass beds and in sandy/muddy bottoms. If you are in doubt 

about the value of your local species, inquire with fish exporters. 

Not much has been published on sea cucumber culture even 

though a number of attempts to culture them have been made. The methods 

discussed here can be tried for growing sea cucumbers from a small size or for short 

term holding, with some growth, prior to processing for market. 

Sites 

Although sea cucumbers may be found on tidal flats, a shallow-water, subtidal site is 

preferable for culture. Sea cucumbers also occur in sea grass beds but care should 

be taken in using these sites for culture because they are very important for fisheries 

and biodiversity. 

Seed supply 

Collect sea cucumbers from local sources. You will probably find a range of sizes

available. The smaller they are at stocking, the longer it will take to grow to market 

size. For first trials, it would be best to start with larger, submarket-size animals. 

Pen and stocking 

A simple pen made of stakes 

and mesh should be set up. The 

sea cucumbers feed on the 

detritus on the bottom so each 

one will need considerable 

area. The size of the pen will 

depend on conditions. It may 

be better to have a few smaller 

pens rather than one large one, 

just for safety sake. 

Try stocking about 2-3 animals 

per square meter. Monitor the 

growth and survival and 

decrease the density if there 

are signs of stress. 

Maintenance 

There is little to be done between seeding and harvest. There is no feeding. 

Observations are important during the growing period to check growth and survival. 

Harvesting and processing 

Harvesting will be done when you think the size is appropriate. Consult buyers for 

preferred size and base your decision on the risk of loss if marketing is postponed and 

the value of the harvest at a smaller size. Sea cucumbers are marketed in the dried 

form. They must be completely dry to avoid spoilage due to mold. 

Clean the sea cucumbers by cutting open the belly and removing the internal 

organs. 

Immediately scrape the body wall to remove the hard, chalky growth on the 

outside. 

After cleaning boil them in sea water until they become rubbery. Add one teaspoon 

of alum to the pot to inhibit the growth of mold. 

Thoroughly dry the sea cucumbers by smoking or sun-drying until they are .

Pack in plastic bags for market. 

(Source: DENR. 1998. Sustainable Livelihood Options for the Philippines. Booklet 3. Department of Environment and 

Natural Resources, Philippines.) 

Economics 

Lobsters 

The investment in equipment is minimal for sea 

cucumber culture and the seed stock is obtained 

locally. The main investment is time to set up, monitor 

and harvest. A rough estimate of profitability can be 

made once you have decided on the size of pen and 

the stocking density and have determined the local 

market price. 

The product is dried and thus can be stored for 

marketing later . 

There are several species of lobsters and it should be determined 

which are available locally and, of these, whether there are different 

market values. Fishers will be able to provide information about the 

ecology of the local species. This information can help in site 

selection, determining whether juveniles are available, and the size 

that one might expect to achieve. 

Sites 

Lobsters normally require full seawater with little exposure to brackish water. 

They cannot tolerate much reduction in oxygen levels so a moderate flow of 

seawater is needed. For pen culture, seek a site with a sandy or rocky bottom as this 

normally has good water exchange. 

The water depth should be at least one meter at low tide. 

Security will probably be a concern, so the site should be near the residence or such 

that other arrangements (e.g., a guard house) can be made for monitoring.

Culture unit – pens or cages 

Pens 

If funds are available, the farmer may want to invest in a pen. 

A good pen size would be about 5 x 5 m and this can be divided into sections (4 sq 

m for nursery, 6 sq m for transition and 15 sq m for rearing to market size). 

The pens can have bamboo or mangrove poles at the corners and on the sides for 

support. 

Plastic netting used to enclose the pen should cover the ground to prevent the 

lobsters from escape. Farmers may resort to other netting but should watch out for 

the deterioration of material other than plastic. 

The sides can be re-inforced with bamboo slats, coconut slabs or other seawaterresistant 

material to protect the netting. Care must be taken to ensure good water 

exchange and that the whole unit is not subject to destruction by strong waves or 

currents. (Sometimes the more open the cage is the less resistant it is to water flow.) 

Cover the top of the pen with bamboo or nipa for security but allow access for 

feeding and harvesting. 

Cages 

Small, floating or suspended cages offer an 

alternative to pens. Cages can be less expensive 

although the number of lobsters grown may be less. 

This is a good way for a person to start lobster 

culture. They first learn to handle the animals and 

provide feed. Later they can assess whether a 

larger investment of money and time is warranted. 

Cages can be adapted to local conditions and 

materials (bamboo, wood) and the size to a person’s situation. Cages can be 

suspended from a wharf or hung from poles but they should never be left to be 

exposed to air during low tide. Access through the top is needed.

In Vietnam, fishers are culturing lobsters in cages and in pens. The cages are 

of different sizes (2 x 2 x 1 m, 3 x 2 x 1 m and 3 x 3 x 1.5 m). They are 

constructed with iron frames (12-12 mm diameter iron) and covered with 

netting. They sit off the bottom on legs or are suspended 3-4 m below the 

water surface. The pens in Vietnam are about 5 x 5 x 5 m or 6 x 6 x 5 m and 

made of wood and netting. 

The juveniles are stocked for nursery at 6.5-8 mm carapace 

length (CL) and 20-25 mm for culture. At the nursery stage they 

are stocked at the rate of 150-200 animals per cage and in 

cages or pens for growing at five to ten animals per sq m. Food 

consists of small fish, crabs and mollusk that are of low 

economic value. 

The time from stocking to market size is 18-24 months for the ornate rock 

lobster (Panulirus ornatus) and three to four months for the green scalloped 

lobster (P. homarus). 

Stocking/Seed supply 

Juvenile lobsters can be captured by the lobster 

farmer or purchased from other fishers. Care should 

be taken during capture and handling of the juveniles 

to avoid damage. Care should be taken so that 

lobster culture does not pose a threat to the local 

supply of juveniles to the fishery. 

Stock lobsters of the same size in any one unit. They 

are carnivorous and the bigger ones will eat the small ones. 

Feeding 

Feed the lobsters daily, preferably in the morning. Lobsters will eat a variety of foods 

and the farmer should experiment with various fish, mollusks and seaweeds. Remove 

uneaten food before it rots. The food should be cut in small pieces. 

Maintenance 

The pen and cage should be kept clean to maintain water circulation. Remove 

biofouling organisms. Leave them in the cage if the lobsters will eat them. 

Make sure the pen or cage remains intact and there are no escape holes.

As in any aquaculture, the stock should be observed daily to see if there are sick, 

dying or dead animals. They should be removed immediately. 

Remember that lobsters shed their shell when they molt. Do not remove the empty 

shells because they will be eaten by the lobster and provide nutrients. 

Harvesting 

The time to harvest will depend on the stocking size, growth conditions, food and 

preferred size in the market. This may be from six to 24 months. 

Harvest lobsters in the morning by gently scooping them up with a net. 

Lobsters are best taken to market alive. Wrap the lobsters in paper or cloth presoaked 

in seawater and place them in Styrofoam boxes. 

Avoid exposure to fresh water. 

Economics 

The profitability of lobster culture will depend on what material and feed must be 

purchased and what can be obtained directly by the lobster farmer. 

The biggest investment is probably time. 

The labor needed is in the collection of feed and the daily feeding and 

maintenance. This can be done by any family member who is available. 

Risks 

Lobsters may attract thieves. 

They are sensitive to poor water quality (low oxygen or pollutants) and can be killed 

quickly. 

Growing to market size is long, exposing the lobster farmer to the possibility of losses. 

Environmental issues 

Lobsters can be cultured with minimal environmental impact. Feeding rates should 

be adjusted so there is no waste that might pollute surrounding waters. Such 

pollution will also have an immediate and adverse impact on the lobsters. 

Care should be taken to use juveniles wisely. Only enough should be stocked to give

good growth and survival rates. Heavy stocking densities will result in poor growth 

and survival and less returns for the farmer. 

Sea urchin 

Sea urchins have been a traditional food in many countries. With recent 

infrastructure for export of sensitive seafood products like sea urchin eggs, demand 

has risen and over-exploitation of sea urchins is now common. Small-scale pen 

culture of sea urchins exist in the Philippines but they have not been well 

documented. However, the methods are quite simple and local adaptations are 

likely to be needed anyway. 

The first step is to assess the local situation. Are there commercially important sea 

urchins around? Is there a shortage of supply or other reasons to establish culture of 

sea urchins? 

Sites 

Sea urchins are grazers on coral reefs and associated hard or sandy bottoms. They 

are usually found among seaweeds. A similar site, close to home, should be 

identified although it should be kept well away from source of fresh water. 

A site with good water flow is needed as the pen will have unnaturally high 

concentrations of sea urchins and seaweeds. 

Pen or cage 

A pen or cage to hold sea urchins should be constructed. It does not have to be 

very large (up to 2 m x 2 m in area). Poles stuck in the sand with netting would be 

suitable. If a net is a problem, bamboo slats or small mangrove sticks could be used 

for the sides. 

Stocking and seed supply 

There are no guidelines available but common sense in terms of over crowding 

should be used. Small urchins are collected and placed in the pen. It may be best to 

start with sub-market size animals and see how the system works. 

Feeding and maintenance 

Seaweed is collected and added to the pen as needed. Try different species of 

seaweed. Monitor the condition of the pen to see how much is eaten and whether

there is a build up of organic material such as fragments of the sea weed. Clean the 

pen as needed and continue to supply fresh seaweed. 

Check the pen to ensure it is intact. 

Harvesting and market 

Pick out large sea urchins as needed for festivals or for market. 

Check with local buyers to determine how best to market your urchins and when. 

With a stock of urchins you should be in a good position to work with buyers on a 

marketing strategy because you will be able to supply the buyer with the product 

when it is needed. 

Economics 

The profitability of sea urchin culture will depend on what material is used for the 

pen. It is assumed that the seaweed will be collected by a family member. 

The biggest investment is probably time. 

The labor needed is in the collection of feed and the daily feeding and 

maintenance. This can be done by any family member who is available. 

Risks 

Sea urchins are valuable and may attract thieves. 

They are sensitive to poor water quality (low oxygen or pollutants) and can be killed 

quickly. 

The growth from small to market size is long, exposing the farmer to the risk of losses. 

Environmental issues 

Sea urchins can be cultured with minimal environmental impact. Feeding rates 

should be adjusted so there is no waste to pollute surrounding waters. 

Care should be taken to use juveniles wisely. Only enough should be stocked for 

good growth and survival rates. Heavy stocking densities will result in poor growth 

and survival and not result in better returns to the farmer.

Seaweeds 

Seaweeds have both an export market and local use in 

many countries. Seaweed culture for export is an 

important occupation for many communities in southern 

Philippines and eastern Indonesia. It can be undertaken 

on a small-scale but marketing often requires a large 

quantity depending on the proximity of buyers. In this 

chapter we will present a few alternative culture systems 

for consideration. The user will have to determine 

whether there are local markets and what species are 

preferred. 

The common species for culture are Gracilaria spp., 

Eucheuma spp. and in some cases Caulerpa lentillifera. 

Sites 

Seaweeds can be cultured in open water but they are frequently heavily grazed by 

fish. This may not be a constraint if there are large areas of seaweed culture but 

small plots tend to be heavily affected. Gracilaria can be grown in ponds if they are 

available and would be suitable in mudcrab ponds. Eucheuma and Caulerpa can 

not tolerate salinity below approximately 28 ppt so ponds are unlikely to be an 

option except during the dry season when pond salinity will not drop. These species 

may be suitable for small-scale culture inside pens used for other species, except 

rabbitfish, which will definitely eat the seaweed! 

Open water sites should be protected from strong waves and current but have 

good water exchange. The depth should be at least 1m at low water. Sites with firm, 

sandy or rocky bottoms will probably be more desirable. 


Bottom culture in ponds 

Both Gracilaria and Caulerpa can be grown by 

planting small bundles of plant material in the 

bottom mud of a pond. Spacing would be 

about 15 cm for Gracilaria and 1m for Caulerpa. 

For more intensive culture in ponds dedicated to 

seaweed culture the addition of inorganic 

fertilizer would increase yields. 

Lines and floats

Eucheuma and Gracilaria can be 

tied to lines attached to short posts, 

on rafts or on long lines suspended 

from floats. Experiment with 

different line available. 

Various methods have been 

used and much depends on 

the local environment, the 

scale of production anticipated and the materials available. One can use simple 

rafts of a bamboo frame or other materials or lines attached to plastic bottles. 

Tie cuttings or clusters of plant material to the lines at approximately 20 cm intervals. 

Keep the plants and lines clean of other plants and debris. 

Maintain the lines and floats in good condition. 

Harvest 

Harvest the plants after 35-45 days depending on the growth and the weight on the 

lines. 

Clean the harvested plants of foreign material and select the best plants for stocking 

the next crop. 

Processing and market 

If the plants are to be sold dry, spread them on a raised platform or on cement 

pavement on top of a mesh net or dried coconut fronds. 

Turn the plants regularly to promote drying and protect from rain. 

The plants should be washed after drying for two to three days by placing them in a 

basket and shaking in seawater. Spread the plants out again to dry. 

Other market products may be appropriate and if you are not familiar with how to 

prepare the plants consult people who are now harvesting them from wild stocks. 

Advantages/Risks 

Seaweeds are simple to grow but are at risk to grazing by fish. The equipment 

needed is not expensive and may be obtained with little or no cost. On the other 

hand, the market price is not high and commercial markets may require a

considerable quantity to make the effort worthwhile. 

This section was adapted from DENR. 1998. Sustainable Livelihood Options for the Philippines. Booklet 3. Department of 

Environment and Natural Resources, Philippines 

Rabbitfish 

Rabbitfish or siganids (Siganus spp) are desirable fish 

on most markets. They are found in various coastal 

habitats usually associated with reefs and seagrass 

beds. They are herbivorous and unlike groupers are 

suitable for culturing in higher densities because they 

commonly occur in schools. (The technology 

discussed here may be useful for other herbivorous 

species.) 

Sites 

Site selection will depend on the culture method used. Pen culture may be more 

suitable for a larger effort and cover up to a hectare. Such a large pen may be 

suitable for a group or communal effort and would have other benefits in 

management of an area. Rabbitfish can be cultured in cages in a smaller area but 

this will require more frequent inputs of feed. 

The culture site should be in an area where fingerlings are available. It may require 

some trials to assess the suitability of the species available. In the Philippines, S. 

guttatus has been found to be suitable. 

The desired salinity should be determined by the tolerances of the species to be 

grown. Investigate this before selecting a site. 

For pen culture the site should have natural feed available such as seagrasses. Much 

of the area can be shallow or even exposed at low tide as long as there are 

tidepools at least 1m deep within the area. The bottom should be sandy-to-muddy. 

The area should be protected from strong water currents and winds. 

For a cage the site should be deep enough at low tide for the size cage to be used, 

with a buffer of at least 1m below the cage. 


For pen culture enclose the area with a fence made of bamboo strips or other poles 

and nylon nets. The net should be at least 1 m higher than the highest high tide. Use

a fine-mesh net reinforced on the outside with a stronger polyethylene net. 

See the sections in this kit on fish culture for other ideas on pens and for cage 

designs. Note in particular the chapter on seabass. 

Stocking 

Collect fingerlings using a beach seine with fine mesh or whatever is used locally. If 

the fish are 1-2 cm in length (fry stage) they should be held in a cage or pen with 

mesh of appropriate size, approximately 0.5 cm mesh. These are often called a 

happas. Fry can be stocked at 600-1,000 fry/m3. 

For fingerlings in a pen the recommended density is about 50,000 fish per 1 ha. This 

will require some careful monitoring as it depends conditions but mainly on food 

supply. (Large numbers can be "counted" by weighing a counted sample and then 

quickly weighing larger quantities using the number/kg from the sample to 

determine the count.) 

Stocking a cage will depend on the frequency of feeding and water exchange and 

trials are recommended. 

Feeding 

The need to feed will depend on the conditions in the pen and the stocking density. 

Any additional food is likely to be of benefit in increased yield. Additional feed will 

be necessary in a cage. Try different foods available locally including seaweeds, rice 

bran, waste fish (if available.) or other plant material. Commercial fish feed can be 

tried if resources allow. 

Try to monitor fish sizes and numbers and feed approximately 3-5% of the total fish 

body weight per day giving half the amount in the morning and the rest in late 

afternoon. 

Monitoring of growth will indicate whether you are supplying enough food. Also 

monitor for signs of disease or stress. 

Harvest 

Determine the optimal size for the local market and try to harvest at that size. You 

should be able to reach 10-11 fish per kg in three to five months. 

Seine the pen or pull up the cage and scoop out the fish. 

Advantages and risks

Pen culture of rabbit fish requires a large area, which may be possible for a family 

but more likely is best done as a communal effort. This can be a productive venture 

as rabbit fish are primarily herbivorous and the cost of production should be low. 

Pens and cages are subject to damage and losses but careful monitor should 

reduce the losses. 

This section was adapted from Livelihood Options for Coastal Communities Volume 

II, IIRR and SMISLE 1998. 

Prepared by: 

Gary Newkirk


Participants 

A.K.M. Reshad Alam 

Project Manager, GOLDA Project 

CARE Bangladesh Headquarters 

House #65, Road #7A 

Dhanmondi R/A 

Dhaka, Bangladesh 

+880-2-814195 to 98 

+880-2-814183 

carebang@bangla.net 

Warlito C. Antonio 

Aquaculture Technician 

IIRR 

Y.C. James Yen Center 

Silang, Cavite, Philippines 

+63-46-414 2417 

+63-46-414 2420 

information@iirr.org 

S. Ayyappan 

Director 

Central Institute of Fisheries Education 

(CIFE-ICAR) 

Seven Bungalows,Versova 

Mumbai 400061, India 

+91-22-636 3404 

+91-22-636 1573 

ayyapans@yahoo.co.uk 

Ian G. Baird 

Chairperson 

Global Association for People and the Environment (GAPE) 

P.O. Box 860 

Pakse, Lao PDR 

+856-21-251 491 

ianbaird@laonet.net 

Zubaida U. Basiao 

Scientist/Station Head 

Binangonan Freshwater Station 

SEAFDEC Aquaculture Department 

Binangonan, Rizal, Philippines 

+63-2-289 1886; 652 0077 

+63-918-900 1279 

+63-2-289 1886; 652 0077 

zed2@pacific.net.ph 

Arsenia Cagauan 

Associate Professor and Senior Researcher 

Freshwater Aquaculture Center 

Central Luzon State University (CLSU) 

Muñoz, Nueva Ecija 3120, Philippines 

+63-44-456 0680 to 83 

+63-44-456 0681; 44 456 0683 

f-fishgn@mozcom.com 

Barry Clough 

Senior Research Scientist

Australian Institute of Marine Science 

PMB 3, Townsville Old 4810 

Australia 

+ 61-74-753 4444 

+61-74-772 5852 

b.clough@aims.gov.au 

Fernando B. Dalangin 

Municipal Environment and Natural 

Resources Officer 

Sablayan 5104 

Occidental Mindoro, Philippines 

+63-2 535 4557 


Coordinator 

Aquaculture and Aquatic Resources Management 

Asian Institute of Technology 

P.O.Box 4, Khlong Luang 

Pathum Thani 12120 Thailand 

+66-2-524 5212 

+62-2-524 5218 

hdemaine@ait.ac.th 

K. Devadasan 

Director 

Central Institute of Fisheries Technology 

Matsyapuri, Cochin 682029 

Kerala, India 

+91 484 666880 

+91 486 668212 

devadasan@satyam.net.in; dev@cift.ker.nic.in 

Nguyen Huy Dien 

Project Manager (UNDP/FAO Project) 

Ministry of Fisheries 

10 Nguyen Cong Hoan 

Badinh, Hanoi 

Vietnam 

+84 22 855493 

+84 22 855494 

vie98009@undp.org.vn 

Christie Fernando 

Media Coordinator 

Small Fishers Federation 

Pambala, Chilaw 

Sri Lanka 

+94-32-22201 

+94-32-47960 

sff@sri.lanka.net 

Luis Maria B. Garcia 

Scientist II 


5021 Tigbauan, Iloilo, Philippines 

+63-33-335 1009; 336 2965; 336 2937 

+63-33-335 1008 

wgarcia@aqd.seafdec.org.ph 

Wenresti G. Gallardo 

Scientist 


Tigbauan 5021, Iloilo, Philippines 

+63-33-335 1009

+63-33-335 1008 

gallardo@aqd.seafdec.org.ph 


Vice-President for Program 

IIRR 

Y. C. James Yen Center 


+63-46-414 2417 

+63-46-414 2420 

julian@accessway.ph; juliangonsalves@yahoo.com 

John H. Grover 

Senior Aquaculture Scientist 

ICLARM - The World Fish Center 

House 22B, Road No 7, Block H 

Banani, Dhaka 1213, Bangladesh 

+880-2 881 3250 

+880-2 881 1151 

iclarm@dhaka.agni.com 


Fishery Resources Officer (Aquaculture) 

Food and Agriculture Organization of the United Nations (FAO) 

Via Delle Terme di Caracalla 

00100 Rome, Italy 

+39-06-570 55080 

+39-06-570 53020 

matthias.halwart@fao.org 

Nazmul Hassan 

Professor 

Institute of Nutrition and Food Science 

University of Dhaka 

Bangladesh 

+88-2-508 268 

nhassan@bangla.net 

Khorkiat Koolkaew 

Chief of Station 

Songkhla Coastal Aquaculture Station/ Department of Fisheries 

Klongdan, Ranod District 

Songkhla, Thailand 90140 

+66-1-9598444 

+66-2-561 3997 

khorkiatk@fisheries.go.th 

Dilip Kumar 

Team Leader 

Empowerment of Coastal Fishing Communities for Livelihood Security (UNDP/FAO 

Project) 

JALPARI, Kalatali, Cox’s Bazar, Bangladesh 

+88-0341 63871 

+88-0341 63871 

dilipk@agni.com 

Felix Marttin 

Associate Professional Officer 

Food and Agricultural Organization of the United Nations 

Viale Delle Terme Di Caracalle 

00100 Rome, Italy 

+39-06-570 53850 

+39-06-570 53020 

felix.marttin@fao.org

M.C. Nandeesha 

Project Coordinator, GOLDA Project 

CARE Bangladesh 

Road 7/A, House 65 

Dhanmondi 1209, GPO Box 226 

Dhaka 1000, Bangladesh 

+880-2 8114195-8 

+880-2 8114183 

mcnraju@bangla.net 


Program Officer, Agriculture and Natural Resources Management 

Learning Community Program 

IIRR 



+63-46-414 2417; 918-827 5995 

+63-46-414 2420 

Tabrez.Nasar@iirr.org; Tabreznasar@yahoo.com 


Coordinator 

Coastal Resources Research Network 

Dalhousie University 

1321 Edward Street 

Halifax, Nova Scotia B3H 3H1 

Canada 

+1-902-494 2284 

+1-902-494 1216 

Gary.Newkirk@Dal.Ca 

Julia Lynne Overton 

Postdoctoral Researcher 

Centre for Tropical Ecosystems Research 

Department of Ecology and Genetics 

Institute of Biological Sciences 

University of Aarhus, Building 540, Ny Munkegate 

DK8000 Aarhus C 

Denmark 

+45-8942 3349 

+45-8942 3350 

julialynne@compuserve.com 

Elena Z. Par 

Community Organizer/Research Assistant 

International Institute of Rural Reconstruction 

Sablayan, Occidental Mindoro 

+63-917-496 7925 

+63-917-563 9630 

Jurgenne Primavera 

Senior Scientist 


Tigbauan, Iloilo 5021, Philippines 

+63-33-336 2965 

+63-33-335 1008 

jhprima@aqd.seafdec.org.ph 

Mark Prein 

Program Leader/Senior Scientist 

ICLARM – The World Fish Center 

GPO Box 500 

10670 Penang 

Malaysia 

+60-4-6261 606 loc. 401

+60-4-6265 530 

m.prein@cgiar.org 

R.K.U.D. Pushpa Kumara 

Deputy Director/Head Coastal Aquaculture and Sea Farming 

National Aquaculture Development Authority of Sri Lanka 

307 1/1 T.B. Jayah Mawatha 

Colombo 10, Sri Lanka 

+94-1 675316-8 

+94-1-675435 

Tran Van Quynh 

Deputy Directors of Department of Science and Technology 

Ministry of Fisheries 

10 Nguyen Cong Hoan 

Badinh, Hanoi, Vietnam 

+84-4 8354515 

+84-4 7715982 

vie98009@fmail.vnn.vn 

Mokhlesur Rahman 

Monitoring and Evaluation (M&E) Specialist/Consultant 

Fourth Fisheries Project 

Department of Fisheries 

Matshaya, Bhaban 

Romna, Dhaka 1000 

Bangladesh 

+880-2 9554716; 9339516 

+880-2 956 0543 

mrsoft@bdmail.net; m7rahman@yahoo.com 

Alejandro E. Santiago 

36 C. Santos St., Ugong 

Pasig City 

+63-2-671 7927 

+63-2-671 0830 

aldrin@pacific.net 

P.P.G.S.N. Siriwardena 

Head/Inland Aquatic Resources and Aquaculture 

National Aquatic Resources Research and Development Agency 

Colombo 15, Sri Lanka 

+94-1 522005 

+94-1 522932 

sunil@nara.ac.lk 

V. V. Sugunan 

Principal Scientist and Head of Northeastern Research Centre 

Central Inland Fisheries Research Institute 

Barrackpore, Calcutta 743101 (W.B.), India 

+91 361 548757 

+91 361 548757 

sugunan@gw1.dot.net.in 

Wilfredo G. Yap 

Consultant 


17 Times St., West Triangle 

Quezon City, Philippines 

+63-2 372 3980 

+63-2 372 3983 

fredyap@pworld.net.ph 

Yang Yi 

Assistant Professor

AASE/SERD 

Asian Institute of Technology 

G.P.O. Box 4 

Klong Luang, Pathumthank 12120 

Thailand 

+66-2 5245454 

+66-2 5246200 

yangyi@ait.ac.th 

Xiaowei Zhou 

Program Officer 

NACA 

P.O. Box 1040 

Kasetsart Post Office 

Bangkok 10903, Thailand 

+66-2 5611728-9 

+66-2-5611727 

zhoux@fisheries.go.th 

Contributors 

Li Kangmin 

Freshwater Fisheries Research Center 

Qitang, Wuxi City 

Jiangsu Province 214081, China 

+86-510-5556262 

+86-510-5553304 

cosmos@public1.wx.js.cn 

José Aguilar-Manjarrez 

Information Management Specialist 

GILF Division 

FAO of the United Nations 

Viale delle Terme di Caracalla 00100 

Rome, Italy 

3906 570 55452 

Jose.AguilarManjarrez@fao.org 

Miao Weimin 

Deputy Director 

Freshwater Fisheries Research Center 

Qitang, Wuxi City 

Jiangsu Province 214081, China 

+86-510-5558719 

+86-510-5553304 

wmmiao@public1.wx.js.cn


Advisory Committee 


IIRR 


AIR 


IIRR 


FAO-UN 

Dilip Kumar 

NACA 


IIRR 


CRRN, Dalhousie University 

Rolando Platon 

SEAFDEC 

Mark Prein 

ICLARM


Production staff 

Concept Development 


IIRR 


IIRR 

Workshop Coordinators 


IIRR 


IIRR 

Editors 

Carlos William W. Azucena 

Senior Environmental Management Officer 

Bataan Integrated Coastal Management Program – Project Management Office 

(BICMP-PMO) 

Office of the Governor, Bataan Provincial Capitol 

Balanga, Bataan, Philippines 

+63-47-791 6174; 0919-3658563 

+63-47-237 2413 

yamzky@yahoo.com; yamzky@hotmail.com 

Bernadette P. Joven 

#53 Lakeview Subdivision 

Bucal, Calamba 

Laguna, Philippines 

+63-49-244 5265 

bpjoven@yahoo.com 

Siobhan O’Malley 

Information Education Communication Coordinator 

NGOs for Integrated Protected Areas (NIPA) 

Parks and Wildlife, North Avenue 


+63-2-929 6214 

+63-2-929 6214 

siobhann@hotmail.com 

Ma. Stella S. Oliver 

9597 Diamond St. 

Umali Subdivision 

Los Baños, Laguna, Philippines 

+63-49-249 2586; 536 2075 

+63-49-536 2075 

marest@lb.msc.net.ph 

Mayla Hernandez Viray 

29 ADB Subdivision 

Del Remedio, San Pablo City 


+63-49-561 3982; 0919-353 0745 

Mye1025@yahoo.com

Artists 

Carlito N. Bibal 

Philippine Rice Research Institute (PhilRice) 

Maligaya, Muñoz 

Nueva Ecija, Philippines 

+63-44-456 0651 loc. 511 

+63-44-456 0651 loc. 511 

Ric E. Cantada 

Don Gregorio Heights Subdivision 

Bucal, Dasmarinas 

Cavite, Philippines 

+63-46-973 1013; 0919-574 2998 

Rey Cuevas 

334 Carsadang Bago 

Imus, Cavite, Philippines 

+63-0919-425 1113 

artsunltd@hotmail.com 

Jonas Diego 

3349 Apartment 4, Aguila Street 

Rhodas Subdivision, Anos, Los Banos 


+63-49-536 6403 

jonas_diego@yahoo.com; diego_silang@hotmail.com 

Ariel Lucerna 

259 2nd St. 

Salinas, Bacoor, Cavite, Philippines 

+63-0917-439 1962; 463 6619 

ariellucerna@hotmail.com 

Rollie N. Nicart 

09 Sampaloc II, Bucal 

Dasmarinas, Cavite, Philippines 

+63-46-851 1826 

Dekstop Publishing Staff 

Celso Amutan 

Publication Development Associate 

IIRR 

Y. C. James Yen Center, Silang 


+63-46-414 2417 

+63-46-414 2420 

Celso.Amutan@iirr.org 

Hannah K. Castaneda 

4 Castaneda Subdivision 

Mambog, Bacoor 


+63-0917-471 3836; 46-472 0450 

+63-46-973 0647 

email_me@hannahsmail.com 

Ivan Roy Mallari 

#182 Biga 


+63-46-865 0183 

idroid@yahoo.com; ivandroid@mailcity.com 



IIRR


Cavite Philippines 

+63-46-414 2417 

+63-46-414 2420 

Jeff.Oliver@iirr.org 

Administrative Support 

Ma. Aida Gaerlan 

Administrative Assistant 

IIRR 



+63-46-414 2417 

+63-46-414 2420 

magaerlan@yahoo.com 

Logistics Support 

Annex Costa 

IIRR 



+63-46-414 2417 

+63-46-414 2420 

Ronnie De Castro 

IIRR 



+63-46-414 2417 

+63-46-414 2420 

Marlon Manila 

10183 Cordillera St. 

Umali Subdivision 

College, Laguna 

+63-49-536 2428 

Post-production Coordinators/ 

Desktop Publishers 



IIRR 



+63-46-414 2417 

+63-46-414 2420 

jelmontoya@hotmail.com 

Editors 


IIRR 


IIRR 


IIRR 


Head, Publications and Communication Program 

IIRR 

Y. C. James Yen Center


+63-46-414 2417 

+63-46-414 2420 

joy.caminade@pacific.net.ph 

Erlinda Bolido 

#2230 P. Singalong Street 

Malate, Metro Manila 

+63-02-522 1450 

lbolido@hotmail.com 

Illustrator 

Ariel Lucerna 

Cover Design 

Federico Dominguez 

44 Lt. J. Francisco Street, Krus na Ligas 


+63-2-925 0865 

Administrative Support 

Lilibeth T. Sulit 

Administrative Assistant 

Publications and Communication Program 

IIRR, Silang, Cavite, Philippines 

+63-46-414 2417 

+63-46-414 2420 

Lilibeth.Sulit@iirr.org


Correct citation: 

IIRR, IDRC, FAO, NACA and ICLARM. 2001. Utilizing Different Aquatic Resources for 

Livelihoods in Asia: a resource book. International Institute of Rural Reconstruction, 

International Development Research Centre, Food and Agriculture Organization of 

the United Nations, Network of Aquaculture Centers in Asia-Pacific and International 

Center for Living Aquatic Resources Management. 416 p. 

Printed in the Philippines 

ISBN 1-930261-02-0

TABLE OF CONTENTS Acknowledgement Introduction General ...

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