Redmouth Pencilfish - Nannostomus nigrotaeniatus : Complete Fish Profile & Care Guide
Table of contents
Introduction
The Redmouth Pencilfish (Nannostomus nigrotaeniatus) is characterized by its generally peaceful demeanour, yet it exhibits fascinating social interactions within its shoaling behaviour. While inherently social, these fish tend to form loose shoals rather than tight schools. Males can be territorial, often engaging in mild skirmishes during daylight to establish and defend their territories.
This species displays a higher degree of aggression compared to other members of its genus, and confinement in small spaces can lead to significant injuries or fatalities. To alleviate such risks, it is crucial to provide a spacious aquarium with strategically placed decorations that create numerous visual barriers. Introducing a group of at least eight, preferably more, Redmouth Pencilfish helps to diffuse aggression, promoting a more balanced social structure. A larger group also enhances their confidence, allowing them to exhibit more of their natural behaviours.
Suitable tankmates for the Redmouth Pencilfish include other peaceful Characids of similar size, smaller species of Catfish, Rasboras, Barbs, and Dwarf Gouramis. They also make excellent dither fish for Apistogrammas and other Dwarf Cichlids, as they primarily occupy the middle and upper layers of the aquarium and are not a threat to fry. However, it is important to avoid very tranquil surface-dwellers like Hatchet Fish and larger, more active species, especially in smaller tanks.
The ideal habitat for Redmouth Pencilfish features a heavily planted aquarium with a dark substrate, supplemented with floating plants, dried leaf litter, and driftwood branches to replicate a natural environment. Moderate water flow is sufficient, making a small air-powered sponge filter an appropriate choice for filtration.
Redmouth Pencilfish are small, with distinctive physical features. They display a silvery beige body colouration, and males have ruby spots on their dorsal, anal, and ventral fins, as well as at the base of the caudal lobes. Females, in contrast, have clear fins. The primary horizontal stripe is broad and located lower on the body, extending over the lower part of the peduncle and ending at the caudal peduncle or slightly onto the caudal fin. The secondary horizontal stripe is less pronounced and lower, extending to the end of the peduncle. These fish also feature a red marking on their faces.
Redmouth Pencilfish Photos
Sexual Dimorphism
Identifying the gender of Redmouth Pencilfish can be moderately challenging, as there is noticeable variability in patterning among individuals from various geographic locations. Generally, males tend to have a somewhat slimmer body shape and exhibit more vivid colouration compared to females. However, these characteristics may not be uniformly present across all individuals. Consequently, precise and attentive observation of these subtle visual differences is crucial for accurate sex determination within this species.
Quick Facts
| Scientific Name | Nannostomus nigrotaeniatus |
|---|---|
| Year Described | 2013 |
| Kingdom | Animalia |
| Classification | Actinopterygii |
| Order | Characiformes |
| Family | Lebiasinidae |
| Genus | Nannostomus |
| Origins | Venezuela |
| Max Size | 4 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle |
| Difficulty | Beginner - Intermediate |
| Shoaling | Yes |
| Best kept as | Groups 8+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg-Scatterer |
| Average Lifespan | Up to 5 Years |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 5.5 - 7.0 |
| GH | 2 - 10 |
| TDS | 18 - 215 |
| ℉ | 75 - 82 |
|---|---|
| ℃ | 23 - 27 |
Natural Habitat
Regrettably, comprehensive details pertaining to the natural habitat of the Redmouth Pencilfish remain scarce. Nonetheless, it is established that this species is indigenous to the clear waters of the Rio Ventuari, a tributary of the Orinoco River located in southern Venezuela, South America.
Breeding
Culturing Redmouth Pencilfish can be relatively uncomplicated, though it requires using a dedicated breeding aquarium to optimize offspring survival. Creating an ideal breeding environment involves utilizing dim lighting and introducing clusters of fine-leaved plants, like Java Moss, or alternatives such as spawning mops, plastic grass-like matting, a layer of glass marbles, or mesh. These materials provide suitable surfaces for the eggs to attach to during spawning.
For enhanced breeding efficacy, it is recommended to maintain slightly acidic to neutral water pH levels and a slightly elevated temperature compared to that of the community aquarium. Implementing an air-powered sponge filter or an air stone is beneficial for maintaining appropriate water circulation and oxygenation. Group spawning requires roughly an equal number of males and females, with conditioning through a diet rich in live and frozen foods prior to spawning. This approach facilitates successful breeding with minimal issues.
Pair spawning is another effective method. In this approach, males and females are conditioned separately in different tanks with a high-quality diet. When the females show signs of being egg-laden and the males display peak colouration, select the healthiest female and most vibrant male for introduction into the breeding tank. Spawning is expected the following morning.
About 2 to 3 days post-spawning, it is advisable to remove the adult fish to allow the eggs and fry to develop without disturbance. The first indications of fry should become noticeable approximately three days after the adults are removed. Initially, feeding the fry with Paramecium or suitably sized dry food is recommended.
As the fry grows, transitioning them to appropriate food sources like microworms or baby brine shrimp is crucial. Following these breeding guidelines and providing proper care allows aquarists to experience the gratification of successfully breeding Redmouth Pencilfish and observing the development of their vibrant offspring.
Diet & Feeding
In their natural environment, Redmouth Pencilfish adopts a micro-predatory feeding behaviour, primarily subsisting on minute invertebrates and zooplankton. However, in the aquarium setting, they demonstrate dietary adaptability and can be readily acclimated to high-quality, appropriately sized dried foods.
To fully satisfy their nutritional needs, it is essential to enhance their diet with regular offerings of small live and frozen foods. Bloodworms, white mosquito larvae, daphnia, and baby brine shrimp constitute ideal supplemental food choices. These additions not only promote the overall well-being of these intriguing Pencilfish but also contribute to a well-rounded and balanced diet in the aquarium environment.
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