Faunaland petshop, Breda, May 2 2015. The aquarium only mentioned it being the smallest Live-bearing fish-species.
Yes, that name is used, particularly in the USA; but it's not a killifish, it's a livebearer related to the guppy etc. In the UK it is usually called the mosquito fish, but that can be confused with the Gambusia livebearers which are used for mosquito control in some places. Safer to stick to Heterandria formosa. Easy to keep as they don't need high temperatures or large tanks. Alan