Der Zwergkärpfling

Dwarf killifish (Heterandria formosa) are among the most fascinating aquarium inhabitants, despite their rather plain coloration and small size. Their reproductive biology is particularly interesting. The males, measuring only 2 cm, defend small territories and impress each other with their fins stretched to the point of breaking. They mate with the females, which are about one third larger, using a special, highly mobile mating organ known as the gonopodium. This is followed by an extraordinary gestation period during which the females provide nutrients to their differently developed embryos. After a gestation period of several weeks, they give birth to only a few fully independent fry. A few siblings follow every few days. Michael Kempkes describes the dwarf killifish in all its facets in his monograph. They are charming creatures.