just found this
Killifish belong to the order Cyprinodontiformes. The word "Killifish" is Dutch for "fish of the creek", but killies are found in many environments worldwide (except Australia, China, and Northern Europe), ranging from mud holes to lakes, from swamps to rivers, from hot springs to estuaries, from desert pools to rain forest brooks.
Killies are popular aquarium fish for many reasons. They are generally hardy, small fish that require little space and very little equipment to maintain them. The colors of some killies rival those of the flashiest reef fish. Killifish consume copious quantities of insects in their diet, moquito larvae being a favorite food to the point where they have been tried as a form of biological mosquito control. Killies exhibit interesting spawning behaviors, and their eggs are unusually tough and resistant to temperature changes and dessication, so they are commonly traded through the mail. While all prefer live foods, most are undemanding eaters.