; subclass Actinopterygii, order Cypriniformes)
A small family of freshwater fish that have a compressed body, rather straight dorsal profile, and a strongly curved belly, terminating in a narrow tail (hence ‘hatchetfish’). The large pectoral fins are operated by relatively huge shoulder muscles and can move so fast that the fish actually leaves the water and flies over the surface, as a real flying fish. Hobbyists keeping Gasteropelecus sternicla (keeled belly), 5 cm, in an aquarium should keep a lid on the tank! There are about nine species, found in S. America.
Subjects: Zoology and Animal Sciences.