The Cyprinodontiformes is an order of ray-finned fish, also called the Microcyprini, and comprising mostly small, fresh-water fish. They are closely related to the Atheriniformes and are occasionally included with them. Many popular aquarium fish, such as killifish and live-bearers, belong here.
- Family Anablepidae (four-eyed fish)
- Family Cyprinodontidae (pupfish)
- Family Fundulidae
- Family Goodeidae
- Family Rivulinidae
- Family Poeciliidae (live-bearers)
- et al.
Death Valley pupfish