Cyprinodontiformes

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