The Gila topminnow (Poeciliopsis occidentalis), is a small fish approximately two inches in length. It is found in Arizona, New Mexico and parts of Southern Mexico. The Gila topminnow prefers shallow, quiet waters with dense algae and plant material. At one time this fish was considered to be the most common and abundant fish in the Gila River Basin; however, due to non-native fish competition, water draws and habitat destruction, Gila topminnow numbers dwindled until it was listed as endangered in 1967. Currently, there are 14 known naturally occurring localities in Arizona for this species.

Gila topminnows exhibit dimorphism, where males look different than females. In general, females are larger than males. Their color ranges from a tan to olive body with a white belly; however, during breeding season, mature, dominant male fins turn yellow and their bodies darken to nearly black. They are extremely hardy and survive in waters at temperatures near freezing and up to 100 degrees. During times of complete water evaporation, Gila topminnows can survive for up to two days by burrowing in the mud.

At the Phoenix Zoo

The Zoo maintains a breeding population of Gila topminnow at The Arthur L. and Elaine V. Johnson Conservation Center. In an effort to increase wild populations, we work in conjunction with the Arizona Game and Fish Department to identify areas in the wild where Gila topminnows that are born at the Zoo can be released. Through its ongoing participation in Gila topminnow conservation, the Zoo hopes to preserve this fascinating native species in its historic range for generations.