The Gila topminnow (Poeciliopsis occidentalis), is a small fish usually about two inches in length. It is found in Arizona, New Mexico, and in parts of Southern Mexico. The Gila topminnow prefers shallow, quiet waters with dense algae and plant material. At one time considered to be the most common fish in the Gila River Basin and most abundant. However due to non-native fish competition, fish, 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 topminnow exhibit dimorphism, where males look differently 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’s 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 topminnow can survive for up to two days by burrowing in the mud.
At the Phoenix Zoo
Phoenix Zoo maintains a breeding population of Gila topminnow at the Conservation Center. In an effort to increase wild populations we work our partners at Arizona Game and Fish to identify areas in the wild where topminnow that are born here can be released. Through its ongoing participation in Gila Topminnow conservation, the Phoenix Zoo hopes to preserve this fascinating native species in its historic range for generations.