Gila Topminnow (Poeciliopsis occidentalis occidentalis) is a small (up to 6 cm) fish that was historically abundant and widespread in the Gila River system and Rio Yaqui drainages of New Mexico, Arizona, and Sonora, Mexico. Though still abundant in Sonora, they were extirpated from New Mexico and then reintroduced near Lordsburg, and in Arizona they have been restricted to fewer than 20 isolated populations. They are typically found in lowland vegetated streams that are warm and shallow with low to moderate flow. Females are fertilized internally and bear live young.