Gila Topminnow (Poeciliopsis occidentalis)

DESCRIPTION: L=2.25" (57mm) in females and males are smaller. Males are recognized by very long gonopodium which is a modified anal fin used as a sexual organ for internal fertilization. Breeding males are also black and thin versus the silvery-tan color of the more robust females. Both sexes have upturned mouths.
NATURAL HISTORY: Omnivorous. Occurs in warm, shallow, slow-flowing creeks and small to medium sized rivers. This is the only fish species in Arizona to give birth to live young (versus eggs). The females give birth to 1-15 young per brood, but the females often have a second brood already developing while the first brood is being born. Endangered mostly due to predation and competition from the introduced Mosquitofish.