The biggest threat to a wild population is non-native fish species.
Zoogoneticus tequila, Tequila splitfin or simply Tequila fish, is a species of goodeid fish (family Goodeidae) from Mexico. The specific epithet, tequila, derives from the Tequila Volcano, which looms near the type locality. Zoogoneticus tequila is endemic to the Ameca River basin in west-central Mexico. Its current distribution is restricted to a single spring pool in Teuchitlán, only 4 metres (13 ft) in diameter, where a population consisting of less than 50 adult fish live. Even in this habitat, it is outnumbered by introduced guppies by a factor of six. Before the discovery of the pool population in 2000/2001, Zoogoneticus tequila was generally thought to inhabit rivers; however, no fish could be found in the original habitat and the species was considered extinct in the wild. Introduced fish species have been implicated in the disappearance of Zoogoneticus tequila from its type locality. Habitat deterioration may also have contributed. Pollution and water extraction are threats to the pool where the wild population persists. Captive populations are maintained by aquarists.
Along with other Mexican goodeids, Zoogoneticus tequila are viviparous; this led the genus to be originally included in family Poeciliidae. Clutch size is up to 29 young. Males are smaller than females, with standard length up to 4.1 cm (1.6 in) in males and up to 5.8 cm (2.3 in) in females. Total length can reach 7 cm (2.8 in) in females. The sexes can also be distinguished by colouration.