Tequila Splitfin

Along with other Mexican goodeids, Zoogoneticus tequila are viviparous; this led the genus to be originally included in family Poeciliidae. The 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. The clutch size is up to 29 young. Total length can reach 7 cm (2.8 in) in females. The sexes can also be distinguished by colouration. Adult males have cream-colored terminal bands on the anal and dorsal fin. The caudal fin of adult males has crescent-shaped band of red-orange, orange, or yellow. This crescent-shaped tail is one of the distinguishing features that helps to separate this fish from the other species within its genus: Zoogoneticus quitzeoensis. The rest of the caudal fin is not pigmented and is transparent. Some large adult females share this caudal coloration but generally their caudal fins are transparent. Both sexes display olive shaded, mottled bodies with males typically darker than the females. Generally, adults will lose the mottled coloration in their caudal peduncle as they age. Juveniles are lighter colored with more obvious mottling.

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 found in the early 2000s. Before the discovery of the pool population in 2000/2001, Z. 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 Z. tequila from its type locality. The small pool where the endemic population of Z. tequila currently inhabits is made of mostly mud and silt, along with rocks, sand, and minimal vegetation. The fish are primarily found in more shallow depths within the pool, preferring warmer temperatures. After reintroduction efforts for seven years, the Z. tequila population has recovered and now flourishes in its endemic location. The Ameca River Basin is home to many endemic species that fall within the Goodeidae family, but like Z. tequila, most remain outnumbered by introduced species such as the guppy. With such a small population of minimal juveniles and a few adults, Z. …

The female Z. tequila fish have a single, median ovary that is common amongst the entire Goodeidae family. During reproduction, the embryos develop in the cavity of this ovary. Females give birth to free-swimming fry after the development within the ovary cavity. During each brood, females will produce 10-29 offspring, typically during the summer season, though some studies have found females to reproduce in winter in rare occurrences. Once the fry are given birth to, they are left to fend for themselves, with no parental care provided by the mother. Sexual maturity for this species is reached around 6-10 weeks of age, when the life cycle of this fish starts over again.