Tequila Splitfin Zoogoneticus tequila

The Tequila Splitfin is a goodeid native to the Ameca River basin below the Tequila Volcano in western central Mexico but it is now limited in the wild to one spring pool. Introduction of invasive species is a key cause of its decline and it is at high risk of total extinction except for captive populations by aquaria.

The male, above left, is dark charcoal with a bright yellow or orange band on the tail. The anal fin is split, leading to the name "splitfin" for these goodeids. The female, above centre, is paler and without the yellow band. She gives birth to live young rather than eggs. Both have a dark spot before the tail. The larger females grow to 6-7cm.