Xenotoca

Xenotoca is a genus of fish in the family Goodeidae from Mexico, where found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma–Grande de Santiago, Panuco, Cuitzeo and other basins of the Mesa Central. While no goodeid is a very common aquarium fish, the redtail splitfin (X. eiseni), is one of the most common aquarium goodeids. Its relatively bright colors offset its reputation for being aggressive towards tankmates, occasionally even killing them. Similarly to that species, two species described in 2016 have males with red-orange tails, but this feature is not shared by the remaining members of the genus. The Xenotoca species are small, reaching up to 9 cm (4 in) in standard length.