Xenotoca lyonsi, the Tamazula redtail splitfin, is a bony fish species in the goodeid family.

A 2016 study by Omar Dominguez-Dominguez, et al. split the redtail goodeid into three separate species: X. eiseni, X. doadrioi and X.

[2] The IUCN lists Xenotaca lyonsi as critically endangered.

[1] Xenotoca lyonsi is endemic to the Coahuayana River drainage in Jalisco, Mexico.

[3] Xenotoca lyonsi reaches a standard length of 5 centimetres (2.0 in).