Xenotoca doadrioi or San Marcos 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.

[3] It lives in ponds, springs and reservoirs, as well as seasonal streams connected to them.

[3] In the wild, it primarily eats algae, aufwuchs, crustaceans and insect larvae.

[4] Besides coloration, X. doadrioi differs from X. eiseni and X. lyonsi in features such as the number of rays in certain fins and some scale counts.