Astyanax baileyi is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American characins. This fish is found in northern Guatemala. Based on several visual aspects, it was once considered a member of the genus Bramocharax, which is now obsolete, and has since been synonymized with Astyanax. As such, former members of Bramocharax are now a part of Astyanax, like Astyanax bransfordii and Astyanax caballeroi.

The scales of its body are largely silver, with a yellow or yellow-green cast. Its fins are some mix of orange and pink, and there is a dark patch on its tail-fin joint that spreads onto the tail fin itself. These are not unusual features for a member of Astyanax, but other aspects are somewhat unorthodox, hence why it was once considered a member of a different genus. In modern ichthyology, the unusual parts of A. baileyi's appearance - like a compressed body and a long snout - are considered to be adaptations to its environment and role in the food web.

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