Herreraichthys is an extinct genus of gar from the Late Cretaceous of Mexico.

The genus name honors the famous Mexican scientist Alfonso L.

[1] It is known from Santonian-aged sediments from the "Los Temporales" quarry in Coahuila.

Its occurrence in marine strata suggests that it may have been a fully marine species, similar to what is thought of ancestral gars and in contrast to extant gar, which are found in freshwater habitats.

However, it is also possible that as with the modern alligator gar, it could temporarily survive in the sea.