cool-critters:

Mexican tetra (Astyanax mexicanus)

The Mexican tetra or blind cave fish is a freshwater fish of the family Characidae of the order Characiformes. The type species of its genus, it is native to the Nearctic ecozone, originating in the lower Rio Grande and the Neueces and Pecos Rivers in Texas, as well as the central and eastern parts of Mexico. Growing to a maximum overall length of 12 cm, the Mexican
tetra is of typical characin shape, with unremarkable, drab coloration. Its blind cave form, however, is notable for having no eyes or pigment; it has a pinkish-white color to its body (resembling an albino). A. mexicanus is a peaceful species that spends most of its time
in midlevel water above the rocky and sandy bottoms of pools and
backwaters of creeks and rivers of its native environment.

photo credits: Grand-Duc

The cave form is occasionally available for aquariums, and overall is a good fish for quiet aquariums.The only downside is they tend to nip anything that gets near their face, in case it’s food, so they shouldn’t be housed with particularly delicate fish that can’t take an occasional light nip.