Mexican darter
The Mexican darter (Etheostoma pottsii), also known as  the Chihuahua darter or Mexican darter, is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to Mexico where it is the only species of darter to naturally occur in the Pacific drainage. This species can reach a length of  TL. References

Etheostoma
Freshwater fish of Mexico
Fish described in 1859
Taxonomy articles created by Polbot