The grotto sculpin (Cottus specus) is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins.

[2] It is found in the United States where it only inhabits the Bois Brule drainage (although not recorded from the main stream itself) in Perry County of southeastern Missouri.

[2] This cavefish lives in underground streams and their resurgences.

[2] It was formerly confused with the more widespread C. carolinae, but can be separated by (among others) its smaller eyes and various degrees of reduced pigmentation.

[2][3] It is one of only three known cases of troglomorphism in the sculpin family, the others also involving U.S. Cottus (C. bairdi—cognatus species complex in Pennsylvania, and C. carolinae in West Virginia).