The blackside dace (Chrosomus cumberlandensis (syn. Phoxinus cumberlandensis)) is a species of ray-finned fish in the family Cyprinidae. It is endemic to the Cumberland River drainage in Kentucky and Tennessee as well as the Powell River drainage in Virginia in the United States. It is a federally listed threatened species. This fish is 50 to 65 millimeters in length. It is olive green in color with black speckling and a black stripe. During the breeding season in April through July the stripe becomes a deeper black, there are red areas on the upper parts, and the fins become yellow.