The boulder darter (Etheostoma wapiti) is a species of ray-finned fish in the perch family. It is endemic to Alabama and Tennessee in the United States, where it occurs in the Elk River system and Shoal Creek. It is found in small rivers and fast-flowing streams, at least 2 ft (0.6 m) deep, with boulders or a rocky base. It feeds on aquatic insect larvae but little is known of its natural history. The population trend of this fish is unknown but it is affected by a rise in siltation and the impoundment of water within its range by the building of dams. The International Union for Conservation of Nature has assessed its conservation status as being "vulnerable".