The Bear Lake sculpin, Cottus extensus, is a small fish that naturally occurs in only one place in the world, Bear Lake, on the Utah - Idaho border. The Bear Lake sculpin has, however, been introduced and become established in Flaming Gorge Reservoir, on the Utah - Wyoming border. The Bear Lake sculpin is listed as a sensitive species by the Utah Division of Wildlife Resources.
Like other sculpin species, the Bear Lake sculpin is benthic, spending much of its time on the bottom of the lake. The species eats invertebrate animals and, in turn, is an important food source for cutthroat trout and the introduced lake trout. The Bear Lake sculpin spawns from April to May among rocks close to the shoreline.