prickleback, any of numerous fishes constituting the family Stichaeidae (order Perciformes). All of the approximately 60 species are marine, and most are restricted to the northern Pacific Ocean; a few species occur in the North Atlantic. Members of the family are characteristically elongate, with a low dorsal fin running the length of the body. In most species the pelvic fins are reduced or absent. They get their name from the spiny rays that compose the dorsal fin.