Deepwater Sculpin

The deepwater sculpin is a small fish on average between 51–76 millimetres (2.0–3.0 in) in total length. Its body is generally flattened in shape and tapers from the head to the caudal peduncle. It does not have true scales but some spines are present on the opercle, body, and fins. The skin is mottled green, gray and brown on the back and whitish underneath. The deepwater sculpin can be distinguished from other freshwater sculpins in its range by a distinct gap between the two dorsal fins. It is most similar in appearance to the fourhorn sculpin, a fish found in salt and brackish water in the arctic but lacks the four bony spines found on the head of that species. Age estimation with otoliths suggests that deepwater sculpin can live up to nine years.

The deepwater sculpin is found from the Gatineau through the Laurentian Great Lakes, Manitoba, and Saskatchewan to the Great Slave and Great Bear Lakes. It is also found in Waterton Lake within Waterton Lakes National Park and Glacier National Park. Within its range, it is limited to deep, well-oxygenated lakes with ties to former Wisconsinan glacial lakes or the Champlain Sea. The deepwater sculpin inhabits the demersal zone. It prefers water temperatures that remain less than 5 °C (41 °F). In lakes in the southern part of its range, it has been observed only in deep water where temperature remains cold annually.

The deepwater sculpin feeds primarily on small crustaceans Mysis diluviana and Diporeia. They will also take chironomid larvae. Zooplankton are likely prey at the larval stage.