Slimy sculpin

Cottus cognatus

Species Type: fish

Conservation Status: endangered

IDENTIFICATION

The slimy sculpin has a long, fairly slender body and reaches a length of approximately 4 ½ inches. The body is wider at the front and tapers to a slender tail. It is dark brown, green, or gray above. There are often two dark saddles under the second dorsal fin and large black spots at the front and rear of the first dorsal fin (often joined into a black band).

The dorsal fins are long and low, with the second dorsal fin being about twice the length of the first. The dorsal fins are separate from each other to their bases. The anal fin is directly below and approximately the same length as the second dorsal fin.

The breeding male is dark gray to black overall with an orange edge on the first dorsal fin.

Sculpins are among the most difficult freshwater fishes to identify! Most are drab and variably mottled, so color patterns are not of great use in identifying them.

Distribution & Habitat

The slimy sculpin occurs throughout Alaska and most of Canada. Within the U.S. lower 48, it can be found in three general areas: northern Idaho, Washington, and Montana; the Great Lakes & southern Wisconsin and northern Iowa; and in the northeastern U.S. along the Appalachians from northern Virginia in the south to Maine in the north. They are also known to occur in eastern Siberia.

Within New Jersey, slimy sculpins can be found in the northwestern portion of the state, primarily within the Highlands region, with the Watchung Mountains at the southeastern extent of the range.

They prefer rocky riffles of cold streams and rocky areas of lakes.

Diet

Slimy sculpins are invertivores, consuming immature aquatic insects and crustaceans along the bottom. They may also consume other invertebrates as well as fish eggs.

Life Cycle

Slimy sculpins spawn in New Jersey between April and May. The eggs are laid under a rock or submerged tree root. Eggs are guarded by the male and hatch in about a month. They reach sexual maturity at 2-3 years of age.

Current Threats, Status, and Conservation

This species is sensitive to warming water. Increased stream temperatures caused by climate change have negatively impacted this species and may continue to do so. Additional threats to this species include habitat loss and pollution. Its population has declined in New Jersey and it has disappeared from portions of its range in the state.

In 2016, the New Jersey Endangered and Nongame Advisory Committee recommended a Threatened status for this species. In January 2025, the rule proposal for upgrading the species status was finally adopted.

References

Arndt, Rudolf G. 2004. “Annotated Checklist and Distribution of New Jersey Freshwater Fishes, With Comments on Abundance.” The Bulletin: New Jersey Academy of Science. Vol. 49, No. 1.
Page, Lawrence M. and B.M. Burr. 2011. Peterson Field Guide to Freshwater Fishes of North America North of Mexico.

Text written by Michael J. Davenport in 2016.

Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Scorpaeniformes
Family: Cottidae
Genus: Cottus
Species: C. cognatus