Slimy Sculpin

The slimy sculpin, Cottus cognatus, is a freshwater species of fish that inhabits cool, rocky streams, rivers and lakes throughout northern North America and eastern Siberia. The slimy sculpin is found in freshwater and sometimes brackish water in areas with rocky or gravel type bottoms. The slimy sculpin is a nocturnal fish that usually spends most of its time on the stream bottom and seeks shelter under rocks and logs, especially during spawning season. When it swims, it sometimes appears to be “hopping” along the bottom because of its inefficient ability to swim. This is partly due to the absence of a swim bladder, which normally gives buoyancy to a fish.

The slimy sculpin is an ambush predator. It feeds primarily on insects, but also eats crustaceans, fish eggs, and small fish.

The slimy sculpins’ size and poor swimming ability makes it a great prey item for larger fish. Because of this, fly patterns that resemble or imitate sculpins have been created for fly fishing for trout and other fish.

Researchers are also interested in this fish species. The slimy sculpin has been studied in waters where there is current acidification (water that is more acidic). The sculpin were found to be less active and have lower rates of reproduction when found in these waters. For these reasons, the slimy sculpin has been identified as a good indicator species (a species that indicates a change in environment by a difference in behavior or population size) for acidification in lakes and ponds and possibly for streams.