Odd in appearance because of its large, much depressed head and small eyes which are placed high on top of the head and its enlarged pectoral fins, the riffle sculpin (“muddler”) is able to maintain itself among the loose rocks in the gravel of swift riffles. It is a small, scaleless fish which is rather dark and usually mottled in coloration. The average length of this sculpin is between three and seven inches.

The few records indicate that the riffle sculpin is uncommon within the park. First specimen recorded from the park was taken below the dam, above Arch Rock Ranger Station in 1934. Ranger Lon Garrison found one in a small puddle just above the Arch Rock immediately following the 1937 flood in early December. A few others were taken in 1938, near the Incline; in 1938, at Steamboat Bay; and in 1948 from the west boundary of the park.