Knobfin Sculpin

Distinguished from all other congeners, except Cottus hypselurus and Cottus caeruleomentum, by the blue chin and belly on spawning males. Differs from Cottus hypselurus by dorsal fin spines 8-9 (versus 6-7); pectoral fin rays 16-17 (versus 13-15); pigmentation of the ventral surface of the peritoneum weak (versus moderate to strong ); dorsal-fin union moderate to wide versus slight to moderate. Can be differentiated from Cottus caeruleomentum by caudal base band notched (versus non-notched); dorsal fins moderately to widely connected (versus slightly connected); pectoral fin rays 16-17 (versus 12-15); ventral surface of peritoneum weakly pigmented (versus moderately to strongly pigmented) (Ref. 83416).

Dorsal spines (total): 7 - 9; Dorsal soft rays (total): 15 - 19; Analsoft rays: 12 - 14

Found in cool to cold spring-fed creeks and rivers with cobble bottoms (Ref. 83416).

The knobfin sculpin (Cottus immaculatus) is a species of fish in the family Cottidae. It is found in the United States, inhabiting the Current, Eleven Point, Spring and White river systems in the Ozark Highlands of Arkansas and Missouri. An invasive non-native introduced population is present in the Pomperaug River drainage in Connecticut. It reaches a maximum length of 9.0 cm. It prefers rocky riffles of headwaters and creeks.