Several of these natives have behavior patterns that may be unfamiliar to the tropical-fish fancier. All freshwater sculpins have a similar size and shape. They are typically less than six inches in total length, and have large, flattened heads and very large mouths with fleshy lips. The pectoral fins are greatly expanded and, in general, the sculpins resemble the marine sculpins, scorpionfishes, and sea robins, to whom they are related. All of the freshwater sculpins are cryptically colored and, as its name implies, the mottled sculpin has blotches of tan, brown, yellow, and black covering its body.
Mottled sculpins have a wide but discontinuous distribution.
They range from northern Georgia and Alabama to Canada in eastern North America, and throughout the northern Rockies to the west. They are not found in the central parts of North America. Sculpins are most abundant in clear, rapidly flowing freshwater streams, and are usually found in association with trout, dace, and other fish requiring clean water and low temperatures. Sculpins are bottom-dwellers, and seldom swim more than a few centimeters above the substrate. They are most commonly found resting beneath flat rocks.