The stonecat is a widely distributed and relatively common member of the madtoms. It is the largest madtom in body size, is the species with the longest life span, and has a lower relative fecundity than other madtoms. It may be used for bait, especially in bass fishing.


Stonecats are olive, yellowish, or slate colored on the upper half of their bodies and are the only madtoms that exceed 7 inches in total length. The stonecat has backward extensions from the sides of the toothpatch on the roof of its mouth. In most cases, the stonecat has a patch on its nape, a white spot at the rear of the dorsal fin base, and another white spot on the upper edge of the caudal fin. There are either no or a few weak teeth on the rear of the pectoral spine.


Of 261 specimens collected from Missouri and Illinois streams, the largest specimens were a 7-inch male and a 6.4-inch female. Growth is fastest in the first year of life. Individuals up to 5.3 inches are at least 3 years of age. Individuals greater than 6.5 inches are 4 years and older. The largest and oldest stonecat ever collected was 12.25 inches in total length and 9 years old.

Spawning behavior

Females mature at 3 to 4 years of age and a mean standard length of 4.7 inches. Clutches are guarded by males under large flat rocks in pools or crests of riffles. Rocks used as spawning cover averaged 200 square inches and were found in water averaging 34 inches deep.


Mayfly larvae are important food for all sizes of stonecat. Excluding those specimens greater than 4.7 inches in standard length, all stonecats consume stonefly, caddisfly, and midge larvae.

Stonecats less than 3.1 inches in standard length consume blackfly larvae, whereas larger stonecats consume more crayfish. Like most typical madtoms, stonecats consume a variety of organisms that are only infrequent prey, including fish eggs, worms, amphipods, and chilopods.


The stonecat has a widespread distribution. It exists in the Great Lakes, the St. Lawrence River, drainages of Hudson Bay, and the Mississippi River basin. It can be found from the Hudson River drainage of New York, west to the Red River drainage of Hudson Bay. It is found in drainages of the Mississippi River basin from Quebec to Alberta, southerly to northern Alabama and Mississippi, and westerly to northeastern Oklahoma.


Generally, the stonecat inhabits riffles of medium to large rivers in places with many large rocks. It also occurs in lakes where currents or wave action produces streamlike conditions. In the main channels of large rivers, it has been found in swift water over sand substrate.