Minnesota has two catfish species - channel and flathead - and three bullhead species - black, brown, and yellow. These fish are found throughout the state but are most prevalent in warm, fertile rivers and lakes in western and southern Minnesota. The Red, Minnesota, Mississippi, and St. Croix rivers all are known for their excellent catfishing.
To tell a channel catfish from the flathead, look at the lower jaw and the tail. The flathead has a slightly protruding lower jaw, like an under-bite. And its tail is square, where the channel's is forked.
Brown and black bullheads are hard to tell apart. Yellow bullheads can be distinguished by their white barbels (whiskers) under the lower jaw rather than black as on the other two species.
All catfish and bullheads have a sharp spine at the leading edges of the dorsal (top) fin and two pectoral (side) fins. These spines, not the fish's whiskers (called barbels) are what "sting" careless anglers. When the fish is alarmed, it raises and locks its spike fins into an upright position. The pain comes from when a person accidentally pokes himself on the spine, not from any poison released by the fish. Once you learn where the spines are located, catfish and bullheads areas safe to hold as any fish.