How to know it
Two fish, easily told apart. A channel catfish is slim and grey to blue, with a deeply forked tail, a rounded anal fin and, on a younger fish, scattered black spots. A flathead is the one that looks like it was dropped on its head: a broad flat skull, a squared tail, a mottled brown and yellow body, and a lower jaw that juts past the upper. Both have barbels — the whiskers — and sharp spines in the pectoral and dorsal fins that a hand has to avoid. Bullheads, the small cousins in ponds and backwaters, have square tails and never get big.
Where it lives
Big rivers and their backwaters: the Mississippi, the Minnesota, the St. Croix, the Wisconsin, the Red River of the North, the lower Wolf and Fox. Channel cats also live in reservoirs, flowages and some lakes, and in rivers they gather below dams, in the deep outside bends and along the riprap. Flatheads want deep water with wood: logjams, undercut banks, the scour holes below wing dams, where they hold by day and move out at night to hunt. The Red River is known for the size of its channel cats, and the lower Minnesota and the Mississippi pools for flatheads.
Through the year
Catfish spawn in early summer when the water warms past 70, in cavities under banks and logs. The fishing comes on in late spring as the water warms, peaks through the summer — the hot, still nights of July and August are flathead time — and tapers in fall as the fish move to the deep wintering holes, where they are sluggish until spring. Channel cats feed in the daytime too, especially in current and stained water; flatheads are almost wholly a night fish.
How guides fish for it
From an anchored boat, with the rods in holders. For channel cats: cut bait, chicken liver, stink bait or crawlers on a circle hook, fished on the bottom below a dam or on a current seam, and the rods bend one after another. For flatheads: a live bluegill, sucker or bullhead on a heavy rod and a big circle hook, set near a logjam after dark and waited on, sometimes for hours, for a fish that pulls like a truck. A catfish guide knows the river at night — the snags, the current, the holes — and runs a boat set up for it, with lights, rod holders and a big net. Many trips start at dusk and run past midnight.
Handling and release
Mind the spines on a small fish; a big one is held by the lower jaw or with a hand under the belly. Channel cats are kept and eaten widely. Flatheads over a certain size are released by most guides and by rule on some rivers, because a thirty-pound flathead is decades old.
Rules
Bag limits and length limits vary by state and by river, and some rivers have flathead-specific rules. The Minnesota DNR and the Wisconsin DNR publish them, and a guide will know the ones for the water you are on.
