The flathead catfish is a "big-water" species of fish, found quite commonly and widely distributed throughout the Great Border Rivers and in the large interior streams. Few specimens have been reported from the natural lakes, man-made lakes and reservoirs.

The color of the flathead catfish is dark to olive-brown with dark brownish mottlings on the sides, especially in the younger fishes. After inhabiting waters that flow over sand or light bottoms, adults are often light tan or even yellowish in color. The anal fin is very short with only 15 to 17 rays. The head is broad and flat, and the tail is square or very slightly notched. The jaws are heavy, and the lower mandible is longer than the upper.

Spawning occurs in June and July in secluded hides and obscure places. These fish are nest builders, and parent fish guard the eggs and young. The young reach a length of from 2 to 6 inches the first year and are sexually mature in the third or fourth year of life. Adults grow to enormous size. The state record fish, that weighed 81 pounds, was taken from Lake Ellis in Lucas County. Reports of huge flatheads of more than 100 pounds have been passed along through generation along the Mississippi River, but efforts to document their truth have been difficult and may be more river lore than factual.

Flathead catfish are found principally in mud-bottomed areas and prefer deep waters in pools. They feed largely on insect larvae, crayfish, mollusks, fishes, worms, and terrestrial animals that wash into the streams. Small individuals, from 8 to 10 inches in length, have been observed feeding extensively on schools of young minnows in the shallow water. Large flatheads, those more than 20 inches in length, are almost wholly piscivorous in their feeding behavior, either taking fish alive or dead fish from the bottom.

Flathead catfish are exploited by commercial fishermen along the Mississippi and Missouri rivers. Approximately 65,000 pounds of flathead catfish valued at over $32,500 are annually harvested from the Mississippi, and the harvest from the Missouri River averages about 3,300 pounds and is worth about $1,700.

*Mayhew, J. (editor). 1987. Iowa Fish and Fishing. Iowa Department of Natural Resources, Des Moines, Iowa. 323 pp.