There are 39 species of catfishes native to the North American continent, and 10 of these inhabit Iowa waters. Family members can be separated by the simplest criteria into three major groups: the large catfishes that include channel catfish, flathead catfish and blue catfish, all of which often reach weights of over 20 pounds; the bullheads, including black, yellow and brown, which rarely exceed 4 pounds in weight; and the madtoms, represented by the tadpole madtom, slender madtom, stone cat and freckled madtom, which are the smallest of the catfishes.
Catfishes are easily distinguished from the other fishes by their smooth scaleless bodies, eight elongated fleshy barbels or "whiskers" abouth their mouth, and the strong, sharp spines that are located at the insertion of the dorsal and pectoral fins. It is beived that the spines are adapted as defensive structures in the catfish family. A locking mechanism allows the fish to extend the spine outward when attacked or touched, making it hazardous for a predator to grasp it and nearly impossible to swallow. Madtoms and small bullheads have glands at the base of the spines that secrete a mild but painful venom when danger is threatened.
The barbels of catfish carry well-developed sensory organs which are used to transmit both touch and taste. Additional taste buds are found at other locations on the body. It has been estimated that an adult bullhead has perhaps 100,000 nerve sensory sites on its body. All of the catfishes are adapted to foraging in muddy and dark waters where feeding by senses is essential.
If there was a family of fishes that was the monarch in any locality, then to Iowa anglers catfishes would be "King". The latest poll on fishing in Iowa revealed that nearly one-third of our fishermen prefer to catch channel catfish and bullheads. Of all the fish caught in the state during 1981, over 6.2 million were channel catfish and nearly 12.5 million were bullheads. Fishermen spent over 4 million days in quest of these fish.
Channel catfish and bullheads are also important commercial food-fish along the Mississippi River, and many commercial fishermen derive at least part of their livelihood from fishing for the catfishes, particularly for channel catfish. Over the last decade approximately 500,000 pounds of channel catfish valued at over a quarter million dollars and 50,000 pounds of bullheads worth about $10,000 were harvested each year from the river. Commercial fishing also occurs along the Missouri River, but the catch is quite small.