Historical accounts tell of Gustave A. "Dolly" Graeber, a catfisherman from Lawrence, Kansas, who fished the Kansas River in the decades around the turn of the century. Early in his fishing career, Graeber caught giant blues by diving underwater with a large snag hook, impaling a fish, and hauling it to the surface. Graeber caught blues to 100 pounds, that rested in crevices under an old mill dam in town.

As he grew older and maybe wiser, Graeber turned to trotlines. In a 1931 interview, he reported that he took his biggest blue, 145 pounds, on a 3-pound carp. Other reports list blues of 150 to 177 pounds from the Kansas River during that era.

In November 1879, the U.S. National Museum received a 150-pound blue catfish caught in the Mississippi River near Saint Louis. Dr. J.B.W. Steedman sent the specimen, which he purchased in the Saint Louis fish market. With it, he sent the following message to Professor Spencer F. Baird, U.S. Commissioner of Fish and Fisheries: "Your letter requesting the shipment to you of a large Mississippi catfish was received this morning. Upon visiting our market this P.M. I luckily found two—one of 144 pounds, the other 150 pounds. The latter I ship to you by express."

Growth studies show, however, that in many populations, 10-year-old blue cats measure only 24 to 32 inches and have just reached maturity. Although growth is faster in some waters, giant blues must be ancient creatures. Yet the oldest blue catfish on record was just 21 years old. (Biologists have rarely sampled large blues.)

Anglers often confuse large dark channel cats with blues. Blue cats typically have heavier bodies and smaller heads, but the best indicator is the anal fin. Blues have 30 to 37 rays on the anal fin, while channels have 24 to 29. The extra rays make the anal fin of the blue cat appear much longer and straighter.

Blue catfish favor large rivers. Their original distribution included the major rivers of the Mississippi, Missouri, and Ohio river basins in the central and southern United States, and the Rio Grande south into Mexico. In the Mississippi, blues range north almost to the Wisconsin border, and introduced populations exist as far east as the Cape Fear River in North Carolina. Introduced populations exist in some California reservoirs.

Blue cats sometimes move upstream in spring, entering smaller rivers to spawn in shallow crevices or to feed in riffles. Like flathead and channel cats, blues spawn when water temperatures reach the low to mid-70°F range. Males prepare a nest in a rock crevice, hollow log, or other cavity where they can protect the sticky clump of eggs the female deposits.

Cats hatch in about five days, reaching three to six inches by their first fall. Fry feed on zooplankton and soon switch to aquatic insects, crustaceans, and small fish. Adult blues eat crayfish, all types of fish, and will eat dead fish as channel cats do.