The channel catfish (Ictalurus punctatus), known informally as the "channel cat", is a species of catfish native to North America. They are North America's most abundant catfish species, and the official state fish of Kansas, Missouri, Nebraska and Tennessee. The channel catfish is the most fished species of catfish in the United States, with around 8 million anglers angling them per year. The popularity of channel catfish for food has contributed to the rapid expansion of this species' aquaculture in the United States. It has also been widely introduced to Europe, Asia and South America, and many countries consider it an invasive species.

The channel catfish appears to be a rather old species that has persisted for nearly 20 million years, as fossil remains assigned to it are abundant in numerous geological formations of central North America from the Miocene onwards. Fossil remains of the channel catfish are known from the Sheep Creek, Runningwater, Valentine, Ogallala, Ash Hollow and Seymour Formations of the United States. The oldest of these remains are known from the Middle Miocene of South Dakota. These remains were initially assigned to their own extinct species, "Ictalurus decorus" Smith, 1961, but later studies have found these remains to fall within the range of morphological variation of the modern channel catfish, and it has thus been synonymized with it.

Channel catfish are native to the Nearctic realm and are widely distributed in southern Canada, the eastern and northern United States, and parts of northern Mexico.

They have an extensive native range consisting of almost all of the United States west of the Appalachian Mountains and east of the Rocky Mountains, roughly following the Mississippi River Basin. They are also native to peninsular Florida. They have also been widely introduced to Atlantic-draining rivers east of the Appalachians and Pacific-draining rivers west of the Rockies, giving them a continent-spanning range. Although they are officially considered introduced to this region, it has been suggested that they may also be native to the Atlantic-draining rivers from the Susquehanna south to the Neuse. Its range in southern Canada includes the Great Lakes (excluding Lake Superior) and parts of the Quebec, Ontario, and Manitoba provinces.

They have also been introduced into some waters of the Czech Republic and Romania, as well as parts of Malaysia and Indonesia.

This species thrives in rivers, reservoirs, lakes, and ponds. Channel catfish are cavity nesters, which means that they lay their eggs in crevices, hollows, or debris to protect them from swift currents.

Channel catfish have a well developed sense of smell and taste. Their nostril pits (nares) contain sense organs with high concentrations of olfactory receptors. In channel catfish, these organs are sensitive enough to detect several amino acids at about one part per 100 million in water. Also, the channel catfish has taste buds distributed over the surface of its entire body. These buds are especially concentrated on the four pairs of barbels (whiskers) surrounding the mouth, which have about 25 buds per square millimeter. This combination of strong senses of taste and smell allows the channel catfish to find food in dark, stained, or muddy water with relative ease. They also possess a Weberian apparatus, which amplifies sound waves that would otherwise not be perceptible. There is a misconception that the barbels of channel catfish sting upon contact. The barbels lack such capabilities and cannot sting. However, these catfish do have spines on their pectoral and dorsal fins which can inject venom and may cause injury if the fish is handled improperly.

An average adult channel catfish measures at least 12 inches (30 centimeters) long, and weighs between 2 and 4 pounds. The largest specimen on record weighed 58 pounds and was caught in 1964 by an angler in South Carolina.