Catfish are a diverse group of ray-finned fish of the order Siluriformes. Catfish are named for their prominent barbels, which resemble a cat's whiskers, though not all catfish have prominent barbels. All Siluriformes lack scales, instead possessing either smooth skin or armour-plated bodies. This order of fish are defined by features of the skull and swimbladder. Catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia, and the piraíba of South America, to detritivorous and scavenging bottom feeders, down to the tiny ectoparasitic species known as the candiru.
