The catfishes group is an incredibly diverse group of mainly freshwater fish. There are over 2400 species in 33 families, only 2 of those families contain species that may be found in salt water. Catfishes are recognizable by their smooth, almost scaleless skin, and the sets of barbels (or whiskers) on their faces. These barbels are used to sense their environment through touch and chemical cues, like using their barbels as a set of noses. Catfishes are often found in slow-moving water and eat a large variety of foods. Most catfish species are found in tropical freshwater environments, with the largest number of catfish species being found in Central and South America. The catfishes group includes many fish that are economically important to humans, supporting both small scale and large-scale fisheries. Some catfish species grow to be very large, up to 2.7 meters (9 feet) long and 293 kilograms (646 pounds), although most species are small to medium sized. Some catfish species can produce strong electric pulses that they use to kill prey.
Tanya Dewey (author), Animal Diversity Web.