Catfish are any of about 31 families and 2,000 species of fish, most of which are found in freshwater. They are distributed throughout the world. Their distinguishing feature is the presence of barbels, or "whiskers," the lack of true scales, and strong spines at the front of the caudal fin. Many freshwater catfish species are used for human food. North American catfish of the genus Ictalurus are both popular with angler and important commercially. Catfish farming, which consists of raising and marketing the fish, is a rapidly growing business in many parts of the United States.