They are called catfish because their barbels look like the whiskers of a cat. They are very diverse. The heaviest is the Mekong giant catfish, up to 350 kg (770 lb). The longest is the wels catfish, up to 4 m (13 ft). There are also detrivores in the group. There are some tiny parasitic catfish called candiru. Some catfish are grown for food, in fish farms. Some catfish can be kept in aquaria.