Catfish have one of the greatest ranges in size within a single order of bony fish. Some of the smallest species of Aspredinidae and Trichomycteridae reach sexual maturity at only 1 centimeter (0.39 in). The average size of the species is about 1.2–1.6 m (3.9–5.2 ft), and fish more than 2 meters (6.6 ft) are rare. However, they are known to exceed 2.5 meters (8.2 ft) in length and 100 kilograms (220 lb) in weight.

The name “catfish” refers to the long barbels, or feelers, which are present about the mouth of the fish and resemble cat whiskers.

The diet of catfish often changes as they age. Young catfish primarily feed on aquatic insects such as dragonfly larvae, water beetles and fly larvae. By the time they’re adults, catfish consume small fish, seeds, aquatic plants, algae, crawfish and snails.

Catfish can produce different types of sounds and also have well-developed auditory reception used to discriminate between sounds with different pitches and velocities. They are also able to determine the distance of the sound’s origin and from what direction it originated. Catfish are able to produce a variety of sounds for communication that can be classified into two groups: drumming sounds and stridulation sounds.