Siluriformes is an order of bony fish that includes all types of catfish. The name catfish refers to species with long antennae, or tentacles on the fish's mouth and resembling a cat's whiskers. All catfish have at least one pair of antennae on the upper jaw, with many spines in front of the dorsal and pectoral fins. Catfish include nearly 2,900 species and are in about 35 families. Most species live in fresh water, but there are some species that live in the sea (salt water). Catfish are generally bottom-dwelling species, and are more active at night than during the day.

The order Siluriformes includes the family Ictaluridae, the North American catfish, which includes the forked-tailed catfish (Ictalurus punctatus) and the blue catfish (Ictalurus furcatus), the major farmed American fish, and the flathead catfish (Pylodictis olivaris). . Other American species in the family Ictaluridae include the white catfish (Ameiurus catus), and the black, brown, and yellow bullhead catfish (Ameiurus melas, Ameiurus nebulosus, and Ameiurus natalis). In addition, in the order Siluriformes there are catfish of the family Clariidae, including Clarias fuscus, a Chinese species cultured on a small scale in Hawaii (ITIS).

Another family of the Siluriformes, Pangasidae, known as the "giant catfish," includes farmed basa (Pangasius bocourti), and pangasius (Pangasius hypophthalmus; or Pangasius sutchi), cultured mainly in Southeast Asia. for domestic consumption and export. Other commercially farmed catfish in Asia include the hybrid C. macrocephalus and also the North American catfish (I. punctatus).