It is a general term for the order Silurus. Catfish is closely related to fat carp, carp and minnows, and can be classified as Ostriniformes together. Another classification system is divided into CYPRINIDAE or Skeletonema, Silurus and CYPRINIDAE. Catfish is commonly known as catfish because it has a long beard around its mouth, which is very similar to the hair on the tip of a cat's kiss. The palate has at least one pair of beards, one on the snout and the other on the chin. Many catfish have hard spines on the dorsal fin and the front of pectoral fin, which are connected with poisonous glands and are very stinging. Smooth or scaleless, there are about 2500 species of catfish in 30 families.