Skin of fish - delimit the body of fish from the external environment. Perform the functions of defense, respiratory, excretory, secretory, sensory, and sensory organ. In the skin of fish distinguish two layers: epidermis and a layer of connective tissue cells - the skin proper or cornum (dermis, cutis). Epidermis is multilayered, the shape of cells and the number of layers varies in different species of fish, contains pigmented, luminous cells or organs (in deep-sea fish), poison glands in some fish (borolavtchatka, sea dragon) and a large number of mucous cells (60-calovid, bulbous, granular). The corium consists of several layers of connective tissue (three in bony fish), penetrated by nerves and blood capillaries. In the same layer are pigment cells that determine the coloration of fish, and scleroblasts, specialized cells that secrete a secretion, which, cooling, forms scales.