Any of certain species of small (6–12 in., or 15–30 cm, long) food fishes of the herring family (Clupeidae), especially in the genera Sardina, Sardinops, and Sardinella. The common herring (Clupea harengus) is found throughout the North Atlantic. The five species of Sardinops live in the Pacific and Indian oceans. Sardines are small, silvery, slender fishes with a single short dorsal fin and no scales on the head. They live in dense schools, migrating along the coast. They are usually fished with an encircling net, particularly the purse seine, and mainly at night, when they surface to feed on plankton. See alsopilchard, sprat.