Clupeidae is the family of the herrings, shads, sardines, hilsa and menhadens. It includes many of the most important food fishes in the world.
Clupeids are mostly marine forage fish, although a few species are found in freshwater. No species has scales on the head, and some are entirely scaleless. The lateral line is short or absent, and the teeth are unusually small where they are present at all. Clupeids typically feeds on plankton, and range from 2 centimetres (0.79 in) to 75 centimetres (30 in) in length.
Clupeids spawn huge numbers of eggs (up to 200,000 in some species) near the surface of the water. After hatching, the larvae live among the plankton until they develop a swim bladder and transform into adults. The adults typically live in large shoals.