Either the Atlantic or the Pacific subspecies of Clupea harengus (once considered two separate species), slab-sided, northern fishes that are small-headed and streamlined, with silvery iridescent sides and a deep-blue, metallic-hued back.
The name also refers to some other members of the family Clupeidae. Adults range in length from 8 to 15 in. (20–38 cm). One of the most abundant species of fish, herring travel in enormous schools. They eat planktonic crustaceans and fish larvae. In Europe they are processed and sold as kippered herring; in eastern Canada and the northeastern U.S., most of the herring used are young fishes canned as sardines. Herring taken in the Pacific are used mainly to make fish oil and meal.