species of slab-sided, northern fish belonging to the family Clupeidae (order Clupeiformes). The name herring refers to either the Atlantic herring (Clupea harengus harengus) or the Pacific herring (C. harengus pallasii); although once considered separate species, they are now believed to be only subspecifically distinct. Herrings are small-headed, streamlined, beautifully coloured fish with silvery iridescent sides and deep-blue, metallic-hued backs. Adults range from 20 to 38 centimetres (8 to 15 inches) in length. One of the most abundant species of fishes in the world, herring eat such minute organisms as copepods, pteropods, and other planktonic crustaceans, as well as fish larvae. They travel in vast schools, providing food for larger predators such as cod, salmon, and tuna. Herrings may be caught with drift nets and surrounding nets (mostly seine nets or trawls). In Europe the majority of the herring catch is either salted, pickled in barrels, or cured by smoking and sold as kippered herring. In eastern Canada and the northeastern United States, most of the herring utilized are young fish, taken in inshore weirs or seines, that are canned as sardines. The bulk of the herring taken in the Pacific Ocean is used in the manufacture of fish oil and meal, and smaller quantities are pickled and smoked.

Herring spawn between December and midsummer, depending upon latitude and temperature. Each female deposits as many as 40,000 sticky eggs on seaweed or rocks; the eggs hatch in about two weeks. Herrings move shoreward to spawn, and after spawning, the schools of mature herrings disperse. The large herring fisheries are subject to great fluctuations in their annual catches because the survival of the populations of young herrings varies widely from year to year. The fish mature in about 4 years and may live 20 years.

In addition to other members of the genus Clupea (e.g., the bristling, or sprat), the term herring is applied to other members of the family Clupeidae, including the skipjack herring (Alosa chrysochloris) and the alewife (A., or Pomolobus, pseudoharengus). Various other, less common species in the family are also called herrings. The term herring is also used for certain fishes in families other than Clupeidae, such as the wolf herring (Chirocentrus dorab).