Characteristics
The species of Clupea belong to the larger family Clupeidae (herrings, shads, sardines, menhadens), which comprise some 200 species that share similar features. These silvery-colored fish have a single dorsal fin, which is soft, without spines. They have no lateral line and have a protruding lower jaw. Their size varies between subspecies: the Baltic herring (Clupea harengus membras) is small, 14 to 18 centimeters; the proper Atlantic herring (C. h. harengus) can grow to about 46 cm (18 inches) and weigh up 700 g (1.5 pounds); and Pacific herring grow to about 38 cm (15 inches).
Read more about this topic: Herring