Voracious freshwater fish (Amia calva) that is the only living representative of the family Amiidae, which dates back to the Jurassic period (206–144 million years ago). It is found in sluggish North American waters from the Great Lakes southward to the Gulf of Mexico. Mottled green and brown, it has a long dorsal fin and strong conical teeth. The female, which is larger than the male, reaches a length of 30 in. (75 cm). The bowfin spawns in spring, when the male constructs a crude nest and guards both the fertilized eggs and the newly hatched young. It is sometimes called a dogfish.