The cutthroat trout is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the many fish species colloquially known as trout.
Cutthroat trout are native to western North America. Some (anadromous) populations live primarily in the Pacific Ocean as adults and return to fresh water from fall through early spring, to feed on freshwater insects and to spawn. Most populations, however, stay in freshwater throughout their lives and are known as non-migratory, stream-resident or riverine populations. Anadromous fish may reach weights of 20 pounds (9 kg) but those fish which remain permanently in freshwater may only reach a weight of 2 pounds (1 kg). At least three subspecies are confined to isolated basins in the Great Basin and can tolerate saline or alkaline water. All subspecies of cutthroat trout are sought after gamefish, especially among anglers who enjoy fly fishing.
Cutthroat will readily interbreed with the closely related rainbow trout, producing fertile hybrids. Cutthroat trout vary widely in size, coloration, and habitats. Though their coloration can range from golden to gray to green on the back, depending on subspecies and habitat, all populations feature distinctive red, pink, or orange marks on the underside of the lower jaw; usually the easiest diagnostic of the species for the casual observer. As adults, different populations and subspecies of cutthroat can range from 6–40 inches (3–100 cm) in length making size an ineffective indicator as to species.
