This order of ray-finned fish, Salmoniformes, includes about 66 species of salmon, trout, whitefish, and their close relatives, all in a single family, Salmonidae.

These fish usually live in freshwater or in both freshwater and the ocean, mostly in temperate and subarctic regions of the Northern Hemisphere. Many salmoniform fish are famous for their incredible long-distance swimming abilities—especially salmon, which return from the ocean to the rivers where they were born to lay their eggs.

Salmoniformes usually have slim, streamlined bodies that help them move quickly through currents. (The name Salmoniformes literally means “salmon-shaped.”) Their fins are soft and flexible, and their scales glint in the water. Most of these fish are carnivores, feeding on smaller fish, insects, and other tiny aquatic animals.