There are 15 species of trout, which predominately are freshwater fish. After maturing, many male and female trout return to the same place they were hatched in order to spawn. Most breed in early spring in running water. One of the best known trout is the brown trout, or sea trout, of Europe. They keep to the deeper pools and overhanging shelter of mountain streams. One of the most popular game fish is the rainbow trout, several forms of which are native to American Pacific Coast streams.