Three fih species are found in the American Fork River. In Timpanogos Cave National Monument, 2 species, Brown Trout and Rainbow Trout, are stocked by the Utah Division of Wildlife Resources.  Only one species, the Bonneville Cutthroat Trout, is native to the area.  Being pushed out by the more competitive exotic fish, Bonneville Cutthroat Trout only exists in the extreme upstream sections of the American Fork River.