-Non-indigenous fish species (i.e., those not native to the area) include both exotic species (i.e., those from a foreign land) and non-native species (i.e., those that have expanded beyond their native range) and they often adversely affect valued native fish populations. Non-indigenous species often compete with or prey upon commercially or recreationally important fish species. They may also hybridize with closely related native species and cause a distortion in the gene pool.