Endemic species
A species found naturally in only one place, such as one lake, one river system or one island.
Also: endemism
An endemic species lives naturally in one area and nowhere else. Lakes and rivers isolated for a long time often have many: most of Lake Malawi's cichlids are found only there, and the Western Ghats of India hold many freshwater fish found nowhere else, such as the Denison barb and the hump-backed mahseer of the Kaveri. Cave fish and desert pupfish can be endemic to a single pool. Small ranges make endemic fish vulnerable, because one dam, spill or introduced predator can wipe out the whole species.