Type locality of Rhinogobius tandikan, northern Puerto Princesa City, Bahile, Cayulo River. This species is found only in the Cayulo River which is a small stream (length approximately 4 km including 1 km of an estuary) flowing into Ulugan Bay on South China Sea-side of the island. The stream system is surrounded by mountains of about 200-400 m above sea level. The Cayulo Falls is composed of a series of small waterfalls, located at the middle reaches of this stream (10°02'12"N 118°45'03"E). The species was found at both the lower and upper reaches of this waterfall, as well as pools in the middle of the falls. It was abundant in this site with many other goby species, cyprinids, and a jungle perch species (Ref. 125663).