Cotylopus Climbing Goby

Cotylopus acutipinnis is a rare and beautiful amphidromous goby found exclusively on the islands of Réunion and Mauritius in the Indian Ocean, where it inhabits fast-flowing volcanic mountain streams and cascades. Its name refers to the sharply pointed dorsal, anal, and pelvic fins, which combined with its powerful suction disc allow it to scale near-vertical rock faces and climb waterfalls to reach its upstream adult habitat. Body colouration is an elegant olive-green to tan with subtle lateral banding and iridescent scale highlights. Males develop more vivid colouration and larger fins. As with all island stream gobies, it requires pristine, highly oxygenated water and a mature biofilm-covered substrate. This is a specialist fish for experienced aquarists interested in Indian Ocean island biotopes.

Water: 20–26 °C, pH 7.0–7.8, GH 5–15, KH 3–10; very high dissolved oxygen and strong flow required. Tank: 80 L minimum; volcanic or smooth river rock arranged in riffle zones; mature periphyton biofilm essential. Feeding: Aufwuchs grazer; spirulina wafers, blanched greens, and Repashy gel foods; does not require animal-based foods. Breeding: Amphidromous; marine larval phase; not bred in captivity. Compatibility: Peaceful; best with other hillstream species; avoid competitive algae-grazers that deplete biofilm.