Mangrove Whipray

Urogymnus granulatus is a large whipray distributed across the Indo-Pacific, from the Red Sea and Indian Ocean to the Western Pacific, commonly found in mangrove estuaries, tidal rivers, and — notably for aquarists — fully freshwater sections of larger river systems. Its dorsal surface has a distinctively rough, granular texture due to denticles covering the disc, setting it apart from smooth-skinned potamotrygonids. It is euryhaline and adapts to fully fresh water with careful acclimatisation. In captivity it requires large, well-filtered tanks, a diet of meaty marine invertebrates and fish, and stable water chemistry. Far less often kept than South American rays, it offers a geographically and taxonomically distinct option for the specialist elasmobranch keeper.

Water: 24–28°C, pH 6.5–8.0, moderate to moderately hard (5–18 dGH); zero ammonia/nitrite; large water changes. Tank: Minimum 800L, fine sand, wide open base; maintain as freshwater but near-neutral to slightly alkaline conditions. Feeding: Carnivore; prawn, mussel, squid, crab, whitebait; does not accept freshwater invertebrates as readily initially. Breeding: Viviparous; no captive freshwater breeding records; euryhaline breeding biology unknown. Compatibility: Large, robust fish only; avoid anything that will investigate or nip the disc.