Gem Tang

Geographical Origin and Habitat: Western Indian Ocean. A rare species inhabiting deep coral reefs, rocky areas exposed to strong currents, and vertical drop-offs between 10 and 60 meters.

Taxonomy and Morphology: Member of the family Acanthuridae. Reaches about 22 cm. Disc-shaped, highly compressed body typical of Zebrasoma, with a prominent snout and sail-like dorsal fin.

Social Behavior: Active and territorial fish. Dominant individuals defend large algal feeding territories. In the aquarium, it shows strong intolerance toward similar tankmates.

Coloration and Sexual Dimorphism: Stunning coloration: velvet-black body speckled with hundreds of small, sparkling silver-white spots. Pectoral and caudal fins are bright yellow. No dimorphism.

Aquarium Setup: Large tank of at least 680 liters (180 gallons) to ensure swimming space. Plenty of live rock arranged in a barrier rich in natural algal growth.

Diet and Feeding: Specialized herbivore. Diet must be heavily plant-based: nori, spirulina, surgeonfish pellets, and live macroalgae. Supplement occasionally with mysis.

Water Quality: Temperature 22-28°C (72-82°F), pH 8.1-8.4, specific gravity 1.020-1.025. Demands powerful skimming and strong water movement for high oxygenation.

Compatibility and Cohabitation: 100% reef-safe. Does not touch hard or soft corals. Avoid housing with other Zebrasoma surgeonfish to prevent fatal fights.

Aquarium Breeding: Reproduction in the home aquarium is extremely complex and undocumented due to the very long pelagic larval phase.

Risks and Diseases: Equipped with a sharp, retractable bony scalpel on both sides of the tail base. Exercise caution during handling. Highly sensitive to Velvet disease.