The Gem Tang (Zebrasoma gemmatum) is among the most coveted surgeonfish in the hobby, instantly recognizable by a jet-black body peppered with small white spots that grow denser and more intricate as the fish matures. Yellow edging traces the dorsal and anal fins, and yellow accents mark the tail. Juveniles arrive without the vivid adult patterning, which develops with age. The species is restricted to the Western Indian Ocean, concentrated around Mauritius, Madagascar, and Réunion, where it occupies deeper reef zones, open reef faces, and mixed sand-and-rubble areas adjacent to hard structure, frequently in surge-swept water. Adults reach roughly 9 inches.

Adult housing begins at a 180-gallon aquarium with a footprint of at least four to six feet, since this is a powerful, near-constant swimmer that grazes across large areas throughout the day. Build the rockscape generously: abundant live rock supplies grazing surface, refuge, and defensible territory, while strategically placed visual barriers reduce territorial friction. Strong flow, high oxygenation, and quality lighting mirror the conditions of the natural habitat and help sustain both the fish and the algal film it works over. Stability matters more than anything else here. Only a mature, fully cycled system with consistently high water quality should be considered, and introduction should be slow and deliberate to limit stress. Care is genuinely difficult, and a quarantine period before the display is strongly advised because transit stress leaves imported specimens vulnerable to parasites such as Cryptocaryon irritans, weight loss, and feeding inhibition. Handle with care at all times, as surgeonfish carry sharp caudal peduncle scalpels.