Description
The Gem Tang (Zebrasoma gemmatum), also known as the spotted, jewelled, or Mauritian tang, is a prized marine surgeonfish from the family Acanthuridae.
Appearance and Size
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Body Shape: Tall, disc-shaped, laterally compressed body with a short/deep profile, an elongated snout used for grazing, and a sharp caudal (tail) defensive spine.
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Coloration: Deep black to dark brown body covered in numerous small, jewel-like white or yellow speckles, paired with a bright yellow caudal fin.
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Size: Grows to a maximum total length of about 20 to 22 cm (8.7 inches).
Habitat and Distribution
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Geographic Range: Native to the Western and Southwestern Indian Ocean, including waters off Mozambique, South Africa, Madagascar, Réunion, and Mauritius.
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Depth & Environment: Inhabits coral and rocky reefs at depths ranging from 10 to 61 meters (usually found deeper at 25 meters or more), with juveniles residing in shallower waters.
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Conservation Status: Listed as Data Deficient (DD) on the IUCN Red List.
Behavior and Diet
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Diet: Primarily herbivorous, grazing continuously on marine algae and microalgae.
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Temperament: Solitary, shy, and highly territorial in the wild; can display aggression toward other tangs or similarly shaped fish in an aquarium setting.
Aquarium Care
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Care Level: Moderate.
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Minimum Tank Size: Requires a large system—typically 500 liters (180 gallons) or more—with ample open swimming space, strong water flow, and live rock for grazing and hiding.
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Reef Compatibility: Considered reef-safe, though it is usually recommended to introduce them last or keep them as the sole Zebrasoma species to prevent territorial fights
