Gem Tang EXPERT (Zebrasoma Gemmatum)

Also Known As: Gemmatum Tang

Compatibility and Behavior
The Gem Tang (Zebrasoma gemmatum) is one of the true grail fish of the hobby, prized as much for its rarity as for the dramatic contrast it brings to a high-end display. The deep, inky-black body is dusted with countless tiny white to yellow "star" spots, while the tail and rear of the dorsal fin glow a rich golden yellow, giving the whole fish a jewel-like quality that almost guarantees it becomes the focal point of the tank. Add the classic Zebrasoma disc-shaped body and sail-like dorsal fin, and you've got a fish that genuinely looks designer. On temperament, Gem Tangs tend to be peaceful to semi-aggressive and behave a lot like Yellow and Purple Tangs, with most of their attitude reserved for other Zebrasoma or similarly shaped tangs. They're typically considered reef safe, spending the bulk of the day grazing film and filamentous algae off rock and hard surfaces rather than picking at corals or ornamental inverts. With thoughtful stocking, room to roam, and steady access to algae-rich foods, they usually settle in well alongside a wide range of community fish like clownfish, wrasses, Anthias, and fairy basslets.

Aquarium Requirements
Gem Tangs do best in larger, mature reef systems with long horizontal swimming space and plenty of established live rock to graze. For medium specimens in the 3 to 3.5 inch range, a tank around 120 gallons or larger with a long footprint is the right target, with even more space preferred for large and XL individuals. Aquascape with open cruising lanes and a solid rock structure featuring arches, ledges, and shaded retreats where the fish can wedge in at night or when startled. Strong, well-oxygenated flow, high-quality filtration, and stable parameters all matter, both for overall health and to fuel that constant grazing behavior. Frequent feedings of nori, marine algae, and varied herbivore foods will help them hold their body weight, curb aggression, and keep that spotting and yellow tail looking vivid.

Specifications
Approximate Size: Md: 3–3.5", Lg: 3.5–4.5", XL: 4.5–5.5"
Diet: Primarily herbivorous. Marine algae, nori, and spirulina-based foods, with occasional frozen mysis shrimp
Origin: Western Indian Ocean, including Madagascar and surrounding island reef systems
Care Level: Expert
Reef Safe: Generally reef safe; focuses on algae and biofilm rather than corals
Temperament: Peaceful to semi-aggressive; may be territorial toward other Zebrasoma and similar grazers
Minimum Tank Size: Medium specimens can start around 120 gallons, with more space preferred for large and XL individuals
Special Considerations: A rare, high-value tang best kept in a mature, very stable system