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Gem Tang (Zebrasoma gemmatum)

Gem Tang

Zebrasoma gemmatum
Family
Tang
Care level
Advanced
Temperament
Semi-aggressive
Reef safe
Reef safe
Max size
21 cm
Min tank
500 L · 132 gal
Origin
Western Indian Ocean (Mauritius, Comoros)
Diet
Herbivore
Food
Nori, Marine algae, Herbivore pellets, Spirulina, Vegetable frozen blends

Overview

The Gem Tang is one of the most sought-after and expensive tangs in the hobby, prized for its deep charcoal-black body covered in small pale gold spots that give it a jewelled appearance. Its rarity comes from a limited collection range restricted to a small area of the Western Indian Ocean, which keeps supply low and prices high.

Despite its exclusivity, its care requirements are broadly similar to other Zebrasoma tangs — it needs a well-established tank, strong water quality, and a diet centred on marine algae. It's not inherently more difficult to keep than other mid-sized tangs, but its cost means most keepers only attempt it once other tangs have been kept successfully.

Given its price point, buyers should be confident in their system's stability and their supplier's health guarantee before purchasing.

Compatibility

Gem Tangs can be territorial toward other tangs, particularly other Zebrasoma species, so care with stocking order and tank size matters if keeping multiple tangs. They are generally peaceful with unrelated community fish.

This species is fully reef safe and won't bother corals, clams, or invertebrates.

Health & quarantine

Given the expense involved, quarantine is essential rather than optional — a minimum four-week period with close observation for ich and stress-related symptoms is strongly recommended. Buying from a reputable supplier who can confirm the fish is eating well and has cleared an initial holding period significantly reduces risk with this high-value species.

Frequently asked questions

Why is the Gem Tang so expensive?
It comes from a very limited collection area in the Western Indian Ocean, which keeps supply low relative to demand.
Is the Gem Tang harder to keep than other tangs?
Not inherently — its care needs are similar to other Zebrasoma tangs, though its high cost means mistakes are more costly.
Is the Gem Tang reef safe?
Yes, it's herbivorous and won't bother corals or invertebrates.
What tank size does a Gem Tang need?
At least 500 litres given its adult size and need for swimming space.
Should I quarantine a Gem Tang?
Absolutely — given the cost involved, a full four-week quarantine with careful observation is strongly recommended rather than optional.

Care guidance is drawn from our own experience — every fish is an individual, so treat it as a starting point, not a guarantee. Not sure if a species suits your tank? Come ask us in store. New to the terms? Read the care-terms glossary.