Gem Tang
Zebrasoma gemmatum
Also known as Gem Surgeonfish, Spotted Tang, Jewel Tang
Care at a glance
- Temperature
- 75–81°F (24–27°C)
- pH
- 8.1–8.4
- Adult size
- 8.7 in (22 cm)
- Minimum tank
- 151 gal (570 L)
- Temperament
- Mostly peaceful
- Social behavior
- Solitary
- Swim level
- Middle
- Difficulty
- Medium
- Breeding
- No record
- Rarity
- Rare
- Reef safe
- Reef safe
- Origin
- Western Indian Ocean around Mauritius, Reunion, Madagascar and South Africa, on rocky and coral reefs.
- Family
- Acanthuridae
Overview
Keep a gem tang in at least 570 litres with plenty of rock for grazing and open water for swimming, at 24 to 27 C and pH 8.1 to 8.4. It is reef safe and works well in a mixed reef, but house only one Zebrasoma per tank to avoid fighting. Feed dried seaweed, spirulina and marine algae daily with some meaty foods. It is generally hardy once settled, which helps justify the high purchase price.
In the wild
The gem tang is a deep-bodied Zebrasoma covered in white spots on a black body, from the deeper reefs of the western Indian Ocean. It grazes algae from rock and moves in a slower, more deliberate way than the long unicornfish. Wild collection is difficult, which keeps it scarce and expensive. It is territorial toward other tangs but calm with most other fish.
Good to know
Zebrasoma gemmatum reaches about 22 cm and is one of the most prized surgeonfish in the trade. Its range around Mauritius, Madagascar and South Africa is small and hard to reach. Like other Zebrasoma it has a tall dorsal and anal fin profile.
Did you know
Its high cost comes from geography, since the reefs it lives on are remote and rough, not from any special difficulty in keeping it.
Where to buy
Some links may not be the exact species or variety.
…or ask your local fish store.
Appears in
Keeping Gem Tang?
Track water tests, reminders and stocking fit.
Related species

Black Tang
Zebrasoma rostratum8.3 in (21 cm)119 gal (450 L)75–81°F (24–27°C)
Scopas Tang
Zebrasoma scopas7.9 in (20 cm)90 gal (340 L)75–82°F (24–28°C)
Yellow Tang
Zebrasoma flavescens7.9 in (20 cm)100 gal (380 L)72–79°F (22–26°C)
Purple Tang
Zebrasoma xanthurum9.8 in (25 cm)106 gal (400 L)75–82°F (24–28°C)
Sailfin Tang
Zebrasoma veliferum11.8 in (30 cm)145 gal (550 L)75–82°F (24–28°C)
Red Sea Sailfin Tang
Zebrasoma desjardinii15.7 in (40 cm)180 gal (680 L)75–82°F (24–28°C)
