Gem Tang

Gem Tang

Also known as Gem Surgeonfish or Zebrasoma gemmatum.
The Gem Tang is a stunning reef tang distinguished by its rich, deep purple-blue body adorned with numerous small bright blue spots across the body, giving it a sparkling “gem-like” appearance. Native to the central Indo-Pacific region, including the Indian Ocean and Indonesia, this hardy tang is both visually striking and active, making it a favorite among experienced aquarists. Captive-bred Gem Tangs adapt well to aquariums and are an excellent choice for intermediate to advanced reef hobbyists seeking a unique centerpiece fish.

Key Features

Scientific Name: Zebrasoma gemmatum
Common Names: Gem Tang, Gem Surgeonfish, Spotted Surgeonfish
Adult Size: 10–12 inches (25–30 cm)
Lifespan: 8–12+ years with proper care
Temperament: Semi-aggressive; generally peaceful but may defend territory around other tangs
Reef Compatibility: Reef-safe 
Minimum Tank Size: 180 gallons
Experience Level: Intermediate 

Habitat & Tank Requirements

Natural Habitat: Found on outer reef slopes, channels, and lagoons at depths of 15–80 feet, primarily feeding on filamentous algae and detritus.

Tank Environment:

• Open swimming space is essential
• Moderate water flow to mimic natural currents
• Plenty of live rock for grazing and hiding
• Secure lid to prevent jumping
• Established aquariums recommended (3+ months)

Water Parameters:

• Temperature: 74–82°F (23–28°C)
• Salinity: 1.023–1.025 specific gravity
• pH: 8.1–8.4
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm
• Alkalinity: 8–12 dKH

Essential Equipment:

• Efficient protein skimmer
• Strong filtration system
• Moderate-to-strong lighting
• Regular water changes (10–15% weekly)

Diet & Feeding

Gem Tangs are primarily herbivorous but will accept prepared foods once acclimated.

Recommended Foods:

• Pellets/Flakes: Algae-based, spirulina, herbivore formulas
• Frozen Foods: Finely chopped marine algae, phytoplankton
• Plant Matter: Nori sheets, spirulina sheets
• Prepared Mixes: Herbivore blends, enriched frozen preparations

Feeding Schedule:

• Feed 2–3 times daily
• Offer portions they can consume in 2–3 minutes
• Variety ensures healthy digestion and maintains vibrant coloration

Behavior & Compatibility

Temperament: Peaceful with most species but may show territorial behavior toward other tangs

Tank Mates: Compatible with most peaceful reef fish including gobies, wrasses, blennies, and non-aggressive tangs. Caution with aggressive tangs or predatory species.

Pairing Behavior: Can be kept singly or in groups in large aquariums. Juveniles adapt more readily to community environments.

Reef Compatibility

• Completely reef-safe; will not harm corals or invertebrates
• Excellent choice for mixed reef aquariums

Acclimation & Care Tips

Initial Acclimation:

• Drip acclimation over 45–60 minutes
• Float bag for temperature equalization (15–20 minutes)
• Dim lights during introduction

Health Considerations:

• Susceptible to marine ich (Cryptocaryon) if stressed
• Quarantine for 2–3 weeks before adding to display tank

Signs of a Healthy Specimen:

• Active grazing and swimming
• Clear eyes and smooth fins
• Vibrant, uniform coloration with bright blue spots

Color & Development

Coloration Characteristics:

• Body: Deep purple-blue
• Spots: Numerous bright blue “gem-like” spots across the body
• Fins: Blue to purple with subtle darker margins
• Eyes: Clear and bright

Color Intensity:

• High-quality diet maintains vivid body and spot colors
• Proper lighting enhances contrast
• Stress or poor water quality may cause temporary fading

Size & Growth:

• Juveniles start at 3–4 inches
• Reach adult size (10–12 inches) within 18–24 months

Special Considerations

Quarantine is Recommended: Observed for parasites and disease, monitored for appetite and activity, conditioned to prepared aquarium foods.

Captive-Bred Advantages:

• Better adaptation to aquarium life
• Reduced disease risk
• More consistent coloration
• Stronger feeding habits

Breeding Potential:

Breeding Gem Tangs in captivity is rare. Spawning may occur in large, mature reef systems with optimal conditions, abundant grazing surfaces, and stable water quality. Raising larvae is complex and generally requires professional facilities.

Why Choose a Quarantined Gem Tang?

A fully quarantined Gem Tang offers better long-term success, fewer health issues, stronger feeding habits, and a smoother transition into your display tank, giving you confidence that your new tang will thrive and display its full sparkling “gem-like” colors in your reef system.