Acanthurus nigricauda — Epaniette Tang (also known as Epaulette Surgeonfish or Blackstreak Surgeonfish)
Family: Acanthuridae
Origin: Indo-Pacific — from East Africa to the central Pacific, including the Great Barrier Reef and Micronesia
Size: Up to 40 cm (16 inches)
Lifespan: 10–15 years in captivity
 
Natural Habitat
Environment: Coastal lagoons, reef flats, and outer reef slopes; often found in silty or sandy areas near reefs
Water Conditions: Warm, tropical marine environments with steady parameters
Temperature Range: 24–28°C (75–82°F)
 
Physical Description
Body Shape: Oval and laterally compressed
Coloration:
Pale gray to brownish body with a distinct black horizontal streak behind the gills ("epaulette" marking)
Faint vertical body banding may be visible in some individuals
Fins: Moderate dorsal and anal fins; sharp scalpel-like spine at base of tail
 
Aquarium Care
Tank Size: Minimum 180 gallons (680 litres) due to adult size and active nature
Water Parameters:
pH: 8.1–8.4
Salinity: 1.020–1.025 SG
Temperature: 24–28°C (75–82°F)
Water Flow: Moderate to strong
Substrate: Sand or crushed coral
Décor: Ample live rock for grazing, swimming space, and hiding
Filtration: High-performance filtration with strong biological support and protein skimming
 
Diet
Type: Omnivorous grazer
Preferred Foods:
Marine algae (nori, spirulina), seaweed-based pellets
Occasional protein: mysis shrimp, brine shrimp
Feeding Frequency: 2–3 times daily in small portions
 
Behavior & Tank Mates
Temperament:
Generally peaceful for its size, but may show territorial behavior to similar-shaped tangs
Active swimmer that requires room to roam
Compatible Tank Mates:
Reef-safe, peaceful to semi-aggressive fish (wrasses, angelfish, clownfish, gobies)
Avoid housing with other Acanthurus species unless tank is large and carefully planned
Behavior Notes:
Robust and hardy in large systems; less aggressive than some tangs
 
Breeding
Spawning Method: Broadcast spawner
Breeding Conditions:
Not bred in home aquariums; wild spawning occurs in groups
Fry Care:
Planktonic larvae require advanced marine hatchery systems