Powder blue tang
Acanthurus leucosternon
The powder blue tang forms large schools in the Indian Ocean, grazing on sunlit reef flats. It is an active swimmer needing strong tidal currents and extensive algae cover.
Water Temperature
23 - 28 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
All levels
Adult size
23 cm
Minimum tank volume
>= 470 L
Minimum group
>= 1
KH
8 - 12 dKH
Species description
Geographical Origin and Habitat: Acanthurus leucosternon is widely distributed in the tropical waters of the Indian Ocean, from the coast of East Africa and Madagascar to western Indonesia. It inhabits shallow coral reefs, reef flats, and seaward slopes exposed to strong tidal currents, at depths ranging from 1 to 25 meters. They are often found in large schools grazing on sunlit rocks covered in filamentous algae.
Taxonomy and Morphology: Belonging to the family Acanthuridae and the genus Acanthurus. It features an oval, laterally compressed body with a small mouth adapted for scraping algae. It possesses sharp, retractable spines on both sides of the caudal peduncle, which are held flat against the body and raised only for defense or territorial battles. Adult specimens typically reach a maximum length of 20 to 23 centimeters.
Social Behavior: A semi-aggressive and highly territorial species. It shows intense intolerance toward conspecifics and other members of the genus Acanthurus, leading to serious fights. It is active during the day, swimming constantly throughout the aquarium to establish dominance. It should be introduced only into well-established tanks.
Coloration and Sexual Dimorphism: The coloration is exceptionally striking: a vibrant sky-blue body, a black head, and a distinct white chest and throat (hence 'leucosternon'). The dorsal fin is bright yellow, while the anal and pelvic fins are white. The caudal fin is blue with a black crescent margin. There is no visible sexual dimorphism between males and females.
Care, breeding and tankmates
Aquarium Setup: Requires an aquarium of at least 450-500 liters (approx. 120 gallons) with a minimum length of 150 cm to provide sufficient swimming space. The aquascape should feature plenty of live rock arranged with caves and swim-throughs, but keeping the front area clear. Powerful wavemakers are essential to provide strong water circulation and high oxygen levels.
Diet and Feeding: A specialized herbivore. Requires a diet rich in marine algae: feed dried seaweed (nori) daily, along with spirulina-based flakes, pellets, and herbivore preparations enriched with vitamins. Frozen foods (mysis, brine shrimp) are accepted but should only serve as occasional supplements. Proper nutrition is critical to maintain its immune system.
Water Quality: Extremely demanding. Requires absolute stability and clean water. Ideal parameters: temperature 23-26°C (73-79°F), pH 8.1-8.4, specific gravity 1.023-1.025, and carbonate hardness (KH) at 8-11 dKH. Nitrate and phosphate levels must be kept near zero using an oversized protein skimmer and regular water changes. An inline UV sterilizer is highly recommended.
Compatibility and Cohabitation: Should be kept as the sole surgeonfish in the aquarium unless the tank is exceptionally large. It cohabitates well with peaceful or semi-aggressive reef fish such as clownfish, anthias, small wrasses, and gobies. Avoid keeping it with other Acanthurus species or shy fish that might be stressed by its fast swimming.
Aquarium Breeding: Spawning in home aquariums is not documented due to the complex pelagic larval stage. In nature, they spawn in pairs or large groups at dusk, releasing eggs and sperm into the water column where the currents disperse the buoyant eggs until they hatch.
Risks and Diseases: Widely known as an 'ich magnet'. It is highly susceptible to Marine Ich (Cryptocaryon) and Velvet (Oodinium); any stress or temperature fluctuation will trigger infections. It is also prone to Head and Lateral Line Erosion (HLLE) under poor water quality or inadequate diet. Strict quarantine is mandatory.
Geographic Origin and Distribution
Acanthurus leucosternon is widely distributed in the tropical waters of the Indian Ocean, from the coast of East Africa and Madagascar to western Indonesia. It inhabits shallow coral reefs, reef flats, and seaward slopes exposed to strong tidal currents, at depths ranging from 1 to 25 meters. They are often found in large schools grazing on sunlit rocks covered in filamentous algae.
Origin
Cosmopolitan or introducedAfrica and MadagascarSouth and Southeast AsiaTropical oceans and reefs
Fish profile
- Temperament
- Aggressive
- This species is known for its highly territorial and aggressive behavior, especially toward other tangs or fish with a similar body shape. Once established, it will actively defend its territory and may bully new additions to the tank. It is crucial to monitor its behavior and introduce it as the final resident of the aquarium to minimize territorial disputes. Providing ample rockwork and multiple hiding spots can help diffuse potential territorial tension.
- Diet
- Herbivore
- The powder blue tang is primarily a herbivore that feeds on benthic algae in the wild. In captivity, its diet must consist majorly of marine plant matter, such as Nori seaweed sheets and spirulina-based flakes or pellets. While they will accept meaty foods like mysis and brine shrimp, these should only be offered as occasional treats. Providing high-quality seaweed enriched with vitamins is crucial to prevent head and lateral line erosion (HLLE) and maintain their vibrant colors.
- Life expectancy
- 10-15 years
- Under optimal aquarium conditions, the powder blue tang can achieve a lifespan of 10 to 15 years. Achieving this longevity requires strict water parameters, high dissolved oxygen, and a specialized diet. They are highly susceptible to skin parasites and bacterial infections, which can significantly shorten their lives if not addressed early. Long-term success is typically reserved for experienced aquarists who maintain stable, mature reef environments.
- Adult size
- 23 cm
- The catalog's scalar value is 23 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 54 cm for this species, recorded as total length (TL). The taxonomic record consulted is Acanthurus leucosternon (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Solitary
- Visual sexual dimorphism is not present in this species, making it difficult to distinguish males from females. In the home aquarium, it is strongly recommended to keep only a single specimen of this species to prevent severe intraspecific aggression. Attempting to keep multiple individuals or pairs requires an exceptionally large tank with numerous visual barriers. In the wild, they may form large feeding schools, but in captivity, individual housing is the standard.
- Feeding frequency
- Twice daily
- Due to its high energy levels and rapid metabolism, this species should be fed multiple times a day. Ideally, offering small portions two to three times daily keeps their digestive system working properly and helps reduce territorial aggression. Additionally, using a seaweed clip to leave a sheet of Nori in the tank allows them to graze naturally throughout the day. Consistent feeding is vital for maintaining their body weight and overall immune system health.
- Bioload
- High
- The powder blue tang has a high bioload because it is an active swimmer with a high metabolism that requires frequent feeding. Consequently, it produces a significant amount of biological waste, demanding a robust filtration system. A high-capacity protein skimmer and regular water changes are essential to maintain low nitrate and phosphate levels. Proper waste management is critical, as this species is highly sensitive to poor water conditions.
- Flow
- Strong
- Originating from shallow, turbulent reef crests, the powder blue tang requires strong water flow and high dissolved oxygen levels. The aquarium should be equipped with powerful wavemakers to simulate these high-energy marine environments. Excellent flow not only keeps the fish active and healthy but also helps keep detritus in suspension for filtration. Insufficient water movement can cause stress, respiratory issues, and make them more vulnerable to diseases.
- Jump risk
- Yes
- Although not classified as chronic jumpers, powder blue tangs are very easily startled and can jump out of the tank when spooked. Sudden lighting changes, aggressive tank mates, or external movements near the glass can trigger a flight response. A tight-fitting lid or a secure mesh cover is highly recommended to prevent accidental leaps. Ensuring a calm environment and using a gradual dimming system for lights can significantly reduce this behavior.
- Reproduction
- Oviparous
- Breeding the powder blue tang in captivity is exceptionally difficult and is rarely achieved by private aquarists. In the wild, they are broadcast spawners that release their gametes into the water column in synchronized group events. The resulting larvae undergo a long and complex planktonic stage that is extremely hard to replicate in a closed system. Almost all specimens available in the aquarium trade are wild-caught, though ongoing aquaculture research aims to change this.
- Compatibility & tankmates
- Aggressive
- This tang is highly aggressive toward other surgeonfishes, particularly those of the same genus or with similar coloration. It is best housed with semi-aggressive, active tank mates such as wrasses, large clownfish, triggerfish, and large damselfishes. Avoid keeping it with peaceful, slow-moving species that can easily be intimidated by its rapid swimming and territorial nature. In very large systems, it can sometimes be housed with other tangs if introduced carefully and simultaneously.
- Tank level
- All levels
- This species is an active, open-water swimmer that utilizes all levels of the aquarium, though it spends most of its time in the middle and upper zones. It requires a vast amount of open swimming space to satisfy its constant active movement. While it patrols the open water during the day, it will retreat into the lower rockwork at night for shelter and sleep. Providing a balance of open swimming lanes and complex rock structures is crucial for its well-being.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2 ± 0 se
- Resilience
- Medium (1.4 - 4.4 years)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.02042, b = 2.94
- VulnerabilityModerate vulnerability (42 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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