Black Longnose Tang
Zebrasoma rostratum
The Black Longnose Tang is an exquisite, rare marine gem featuring a jet-black body and an elongated snout. It demands premium water quality and ample swimming space to browse gracefully on reef algae.
Water Temperature
22 - 28 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
All levels
Adult size
21 cm
Minimum tank volume
>= 680 L
Minimum group
>= 1
KH
8 - 12 dKH
Species description
Geographical Origin and Habitat: Tropical South Pacific. Inhabits outer reef slopes and deep lagoons rich in algal growth down to 35 meters. They are found in relatively clear waters, often on outer reef slopes exposed to constant oceanic waves.
Taxonomy and Morphology: Member of the family Acanthuridae. Reaches about 21 cm. Characterized by a very tall and compressed body, huge sail-like dorsal and anal fins, and a markedly elongated snout. The elongated snout is a key feature that distinguishes it from other Zebrasoma species, allowing access to deep rock crevices.
Social Behavior: Active and territorial fish. Constantly monitors the tank and vehemently defends algal grazing areas. Extremely territorial, they establish a dominance hierarchy in the tank and will show aggression toward potential competitors.
Coloration and Sexual Dimorphism: Entirely matte carbon-black or velvety pitch-black body. Displays a white scalpel on the caudal base. No externally visible sexual dimorphism. The contrast between the deep black body and the white caudal spine serves as a warning sign for other fish.
Care, breeding and tankmates
Aquarium Setup: Needs a spacious aquarium of at least 680 liters (180 gallons) with plenty of open swimming space and rocks arranged in a barrier rich in benthic algae. The tank should be styled with plenty of arches and caves to create territory markers and lower social stress.
Diet and Feeding: Herbivore. Diet must be based on dried seaweed (nori), spirulina, enriched veggie pellets, and fresh macroalgae. Feeding nori daily is essential to provide the high fiber content required for their digestive health.
Water Quality: Temperature 22-28°C (72-82°F), pH 8.1-8.4, specific gravity 1.020-1.025. Strong water movement and excellent skimming to maintain high oxygen levels. Excellent water flow and oxygenation are critical; a wavemaker should be positioned to create a steady surface current.
Compatibility and Cohabitation: 100% reef-safe. Does not touch corals. Strictly avoid housing with other Zebrasoma surgeonfish, especially black ones. They are safe with all types of corals, making them highly desirable for large reef aquariums.
Aquarium Breeding: Reproduction is not recorded in domestic captivity due to the complex pelagic larval phase. Due to their pelagic nature, rearing the fry is extremely hard and has only been achieved in professional facilities.
Risks and Diseases: Beware of the retractable caudal spine during maintenance. Sensitive to skin diseases under stress. They are highly susceptible to ich (Cryptocaryon) during the initial acclimatization phase, requiring a strict quarantine period.
Geographic Origin and Distribution
Tropical South Pacific. Inhabits outer reef slopes and deep lagoons rich in algal growth down to 35 meters. They are found in relatively clear waters, often on outer reef slopes exposed to constant oceanic waves.
Origin
Tropical oceans and reefs
Fish profile
- Temperament
- Territorial
- The Black Tang is considered semi-aggressive, particularly within the confines of an aquarium. While it generally ignores invertebrates and unrelated fish, it fiercely defends its grazing territory from perceived competitors. Its sharp caudal spines (scalpels) are effective weapons used during disputes. Providing a sufficiently large tank minimizes aggressive tendencies and promotes a harmonious community.
- Diet
- Herbivore
- The Black Tang is primarily herbivorous, needing a substantial amount of marine algae in its daily diet. It should be offered dried seaweed (nori) attached to a grazing clip to mimic natural feeding behaviors. While it enthusiastically accepts meaty foods like mysis or brine shrimp, lacking sufficient greens can lead to Head and Lateral Line Erosion (HLLE). Spirulina-enriched flakes or pellets can also supplement its nutritional requirements.
- Life expectancy
- 10-15 years
- This fascinating black surgeonfish can live between 10 and 15 years in the aquarium if it receives excellent care and is housed in a spacious environment. Its longevity depends on the stability of water parameters, the absence of stress, and a targeted plant-based diet. Being a prized and delicate species during the acclimation phase, proper initial management is essential.
- Adult size
- 21 cm
- The catalog's scalar value is 21 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 21 cm for this species, recorded as total length (TL). The taxonomic record consulted is Zebrasoma rostratum (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
- There is no easily distinguishable sexual dimorphism in the Black Tang. Both males and females share the same striking coloration and identical morphological features. In a home aquarium, maintaining a specific sex ratio is generally irrelevant since keeping multiple individuals is highly discouraged. For breeding facilities, genetic testing or behavioral observation is required to confirm the sexes.
- Feeding frequency
- Twice daily
- Because of its highly active nature, this species requires multiple feedings throughout the day. Offering small meals 2 to 3 times daily ensures its high metabolic demands are met. A constant supply of grazing material, such as live macroalgae or dried nori, should be available between structured meals. Underfeeding can rapidly lead to weight loss and a weakened immune system.
- Bioload
- The Black Tang (Zebrasoma rostratum) has a moderately high bioload typical of active surgeonfishes. It constantly grazes on algae and requires frequent feedings, which translates to a steady production of waste. A robust filtration system, including a high-capacity protein skimmer, is necessary to manage its biological impact. Regular water changes are also critical to ensure nutrient levels remain within safe parameters.
- Flow
- Strong
- Coming from turbulent reef environments, the Black Tang thrives in high flow aquarium setups. Strong water movement provides essential oxygenation and replicates the natural currents it encounters in the wild. Multiple powerheads or wavemakers should be positioned to create chaotic, multidirectional flow. This dynamic environment also encourages natural swimming and grazing behaviors across the rockwork.
- Jump risk
- No
- Reproduction
- Oviparous
- In the wild, Zebrasoma rostratum are pelagic spawners, releasing eggs and sperm into the water column during synchronized events. They form large breeding aggregations, usually coordinating with lunar cycles and outgoing tides. Captive breeding of this tang is extremely rare and difficult due to the complex requirements of raising their microscopic larvae. Most individuals available in the hobby are wild-caught from specific locales.
- Compatibility & tankmates
- Semi-aggressive
- This tang is generally peaceful toward most non-conspecific tank mates in a reef setting. However, it can become highly territorial and aggressive toward other surgeonfishes, especially those of the same genus or similar body shape. It is best kept as the solitary tang or introduced simultaneously with other tangs into a very large aquarium. Careful observation is required during the initial introduction to mitigate severe aggression.
- Tank level
- All levels
- This species is an active swimmer that utilizes all levels of the water column. It will constantly patrol the open water seeking food and establishing its territory. When resting or feeling threatened, it retreats to the middle and lower levels, seeking refuge within the rockwork. Ample swimming space combined with accessible hiding spots is essential 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
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5078
- Bayesian Length-Weight
- a = 0.02291, b = 2.96
- VulnerabilityLow vulnerability (11 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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