Achilles tang (Acanthurus achilles) care guide

Group
Marine fish
Family
Acanthuridae (surgeonfishes and tangs)
Origin
Hawaii and the South Pacific (per the list)
Water
saltwater
Maximum size
28 cm
Temperature
24–27°C
pH
8.1–8.4
Hardness
Salinity SG 1.023–1.026
Minimum tank
700 litres
Care level
expert
Temperament
semi_aggressive
Reef safe
yes

Care

Tank and decor: an active, open-water swimmer that needs a long tank with plenty of swimming room, live rock for grazing and strong, well-oxygenated flow. Minimum tank: about 700 litres (an estimate based on its 28 cm adult size and active swimming; the list says a six-foot or larger tank). Water: our sources give no species-specific figures, so the values here are general marine aquarium guidance, not species-specific: 24–27 °C, pH 8.1–8.4 and specific gravity 1.023–1.026. Keep nitrate low and the water well oxygenated. Behaviour and identification: a black tang with an orange teardrop-shaped patch at the tail base. The list describes it as passive-aggressive, says it needs strong flow and a tank of six feet or more, and warns it is prone to marine whitespot (Cryptocaryon irritans), so quarantine is essential. The list gives a maximum size of 28 cm. Safety: like all surgeonfishes it has a sharp, scalpel-like spine on each side of the tail base that can cut hands and get caught in nets. Use a container to move it. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies). Checked October 2026.

Diet

Herbivore. Offer marine algae every day: dried nori or seaweed sheets on a clip, spirulina- and seaweed-based flakes and pellets, and frozen herbivore foods, with occasional mysis. Live rock with algae growth helps. Several feeds a day suit it best.

Breeding

Our sources for this page do not describe breeding. Tangs spawn in open water and have long-lived planktonic larvae, and almost all aquarium tangs are wild-caught.

Compatibility and tank mates

Reef safe: it leaves corals and invertebrates alone, though it grazes algae. It can be territorial towards other tangs, especially similar-looking ones, so add tangs at the same time in a large tank, or keep one per tank.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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