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EveryFish
Blue surgeonfish ( Acanthurus leucosternon ), Zanzibar, Tanzania

Powder blue tang

A bright blue reef fish from the Indian Ocean.

Photo: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons

The powder blue tang is a marine fish found in the Indian Ocean. It lives on shallow reefs and eats algae. Edward Turner Bennett described it in 1833. The species is popular in home aquariums but requires careful maintenance.

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  • Reaches an average length of 23 cm
  • Found in shallow reefs of the Indian Ocean
  • Has a sharp spine at the base of the tail
  • Popular in marine aquariums but hard to keep
  • Feeds primarily on benthic algae

What it is

This marine ray-finned fish belongs to the surgeonfish family. It has an oval body that is flattened from side to side. Adults reach about 23 cm in length. The head is black, while the sides are a vivid blue. The chest, throat, mouth, anal fin and pelvic fins are white. The dorsal fin and tail base are yellow. Pectoral fins are clear with yellow hints. A sharp spine at the tail base acts as a defensive scalpel. The colour intensity indicates health status.

Where it lives

The species lives in tropical waters of the Indian Ocean. Its type locality is Sri Lanka. It inhabits shallow and clear coastal areas always linked to reefs. These fish prefer flat topped reefs and zones along seaward slopes. They do not migrate far from these reef structures.

How it lives

These fish are active during the day. They are herbivores that feed mainly on benthic algae. The small pointed mouth has tiny sharp teeth for scraping food from narrow spaces. They are solitary and territorial. Aggression towards other surgeonfish is common. They may form shoals when food is abundant but compete individually when it is scarce. The tail spine serves as a weapon against threats.

Powder blue tang
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

This species is rarely caught for food. It is sold frequently for the marine aquarium trade. Care is moderately difficult compared to other tangs. It is less popular than the regal or yellow tang. The fish is prone to a parasite called Cryptocaryon irritans. It is safe for reef tanks but conflicts with other Acanthurus species. Keepers value its bright appearance despite the care challenges.

Fish with black background.
Fish with black background.. Photo: Ltz Raptor, CC BY-SA 3.0, via Wikimedia Commons
Powder Blue Tang ( Acanthurus leucosternon ) in Mozambique
Powder Blue Tang ( Acanthurus leucosternon ) in Mozambique. Photo: Georgina Jones, CC BY-SA 4.0, via Wikimedia Commons
Surgeonfish (Acanthurus leucosternon), Maldives
Surgeonfish (Acanthurus leucosternon), Maldives. Photo: Uxbona, CC BY 3.0, via Wikimedia Commons

Questions people ask about Powder blue tang

Where does the powder blue tang live?

It is found in the tropical waters of the Indian Ocean. It prefers shallow, clear coastal waters associated with reefs, specifically flat top reefs and seaward slopes.

What does this fish eat?

It is herbivorous and eats mostly benthic algae. Its small, beak-like mouth with sharp teeth allows it to reach into narrow spaces to scrape food from surfaces.

Is it aggressive towards other fish?

Yes, it is solitary and territorial. It shows aggression toward other surgeonfish, especially those in the same genus. It is best kept with compatible species outside this group.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Acanthurus leucosternon", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

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Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

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