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EveryFish
Achilles Tang ( Acanthurus achilles )

Achilles tang

A black reef fish with an orange tail spot.

Photo: cello caruso-turiello, CC BY 4.0, via Wikimedia Commons

The Achilles tang is a marine ray-finned fish found in Pacific reefs. It features a dark body with a distinct orange patch and sharp spines. First described in 1803, it grazes on algae and lives in monogamous pairs.

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  • Reaches a maximum length of 24 cm
  • Has a distinct orange blotch on a black body
  • Grazes on benthic algae in clear reef waters
  • Forms monogamous pairs in the wild
  • Can hybridize with Acanthurus nigricans

What it is

This marine ray-finned fish belongs to the surgeonfish family. It has an elongated oval body with a steep head profile. The mouth sits low on the head and contains serrated teeth. A single mobile spine lies on each side of the tail base. The body is bluish-black with an irregular orange blotch near the rear. A white bar marks the gill cover, and the tail fin is mostly orange with a white edge. Adults grow up to 24 cm long.

Where it lives

The species inhabits various reefs across the Pacific Ocean. Its range extends to the islands of Hawaii and Pitcairn. It appears less frequently in the Mariana Islands. Some populations exist on reefs in southern Mexico and Guatemala. These fish prefer clear waters located on the seaward side of coral reefs. They are benthopelagic, meaning they live near the bottom but also swim in open water above the reef structure.

How it lives

Achilles tangs are herbivores that graze primarily on benthic algae. They maintain specific territories within their reef habitat. This species exhibits monogamous behaviour, forming pair bonds. They use their serrated teeth to scrape algae from surfaces. The mobile spines on their caudal peduncle can fold into slits for protection. They share their environment with other reef species but defend their feeding areas.

Breeding and life cycle

These fish are monogamous, pairing with a single mate. Specific details regarding spawning seasons or egg development are not provided in the available data. Their reproductive cycle aligns with their territorial nature. Hybrids have been recorded with the congener Acanthurus nigricans, indicating some genetic overlap with related species in shared habitats.

Achilles 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

The Achilles tang is kept in aquariums due to its striking colouration. Care sheets exist for hobbyists interested in maintaining this species. Its common name references the mythical hero Achilles, likely alluding to the sharp bony plates on its tail. It is not typically cited as a food fish in the provided information. The species is valued for its visual appeal in marine tank setups.

Photo of Achilles × Whitecheek Tang uploaded from iNaturalist .
Photo of Achilles × Whitecheek Tang uploaded from iNaturalist .. Photo: (c) jeyre, some rights reserved (CC BY), CC BY 4.0, via Wikimedia Commons
"Acanthurus achilles" at the Aquarium of Monaco
"Acanthurus achilles" at the Aquarium of Monaco. Photo: Hectonichus, CC BY-SA 3.0, via Wikimedia Commons

Questions people ask about Achilles tang

What does an Achilles tang eat?

This fish is herbivorous. It grazes largely on benthic algae found on reef surfaces. Its serrated teeth are adapted for scraping this plant material from rocks and coral structures in its territory.

Where is the Achilles tang found?

It lives in various reefs across the Pacific Ocean. Common locations include Hawaii and Pitcairn Islands. It is also found less commonly in the Mariana Islands, southern Mexico, and Guatemala.

Why is it called the Achilles tang?

The name likely refers to the mythical hero Achilles. It alludes to the sharp bony plates on the caudal peduncle, resembling the hero's vulnerability or strength. The specific name was chosen by George Shaw in 1803.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Acanthurus achilles", 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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