Eyeline Surgeonfish (species: Acanthurus nigricauda) in Lizard Island Field Guide (Lizard Island Field Guide)
Acanthurus nigricauda
Eyeline Surgeonfish

©Paul Asman: Acanthurus nigricauda at Anchor Bay, Lizard Island.

©Graham Edgar: Acanthurus nigricauda at Cod Hole near Lizard Island.

©Andy Lewis: An adult Eyeline Surgeonfish at Mermaid Cove showing light colouration while feeding over sand. The dark blotch behind the eye and the black streak over the caudal knives are both definitive.
Kingdom Animalia
Phylum Chordata
Class Actinopterygii
Order Perciformes
Family Acanthuridae
Genus Acanthurus
Species Acanthurus nigricauda



Distinguishing features

A medium sized, dark brown fish which appears almost black underwater when viewed from a distance. The crescent shaped tail is distinctive and a white tail ring is often apparent. Distinguish from other Acanthurus species by the rounded head profile, the dark brown pectoral fins with yellow margins, the dark caudal knives with an overlying black streak, and the elongate dark blotch behind the eye.


  • Up to 35 cm (Standard length)

Depth range

  • Depth range data is not yet available.


Similar taxa


©Atlas of Living Australia: Australian distribution

Distribution and habitat preferences

Areas of turf algae and coral rubble on sheltered lagoonal reef flats and slopes, and sandy substrata close to reef edges.

Found in most reef habitats around the island, usually near areas of sand along reef margins.


The Eyeline surgeonfish is a roving detritivore, moving around the reef usually singly or in small groups, and feeding on the organic detritus that accumulates on sandy and turf algal covered substrata. The surgeonfish are a very long lived group of fishes - after settlement to the reef, juveniles grow quickly and reach 80% of their maximum size in about 3 years, and then grow very slowly thereafter. Many of them live from 30-50years. They spawn in groups during the warmer months, when fast running tidal currents coincide with dawn and dusk.

Web resources


  • unspecified - There are a pair of poisonous bony knives at the base of the tail, which can be used to inflict a painful stabbing wound if the fish is handled.


  • Brandl, S.J. and D.R. Bellwood (2013). Morphology, sociality, and ecology: can morphology predict pairing behavior in coral reef fishes? Coral Reefs, 32: 835-836. LIRS catalog number 1718.
  • Brandl, S.J. and D.R. Bellwood (2014). Individual-based analyses reveal limited functional overlap in a coral reef fish community, Journal of Animal Ecology, 83: 661-670. LIRS catalog number 2063.
  • Brandl, S.J., W.D. Robbins and D.R. Bellwood (2015). Exploring the nature of ecological specialization in a coral reef fish community: morphology, diet and foraging microhabitat use, Proceedings of the Royal Society B, 282: 20151147, doi.org/10.1098/rspb.2015.1147. LIRS catalog number 1908.
  • View all references