Shorefishes of the Greater Caribbean online information system

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Species: Acanthurus tractus, Northern Ocean Surgeonfish

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uniform grey-grown
C concave tips pointed, read edge white

Acanthurus tractus Poey, 1860

Northern Ocean Surgeonfish

Body an elongate, strongly compressed oval; head profile steep; eye high on side of head; mouth small, protrusible, low on head; teeth on jaws fixed, with flattened, notched tips, 14 on top jaw, 16 on lower; gill rakers 18-24; dorsal fin IX, 23-26, not very high, no notch after spines; anal fin III, 21-23; pectoral fin 15-17; pelvic fin I, 5; a single depressible spine fits into a groove on the side of the base of the tail; tail fin edge concave, with pointed tips.

Grey-brown body and fins, pectoral clearish, with yellow cast; short yellow lines radiate from rear of eye in a bluish patch; flank without narrow dark bars; tail with pale bar across base, and a narrow whitish to yellowish rear margin.

Reaches 35 cm; up to at least 32 years.

Found on reefs and in nearby seagrass beds.

Depth range: 0-117 m.

Maine to the S Caribbean.

Note: Acanthurus randalli is a synonym of A. tractus. Acanthurus bahianus (the Ocean surgeonfish) differs in color and genetic makeup from A. tractus, and is the only form found in Brazil and the south Atlantic islands. However, there is genetic evidence indicating that A. bahianus has dispersed to Cuba, Mexico and probably elsewhere in the Greater Caribbean. This puts the specific status of A. tractus in question.

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  • Marine
  • Marine Only
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Rocks
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Submerged vegetation
  • Corals
  • Reef (rock/coral/oyster)
  • Reef and soft bottom
  • Reef associated (reef + edges-water column & soft bottom)
FishBase Habitat
  • Reef Associated
Feeding Group
  • Data
  • Herbivore
  • Data
  • Benthic macroalgae/seagrasses
  • Benthic microalgae
Egg Type
  • Data
  • Pelagic
  • Pelagic larva
Global Endemism
  • All species
  • Greater Caribbean endemic
Regional Endemism
  • Continent
  • Continent + Island (s)
  • Extends North of GC
  • GC endemic
  • Island (s)
  • All species
  • Resident
Climate Zone
  • Equatorial (0-10N, Costa Rica / Venezuela)
  • Subtropical (23-35N, Florida / Carolinas / Bermuda)
  • Temperate (>35N)
  • Tropical (10-23N, Nicaragua / Cuba)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 35
Depth Range Min
  • 0
Depth Range Max
  • 117