Shorefishes of the Eastern Pacific online information system

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Species: Opistognathus rhomaleus, Giant jawfish

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head & back: small dark spots
juvenile: 6 dark bars + edge operculum dark
lips: inner papillae
inside mouth plain
gill rakers 28-33

Opistognathus rhomaleus Jordan & Gilbert, 1881

Giant jawfish

Elongate, compressed, tapering body; large bulbous head; eye large, high; a short simple cirrus at front nostril; rear end of top jaw straight, without fringe at rear, extending well beyond eye, about 59% of head length, but not reaching margin of preopercle, same size in males and females; lips with inner papillae; no broad flap under opercle; 2-4 teeth at front of roof of mouth;  gill rakers 28-33; dorsal rays XI, 12-14; anal rays II, 13; pectoral rays 20-21; tail rounded, much shorter than head; lateral line on front half of body only, high; scales small, smooth, none on head, body with 100-105 oblique scale rows.

Light grey with numerous small black spots on head and upper back; sides of adult devoid of markings or with ~5 faint dark bars on upper body; dorsal fin with a series of 5-6 black blotches along its base corresponding to the body bars; juvenile with 5-6 large,  dark brown blotches on flank; dorsal fin with whitish base and 6 black spots corresponding to the body blotches; inside mouth without obvious color pattern.

Size: reaches 51 cm.

Inhabits sand-rubble bottoms, often caught by anglers and trawlers.

Depth: 3-70 m.

Central Baja and the Gulf of California to W Panama, and Revillagigedo Islands.

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  • Marine
  • Marine Only
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Bottom only
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Reef associated (reef + edges-water column & soft bottom)
  • Sand & gravel
  • Soft bottom only
FishBase Habitat
  • Demersal
Feeding Group
  • Carnivore
  • No Data
  • Mobile benthic gastropods/bivalves
  • Mobile benthic crustacea (shrimps/crabs)
  • No Data
  • Bony fishes
Egg Type
  • Brooded
  • No data
  • Pelagic larva
Global Endemism
  • Tropical Eastern Pacific (TEP) endemic
  • East Pacific endemic
  • All species
Regional Endemism
  • Island (s)
  • Continent
  • All species
  • TEP endemic
  • Continent + Island (s)
  • Resident
Climate Zone
  • Northern Subtropical (Cortez Province + Sinaloan Gap)
  • North Temperate (Californian Province &/or Northern Gulf of California)
  • Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo)
  • Northern Tropical (Mexican Province to Nicaragua + Revillagigedos)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 51
Depth Range Min
  • 3
Depth Range Max
  • 70