Shorefishes of the Eastern Pacific online information system

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Species: Gobiomorus maculatus, Bigscale sleeper, Pacific sleeper

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head elongate, conical
eye oval
mouth large, lower jaw projects
gill opening to under end mouth
~ 50-60 rough lateral scales



Gobiomorus maculatus (Günther, 1859)

Pacific sleeper, Bigscale sleeper

Body elongate, cylindrical, narrowing to rear; head elongate, conical in profile, depressed above;  eye a longitudinal oval; mouth large, lower jaw projecting; teeth small conical, in several rows on jaws; teeth on front of roof of mouth; gill openings extend forward nearly to the level of the angles of the mouth, separated from each other by a very narrow isthmus; gill membranes with 6 rays; dorsal fins VI weak spines + I, 9, fins well separated, base of 2nd dorsal < distance from the end of that base to tail fin; anal fin I, 9-10; pectoral 15-16, fin rounded;pelvic fins I, 5, long, completely and widely separated; scales rough on body, smooth on head, medium sized, 51-57 in lateral series, on body, forehead, cheeks and operculum; no lateral line.

Adult with head and body dark mottled brown; paler below; both dorsal and tail fins clear with rows of small dark spots on membranes; pectoral, pelvic and anal fins clear, pectoral with a dark band at its base. Juvenile with a dark stripe along the midside and 3 bars radiating from the eye (to middle and to rear of mouth, and to the upper corner of the operculum).

Reaches 35cm.

Habitat: usually found in freshwater, but enter brackish tidal areas.

Depth: 0-5 m.

The tip of Baja California and the mouth of the Gulf of California to northern Peru, as well as the Galapagos and Cocos.

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  • Brackish
  • Non Marine
  • Freshwater
  • Inshore Only
  • Inshore
Water Column Position
  • Bottom only
  • Bottom
  • Estuary
  • Freshwater
  • Mangrove
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Soft bottom only
FishBase Habitat
  • Demersal
Feeding Group
  • Data
  • Carnivore
  • No Data
  • Bony fishes
Egg Type
  • No data
  • Pelagic larva
  • Benthic
Global Endemism
  • East Pacific endemic
  • All species
  • Tropical Eastern Pacific (TEP) endemic
Regional Endemism
  • Continent + Island (s)
  • Continent
  • All species
  • Island (s)
  • TEP endemic
  • Resident
Climate Zone
  • Northern Subtropical (Cortez Province + Sinaloan Gap)
  • Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo)
  • South Temperate (Peruvian Province )
  • Northern Tropical (Mexican Province to Nicaragua + Revillagigedos)
IUCN Red List
  • Listed
  • Least concern
  • Not listed
Length Max
  • 35
Depth Range Min
  • 0
Depth Range Max
  • 5