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Species: Bathygobius mystacium, Island Frillfin, Island Frillfin Goby

All Families:   All Genera:   All Species:

nape scales - > well before preopercle edge
body: 3 saddles above, I row 6 large square blotches below
D: 1-3 stripes, edge yellow
C base: 2 dark spots
top jaw short
pectoral 18-21
lateral scales 35 (33-36)

Bathygobius mystacium Ginsburg, 1947

Island Frillfin, Island Frillfin Goby

Body robust; head broad, depressed, with pores; snout bluntly rounded; eyes large, close together; mouth moderate sized, relatively horizontal, top jaw 9.2-11 (rarely to 11.7) % of SL; tongue is notched; jaw teeth in bands, without canines; teeth in upper jaw in a narrow band, outermost teeth enlarged, without canines; gill membranes broadly joined to body under throat, with 5 rays; dorsal fin VI (none elongate) + I, 8-9; length of 2nd dorsal base > distance from 2nd dorsal base to tail fin; anal I, 7-8; pectoral 18-21, upper 4 (3-5) rays free, silky threads; pelvic fins I, 5, united to form a disc; tail fin rounded; scales large, rough, 35 (33-36) in lateral series, present on midline of nape to well before a line through rear edge of preopercle; no scales on cheek or operculum; no lateral line.

Grayish brown; upper half of body with 3 distinct dark saddles; lower body with a row of 6-7 irregular to squarish, dark, pupil-to eye-sized blotches; 1st dorsal fin with 1-3 dark spotted stripes and a yellow outer edge, sometimes uniform dark in large fish; a large dark blotch on lower 2/3 of tail fin base that joins a small blotch above it on tail base, outer part of tail fin with 3-4 narrow dark bars; yellowish scale edges form zigzag yellow lines along body.

Reaches 7 cm.

Depth range: 0-3 m.

Habitat: shallow sand/rock habitats on the seaward sides of islands.

Florida to Brazil

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  • Marine
  • Marine Only
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Bottom only
  • Rocks
  • Sand & gravel
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Reef (rock/coral/oyster)
  • Reef and soft bottom
  • Reef associated (reef + edges-water column & soft bottom)
FishBase Habitat
  • Demersal
  • Reef Associated
Feeding Group
  • Carnivore
  • Data
  • Data
  • Insects
  • Mobile benthic crustacea (shrimps/crabs)
Egg Type
  • Benthic
  • Data
  • Pelagic larva
Global Endemism
  • All species
  • Greater Caribbean non-endemic
  • West Atlantic Endemic
Regional Endemism
  • Also in Brazil
  • Continent
  • Continent + Island (s)
  • Extends South of GC
  • GC non-endemic
  • Insular primarily
  • Island (s)
  • All species
  • Resident
Climate Zone
  • Equatorial (0-10N, Costa Rica / Venezuela)
  • Subtropical (23-35N, Florida / Carolinas / Bermuda)
  • Tropical (10-23N, Nicaragua / Cuba)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 7
Depth Range Min
  • 0
Depth Range Max
  • 3