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Species: Butis koilomatodon, Mud Sleeper

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head rounded, scaled
serrated bony ridge over eye
body: 3 double bars, 1 & 2 - > dark blotch on D1 & 2
C base dark bar
lower pectoral base - black blotch
body scales rough
lateral scales 25-33

Butis koilomatodon (Bleeker, 1849)

Mud Sleeper

Elongate; head and snout rounded, snout short; mouth short, oblique, reaches under front edge of eye; serrated bony ridge over each eye; front nostril a short tube; lower edge of gill opening extends forward to below eye; gill rakers 4-5 upper, 6-8 lower; no downpointing spine on preopercle; gill membranes broadly joined to throat, with 6 rays; dorsal fin VI + I, 8, base of 2nd dorsal < distance from the end of that base to tail fin; anal fin I, 7-8; pectoral fin 21-22, rays branched; pelvic fins I, 5, completely separate; segmented tail fin rays 17; body scales rough; lateral scales 25-28; top of head, cheeks and operculum scaled, no enlarged scale between eyes; no lateral line.

Head and body brown, with darker scale edges; several dark bars radiating down from eye; body with a pair of oblique dark bars under each dorsal fin, which extend onto those fins, forming a dark blotch on front half of each fin; another pair of dark bars on tail base; tail fin base with dark bar; second dorsal and tail fins with rows of pale spots; lower base of pectoral fin with a conspicuous dark blotch; anal and pelvic fins dark; female and juvenile with stronger body bars.

Reaches 10.7 cm.

Lives in estuaries, enters freshwater and marine conditions.

Depth range: 0-7 m?

Natural range is the Indo-west Pacific; Intoduced to the E&W Atlantic: Panama to Brazil.

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  • Brackish
  • Freshwater
  • Marine
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Bottom only
  • Sand & gravel
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Estuary
  • Freshwater
  • Mangrove
  • Mud
FishBase Habitat
  • Demersal
Feeding Group
  • Carnivore
  • Data
  • Data
  • Bony fishes
  • Mobile benthic crustacea (shrimps/crabs)
Egg Type
  • Benthic
  • Data
  • Pelagic larva
Global Endemism
  • All species
  • Exotic (Introduced)
  • Greater Caribbean non-endemic
Regional Endemism
  • Also in Brazil
  • Continent
  • Continent only
  • Exotic (Introduced)
  • Extends South of GC
  • GC non-endemic
  • All species
  • Resident
Climate Zone
  • Equatorial (0-10N, Costa Rica / Venezuela)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 10.7
Depth Range Min
  • 0
Depth Range Max
  • 7