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Species: Polydactylus octonemus, Atlantic Threadfin

All Families:   All Genera:   All Species:

gill rakers 34-38
pectoral black, 8 free rays
LL 54-64, 6 LL above, 11 below

Polydactylus octonemus (Girard, 1858)

Atlantic Threadfin

Elongate, compressed; snout short, conical, translucid, overhangs mouth; eyes large, longer than snout, with fatty cover, at front of head; mouth moderate, below, with bottom lip extending to front, but no top lip; tooth bands of top jaw touching in center; preopercle serrated; gill rakers 34-38 (mean 36); two well separated dorsal fins, VIII + I, 11-13; anal fin base short, III, 12-14; pectoral fin low on side 15-16 rays on main part, plus lower portion consisting of 8 (rarely 9) free filaments; horizontal length of total fin base shorter than upper jaw; pelvics well behind pectoral base, under 1st dorsal; tail strongly forked; scales rough; lateral line pored scales 56-64; 6 (6-7) scales above lateral line, 11 (10-12) below; lateral line extends onto tail fin.

Head and body yellow to bronze, whitish below; snout translucent; dorsal and anal yellowish, with black tips; pectorals black, with translucent filaments.

Size: grows to 33 cm.

Inhabits sand-mud bottoms of bays, estuaries, and river mouths, also occurs along sandy beaches.

Depth: 1-66 m.

New York to the Gulf of Mexico.

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  • Brackish
  • Marine
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Sand & gravel
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Soft bottom only
  • Beach
  • Estuary
  • Mud
FishBase Habitat
  • Demersal
Feeding Group
  • Carnivore
  • Data
  • Planktivore
  • Data
  • Zooplankton
  • Bony fishes
  • Mobile benthic crustacea (shrimps/crabs)
  • Mobile benthic worms
Egg Type
  • Data
  • Pelagic
  • Pelagic larva
Global Endemism
  • All species
  • Greater Caribbean endemic
  • West Atlantic Endemic
Regional Endemism
  • Continent
  • Continent only
  • GC endemic
  • All species
  • Resident
Climate Zone
  • Subtropical (23-35N, Florida / Carolinas / Bermuda)
  • Tropical (10-23N, Nicaragua / Cuba)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 33
Depth Range Min
  • 1
Depth Range Max
  • 66