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Species: Stegastes diencaeus, Longfin Damselfish

All Families:   All Genera:   All Species:

deep oval
D & A long, rounded; C large, rounded lobe
grey to black; A edge blue line
Juv: yellow + 2 blue lines on head, D base - large ocellus

Stegastes diencaeus (Jordan & Rutter, 1897)

Longfin Damselfish

Body deeply oval, compressed; 1 pair of nostrils; margin of preopercle serrated; margin of bone under eye serrated, without notch between it and the bone before it; mouth small, protrusible, opens at front; teeth in single row, long and close-set incisors; 10-11 lower gill rakers; a single continuous dorsal fin, XII, 14-17; anal fin II, 13; dorsal and anal fins long and rounded, reaching past base of tail fin; pectoral rays 19-21; no projecting short spines at upper and lower base of tail fin; caudal fin bluntly forked, lobes large and rounded; scales are moderately large and rough; body scaled, head largely scaled (snout scaled to nostrils), as are the basal parts of the median fins; lateral line incomplete, ends under end of dorsal fin base; lateral-line scales 19-20.

Adult: blackish to grey; snout, upper edge of eye-ball and nape with yellowish-brown cast; outer margin of anal fin with thin bright blue line. Juvenile: bright yellow body and fins; snout, nape and top of back grey-brown; 2 dotted blue lines along snout, top of head and upper back; a large black and blue ocellus at base of rear dorsal fin spines and upper body.

Size 12.5 cm.

Occurs on reefs, usually in sheltered areas.

Depth: about 0-45 m.

North Carolina to the S Caribbean.

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  • Marine
  • Marine Only
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Reef only
  • Rocks
  • Corals
  • Reef (rock/coral/oyster)
  • Reef associated (reef + edges-water column & soft bottom)
FishBase Habitat
  • Reef Associated
Feeding Group
  • Data
  • Omnivore
  • Data
  • Benthic microalgae
  • Mobile benthic crustacea (shrimps/crabs)
Egg Type
  • Benthic
  • Data
  • No pelagic phase
  • Pelagic larva
Global Endemism
  • All species
  • Greater Caribbean endemic
  • West Atlantic Endemic
Regional Endemism
  • Continent
  • Continent + Island (s)
  • Continental primarily
  • GC endemic
  • 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
  • 12.5
Depth Range Min
  • 0
Depth Range Max
  • 45