Yellowfin Grouper
Mycteroperca  venenosa
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
Co, R to 100 Pisc I PGH
Adult: Rectangular blotches over a light background and can be black, grey, brown, olive-green or red. Usually the morph is associated with dpth, with deep-water reddish form and shallow-water greenish form.
Outer 1/3 of pectoral fin yellow. Ends of rectangular body blotches are rounded (in the similar Black Groupre, M. bonaci, there are squarer). Small spots on lower body and tail. Tail has thin, irregular dark margin. Can pale the blothched pattern to become indistinct, showing only spots.
Males are somewhat bigger then the females and  identified by distinctive yellow marks on both jaws, females being red.
Juvenile: More widely spaced and rounder spots on body.

Adults are solitary and  found on rocky and coral reefs at depths from 2 - 137m, juveniles occur in shallow turtle grass beds.  Feeds mainly on fishes (mostly on coral reef species) and squids. The colour of their bodies is exceptionally changeable due to pigment-containing and light-reflectingcells (chromatophores) to adapt to their environment. When the fish is hiding its colour is completely dark with no yellow patch, and males are white-headed when attracting females to mate.
Life Cycle:
Oviparous. Length at maturity ~50cm. A protogynous hermaphrodite, females change sex to males at about 8-9 years old and 65cm long although sex reversal has been observed.  This species lives up to 15 years.
These fish gather together at a particular area and time for mating purposes, determined by the amount of yellowfin groupers in that particular area. The cluster can range from 2-4 individuals, up to hundreds for a large group. The males have a white head and display to females by placing themselves beside them and rotating 90 degrees over the females, simultaneously jerking their body. Females are signalled to gather by noises made by the males.
Yellowfin Grouper
(C) Rod Griffin/  EDF
Yellowfin Grouper
Yellowfin Grouper Juvenile