Bicolor Damselfish
Stegastes partitus
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
Co/ R 10 Pla, Veg Ter F
Adult: Body relatively elongate, robust, compressed.  Dorsal and anal fins short, not reaching base of tail fin, having soft lobes with angular tips. Tail bluntly forked, lobes with angular tips. 
Front half of body usually black.
Adult colouration is highly variable and with intergrading patterns e.g.: 1. Black, soft dorsal fin, with tail base and sometimes tail are white. 2. Upper head and back and front half of dorsal fin blackish; lower head, belly, flank and pelvics fins orangish: rest of body, anal and tail fins white. 3 Head and body white: tail base and fin and margins of dorsal and anal fins blackish; pectoral yellowish.

Juveniles:  Like adult

Inhabits shallow coral reefs and isolated patch reefs in deeper water up to 25m. Algal feeders, which unlike other Stegates also feed on plankton (as per Chromis spp) This species is aggressively territorial around a small area, however may form groups with up to 20
other individuals. In this case there will be a dominant male at the head of the group. Should the alpha damselfish be challenged by a younger male and lose, the alpha position is passed onto the winner therefore dominance is dependent on the ability of the damselfish.

Life Cycle:
Adults spawn demersally following a unimodal lunar cycle with year-round reproduction and seasonal reproductive peaks from April to November. Produce a "3 pulse chirp" sound during courtship. Males provide parental care to the eggs; however, after hatching (~3.5 days), larvae enter the pelagic environment and the pelagic larval duration ranges between 24 and 40 days. After settlement, the adults are sedentary, defending small feeding territories indefinitely. The thirty days of larval development allows for the potential for long-distance dispersal. 
Bicolor Damselfish
Bicolor Damselfish
(C) JE Randall
Bicolor Damselfish
(C) Dr P Ryan/ RyanPhotographic