Cocoa Damselfish (Stegastes variabilis) Breeding Guide

Stegastes variabilis is a territorial Western Atlantic damselfish that lays demersal eggs on the substrate, guarded and aerated by the male. Pelagic larvae make home rearing difficult.

Overview

Stegastes variabilis, the cocoa damselfish, is a Western Atlantic species recorded from the Caribbean (described from Cuban specimens) and Brazil, reaching about 12.5 cm total length. Adults are dusky brown while juveniles are bright blue with a yellow back, and the species is aggressively territorial. FishBase records it as oviparous with distinct pairing during breeding and notes aggression during breeding periods.

Sexing

No reliable external sexing character is documented for S. variabilis in the consulted sources, and adult colour differences are age-related rather than sex-linked. As in other Stegastes, the nest-defending, more aggressive individual during reproduction is the male.

Conditioning

A species-specific conditioning protocol is not documented. Adults consume mainly benthic algae supplemented with sponges, ascidians and anemones, while juveniles feed on invertebrates such as harpacticoid copepods; a varied marine diet with a grazing surface supports condition. Maintain stable reef parameters within the recorded ranges (temperature about 24–26 °C, pH 8.1–8.4).

Breeding Setup

Because the species is aggressively territorial, a male needs ample defensible rock to establish a territory and nest. Following the family pattern, the male clears a nest area on the substrate. The species' aggression makes it unsuitable for crowded community systems during reproduction; provide space and sightline breaks.

Spawning Behavior & Trigger

Specific spawning triggers for S. variabilis are not documented. In Pomacentridae, ritualised courtship precedes spawning; the female lays a string of sticky eggs attached to the substrate within the male's territory and the male fertilises them externally. FishBase confirms the eggs are demersal and adhere to the substrate and that males guard and aerate them.

Egg & Fry Care

The male guards and aerates the clutch through incubation. At family level, eggs hatch over about two to seven days into transparent larvae roughly 2–4 mm long that disperse into a pelagic phase. This planktonic stage is the principal barrier to captive reproduction.