Allen's Damsel (Pomacentrus alleni) Breeding Guide

Pomacentrus alleni is an oviparous damselfish that lays demersal eggs adhering to the substrate, with males guarding and aerating the clutch. Larval rearing at home is not established.

Overview

Pomacentrus alleni Burgess, 1981 (Andaman damsel in scientific literature) is a small damselfish from the Eastern Indian Ocean, recorded around the Similan Islands of Thailand and Indonesia, and reaching about 6 cm total length. FishBase records it as oviparous with distinct pairing during breeding, following the demersal-spawning pattern of the family Pomacentridae in which males tend eggs laid on the substrate.

Sexing

No reliable sexual dimorphism or external sexing character is documented for P. alleni in the consulted sources. As with most damselfishes, the most practical indication of sex emerges during reproduction, when the nest-tending, more aggressive individual is the male; the species is otherwise broadly monomorphic.

Conditioning

A species-specific conditioning protocol is not documented. P. alleni is a low-trophic omnivore (trophic level about 2.7) that in the wild occupies rubble and dead-reef habitat on outer slopes; a varied marine diet and stable warm conditions (the species occurs at around 28–29 °C in the wild) support condition. Aquarium parameters within the recorded reef ranges (temperature about 24–26 °C, pH 8.1–8.4) are appropriate.

Breeding Setup

Provide open rock or rubble that lets a male establish and clean a defensible nest patch, mirroring the wild rubble and dead-reef habitat. Following the family pattern, the male clears an area of algae and invertebrates before spawning. Because Pomacentrus damsels are territorial, generous space and structure to break sightlines reduce aggression around the nest.

Spawning Behavior & Trigger

Specific spawning triggers for P. alleni are not documented. Across Pomacentridae, spawning is preceded by ritualised courtship; the female then lays a string of sticky eggs attached to the substrate which the male fertilises 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 development. At family level, eggs hatch over roughly two to seven days into transparent larvae about 2–4 mm long that disperse into a pelagic phase lasting from about a week to over a month. This pelagic larval stage is the main barrier to captive reproduction.