Saddleback Anemonefish (Amphiprion polymnus) Breeding Guide

How to breed the captive-bred saddleback anemonefish Amphiprion polymnus: pairing, demersal eggs near a host anemone, male tending and rearing the pelagic larvae.

Overview

Amphiprion polymnus is a demersal egg-layer that is regularly captive-bred. FishBase records it as oviparous with distinct pairing, the eggs demersal and adhering to the substrate, and the male guarding and aerating them. It is a protandrous hermaphrodite with a recorded length at sex change of about 9.2 cm, so the largest fish becomes the female and the breeding male can change sex if she is lost.

Sexing

Sex is determined by size and social rank rather than colour. In a pair the female is the larger fish and the breeding male is smaller; FishBase gives a length at sex change near 9.2 cm. A lone fish functions as a male and will become female when paired with a smaller one, so pairing two juveniles and letting the dominant one mature into the female is the most reliable route to a breeding pair.

Conditioning

Condition the pair on frequent, varied marine feedings and stable water. The species lives in silty lagoons and harbours and almost always associates with the anemones Heteractis crispa and Stichodactyla haddoni; offering a host anemone, particularly S. haddoni, lowers stress and encourages a steady spawning routine.

Breeding Setup

Provide the pair their own territory with a flat hard surface near the host anemone, where the female deposits eggs on a cleaned patch close to the anemone. Keep stable reef parameters; the record lists about 24-26 degrees Celsius and pH 8.1-8.4, and FishBase gives a wild depth of roughly 2-30 m. The pair clean and defend the nest before spawning.

Spawning Behavior & Trigger

The female lays a clutch of conical eggs (clownfish lay up to about a thousand, each 3-4 mm long) which the male fertilises and then tends, cleaning, guarding and fanning them with his pectoral fins. The eggs start bright orange and darken as the embryos and eyes develop. Settled, well-fed pairs spawn on a regular repeating cycle near the host anemone.

Egg & Fry Care

Incubation lasts six to seven days and the larvae hatch at night. The newly hatched larvae pass through a pelagic stage of up to about 12 days before settling, during which they must be reared separately on appropriately small first foods such as rotifers, advancing to larger live foods as they grow. They are far too small to take adult food at hatching.

Common Challenges

The pelagic larval phase is the principal hurdle: the minute larvae require clean rearing water and correctly sized live first foods or mortality is high. The species is semi-aggressive, so a poorly matched pair may fight. Transferring the egg-bearing surface or the freshly hatched larvae to a dedicated rearing tank protects them from predation in the main display.