Tomato Clownfish Breeding Guide

How to breed the Tomato Clownfish (Amphiprion frenatus): sex change hierarchy, substrate spawning near the host anemone, male egg tending and rearing fry on rotifers.

Overview

Amphiprion frenatus, the tomato clownfish, can be bred in captivity and, like other anemonefish, lays demersal (substrate-attached) eggs that the male tends. It reaches a maximum length of 14 cm (5.5 in) and is associated with the bubble-tip anemone (Entacmaea quadricolor), and may also use the sebae anemone (Heteractis crispa); a host anemone is helpful but not strictly required to obtain spawns.

Sexing

Clownfish are sequential hermaphrodites that develop as males first and become female on maturity, with a strict size-based dominance hierarchy in which the largest, most aggressive fish is the female. Only two fish in a group, a male and a female, reproduce, through external fertilization. In tomato clownfish the female is larger with blackish sides, while males are considerably smaller and red overall.

Conditioning

Obtaining a compatible pair is the first step; allowing two juveniles to grow up together lets the larger fish become the dominant female. A stable, mature reef-type system with good water quality and frequent feeding conditions the pair toward spawning. Because the fry require live food, rotifer cultures should be prepared in advance.

Spawning Behavior & Trigger

Anemonefish prepare a nest by cleaning a flat patch of rock, typically near the host anemone, where the female deposits eggs for the male to fertilize. Clownfishes lay up to a thousand conical eggs, 3-4 mm long, that stick to the rocky substrate by bundles of short fibres. Courtship involves the male chasing and nibbling the female and erecting his fins.

Egg & Fry Care

The male tends the fertilized eggs, cleaning and guarding them and fanning them with his pectoral fins. Incubation lasts six to seven days, after which pelagic larvae hatch (a stage lasting up to 12 days) before settling. In captivity the fry can be reared on baby brine shrimp and rotifers; offering correctly sized live rotifers from hatching is essential.

Common Challenges

The main difficulty is the short pelagic larval stage that demands a continuous supply of tiny live prey; without prepared rotifer and microalgae cultures, first-feeding larvae starve. Tomato clownfish are among the more aggressive anemonefish, so pairs should not be disturbed once spawning, and tankmates kept to a minimum near the nest.