Mauritian Anemonefish Breeding Guide
How Amphiprion chrysogaster, the Mauritius-endemic anemonefish, spawns demersal eggs near its host anemone, with the male tending the clutch until the pelagic larvae hatch.
Overview
Amphiprion chrysogaster, the Mauritian anemonefish, is endemic to Mauritius and probably Reunion in the western Indian Ocean. It reaches a maximum length of about 14 cm and lives in symbiosis with the sea anemones Heteractis magnifica, Stichodactyla haddoni and Stichodactyla mertensii. Like all clownfish it is a demersal egg-layer: a pair deposits adhesive eggs on a cleared rock surface beside the host anemone, and the male tends them until hatching. This species is rare in the aquarium trade and breeding reports are scarce, so the account below follows the well-documented Amphiprion reproductive pattern.
Sexing
Clownfish are protandrous sequential hermaphrodites: individuals develop first as males and the dominant individual later becomes female. Within a group there is a strict size-based dominance hierarchy in which the largest, most aggressive fish is the female at the top, followed by the breeding male. Only the dominant male and female reproduce. External sexing is therefore not reliable by colour alone; functional sex is determined by social rank and relative size.
Conditioning
A bonded pair is established by raising several juveniles together and allowing the hierarchy to form, or by pairing a large and a small individual. Conditioning relies on stable reef parameters and frequent feeding; clownfish are omnivores. A host anemone is not strictly required for spawning in captivity but the natural association with Heteractis magnifica, Stichodactyla haddoni or Stichodactyla mertensii reflects the wild setting.
Breeding Setup
- Established male/female pair (largest fish becomes female)
- Mature reef aquarium with stable salinity and temperature 24-26 C
- A flat rock or hard surface near the anemone or shelter for egg deposition
- pH 8.1-8.4, strong biological filtration
Spawning Behavior & Trigger
Spawning in Amphiprion is associated with the lunar cycle and frequently occurs around the full moon. Courtship involves the male chasing and nibbling the female and erecting his dorsal, pelvic and anal fins. The female cleans a rock surface near the anemone and deposits a clutch of up to about a thousand conical eggs roughly 3-4 mm long that adhere to the substrate; the male then fertilises them externally.
Egg & Fry Care
The male performs the parental care, cleaning and guarding the clutch and fanning it with his pectoral fins. Incubation lasts about six to seven days; the eggs start bright orange and progressively darken as the embryos develop visible eyes. After hatching the larvae enter a pelagic open-ocean stage that lasts up to roughly twelve days before they settle, develop adult colouration and seek a host anemone.
Common Challenges
The pelagic larval phase is the principal obstacle: newly hatched larvae are tiny and require dense cultures of rotifers followed by Artemia in a separate, low-flow larval vessel with careful water quality control. The rarity of A. chrysogaster in the trade also limits the availability of unrelated breeding stock. Because detailed captive-breeding data for this endemic species are limited, husbandry is generally extrapolated from better-studied Amphiprion species.