Genicanthus lamarck (Lamarck's Angel) Breeding Guide
Genicanthus lamarck is a reef-safe, sexually dichromatic swallowtail angel that pair-spawns pelagic eggs. Some Genicanthus are captive-bred, but home rearing of larvae is impractical.
Overview
Genicanthus lamarck is a swallowtail angelfish of the Indo-West Pacific, from the Malayan region east to Vanuatu, north to southern Japan and south to the Great Barrier Reef. It reaches about 25 cm at depths of roughly 10 to 50 m, feeding on plankton in midwater. Unlike most angelfish it ignores corals and sessile invertebrates, making the genus reef-safe. Genicanthus are regarded as the most breedable angels, though captive offspring remain a specialist achievement.
Sexing
Genicanthus is the only sexually dichromatic angelfish genus, so the sexes are easily told apart. In G. lamarck males show a yellow crown patch, black pelvic fins and elongated caudal lobes, while females have white pectoral fins and black caudal lobes. It is a protogynous hermaphrodite: if the male in a harem disappears, the dominant female changes sex to male.
Spawning Behavior & Trigger
In the wild G. lamarck lives in small harems of a dominant male with two to six females, forming feeding aggregations in midwater. Swallowtail angels are pair-spawners: as in other pomacanthids, courtship intensifies toward dusk, when a female rises into the water column with the male and releases buoyant pelagic eggs at the peak of the ascent.
Egg & Fry Care
Genicanthus produce extremely small pelagic eggs that hatch into equally minute prolarvae. Standard rotifers are too large for the first-feeding mouth, so successful rearing in related species has relied on cultured copepods and other tiny live prey. There is no parental care; raising the larvae, rather than achieving spawning, is the central difficulty.
Common Challenges
- Pelagic eggs disperse on release and cannot be collected from a display.
- Prolarvae are too small for rotifers and need cultured copepods.
- A breeding pair needs a very large reef system, given the adult size.
- No captive rearing of this particular species has been documented.