Description:

Acanthochromis polyacanthus is a species of fish commonly known as the Spiny Chromis or Spiny Puller. It belongs to the family Pomacentridae, which includes damselfishes and clownfish.

It is notable for a unique life history trait that distinguishes it from almost all other coral reef fish.

Key Facts

Common Name(s): Spiny Chromis, Spiny Puller, Orange Line Chromis (juvenile)
Scientific Name: Acanthochromis polyacanthus
Family: Pomacentridae (Damselfish)
Max Size: Up to 1416 cm (about 5.56.3 inches)
Distribution: Western Pacific Ocean, including Indonesia, the Philippines, northern Australia (Great Barrier Reef), and Melanesia.
Habitat : Coral reefs, lagoons, and seaward slopes, typically found between 420 meters deep.
Diet: Omnivorous (planktonivorous and algivorous in the wild).Unique Reproductive Strategy
The most significant aspect of A. polyacanthus is its life cycle, which is extremely rare among marine reef fish:

No Pelagic Larval Stage: Unlike nearly all other coral reef fish, the Spiny Chromis does not have a planktonic larval stage where eggs and larvae drift in the open ocean currents.

Extended Parental Care: It exhibits biparental care where both parents guard their eggs (laid on the reef) and continue to guard the hatched juveniles for several weeks to months. This is a behaviour more common in freshwater fish or cichlids.

“Glancing” Behaviour: Juveniles feed on the mucus secreted from the sides of their parents, a behaviour known as “glancing.” This direct feeding contributes to the young’s survival and growth.

Limited Dispersal: Due to the lack of a pelagic stage, the offspring tend to remain close to the parental reef, leading to high levels of genetic differentiation and local adaptation between populations on nearby reefs.

Aquarium Care
The Spiny Chromis is a hardy and generally peaceful fish, making it a popular choice for marine aquariums, especially the brightly coloured juvenile “Orange Line Chromis.”

Care Level: Easy to Beginner.

Tank Size: A minimum of 30 gallons (approx. 113 liters) for a single fish or small group is often recommended, though a larger tank is better for a mature pair.

Temperament: Generally peaceful, but adults can become territorial and semi-aggressive, especially when guarding a nest or pair-bonding.

Reef Safe: Yes, it is typically considered reef-safe and will not bother corals or most invertebrates.

Diet: An omnivore; it readily accepts a varied diet in the aquarium, including high-quality flakes, pellets, and frozen foods like brine shrimp, mysis shrimp, and chopped meaty foods, as well as marine algae preparations.

Social: It is best kept singly, as a mated pair, or sometimes in small groups (juveniles school more readily). If you intend to keep a group, a much larger tank is necessary to diffuse aggression.

Note on Colouration: While the juveniles are often sold with a bright orange stripe (hence “Orange Line Chromis”), the adult colour can vary significantly by population, ranging from blue-grey to brown to bicoloured (grey/black front, white back).

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