All fish / Pomacentridae

Black-axil chromis

Chromis atripectoralis

Also known as blackaxil chromis, black axil chromis, green chromis, blue green chromis, black-axil puller, blue-green puller, デバスズメダイ, ikan betok laut, 黑腋光鳃鱼, 蓝绿光鳃雀鲷

A small, iridescent blue-green damselfish with a deeply forked tail and a black spot at the base of the inner pectoral fin, the feature that separates it from the very similar green chromis. It is kept for its gentle nature, hardiness and the lively look of a shoal hovering over corals in reef tanks.

Care at a glance

Care level

Easy

Temperament

Peaceful

Adult size

9 cm

Temperature

24 to 28 °C

pH

8.1 to 8.4

Smallest tank

200 litres

Keep as

Group of 5 or more, ideally an odd number in a larger tank

Diet

Omnivore: frozen mysis and brine shrimp, copepods, quality marine flakes and pellets, fed small amounts several times a day

Swims

Middle of the tank

Lifespan

5 to 8 years

Water

Marine (saltwater)

Wild range

Indo-West Pacific, from East Africa to the Great Barrier Reef, Micronesia and Polynesia

Breeding

Males clear a nest site on the substrate and guard demersal eggs laid by several females, which hatch after a few days into tiny pelagic larvae. Spawning sometimes happens in large aquariums, but rearing the larvae needs rotifers and copepods and is rarely achieved at home.

Good to know

Often mixed up with Chromis viridis, which lacks the black pectoral axil; care is the same. Groups can develop a pecking order in small tanks, so weaker fish may be picked off one by one.