The fish Chromis atripectoralis is known under several different names, including Black-axil Chromis, Black Axil Chromis, Blackfin Chromis, and Blue-green puller. It is also sometimes sold under the name Green Chromis, but this can lead to confusion since that name is commonly used for the species Chromis viridis (also known as Blue-green Chromis) as well.

Chromis atripectoralis has not been evaluated for the IUCN Red List of Threatened Species.

Geographical range, habitat and habits

The Black-axil Chromis lives in the Indo-Pacific, from the Ryukyu Islands of Japan down to Western Australia. It can be found around most of the islands of Oceania, with the exceptions of Hawaii and the Pitcairn Group. Its range proceeds from approximately 30°N to 32°S.

The Black-axil Chromis inhabits clear lagoons passages and seaward reef slopes. It is known to appreciate thickets of live or dead coral and large schools can be observed feeding over branching Acropora corals. The depth range for this species is 1-29 meters / 3-95 feet.  

Size and appearance

The largest scientifically measured Black-axil Chromis was 12 cm / 4.7 in.

The Black-axil Chromis has uniform blue green colour.  This fish is often confused with the (typically smaller) Blue-green Chromis (Chromis viridis) since they look very similar to each other. You can however recognize the Black-axil Chromis by the distinct black blotch that is present on the inner pectoral axil. In some specimens, the black spot is really small and hard to notice.

Black-axil Chromis care

It is not advisable to house Black-axil Chromis in aquariums smaller than 55 gallons / 208 litres. This species live in large schools in the wild and should only be kept in groups consisting of at least five individuals in the aquarium. Not keeping it in a group can have a negative effect on its health.

It is normal for the dominant fish to bicker with the others; in a large enough aquarium they will usually sort these things out on their own without inflicting any injury. If the other members of the group seem to be seriously disturbed by the bickering, the group is most likely too small.

The Black-axil Chromis is considered reefs safe. It can be kept in peaceful community aquariums.

The recommended pH-range is 8.1-8.4 and the specific gravity should be kept in the 1.020-1.025 range. The water temperature should be 24-27° C / 75-81° F.

Feeding Black-axil Chromis

In the wild, the Black-axil Chromis feeds chiefly on amphipods, copepods and zoea. (Zoea is the larval stage of certain decapod crustaceans.) It is important to provide it with a varied omnivore diet in the aquarium. Feed your fish several small meals throughout the day instead of just one or two large ones.   

Breeding Black-axil Chromis

We don’t have any information about breeding Black-axil Chromis in aquariums.

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