Blue Axil Chromis

The Blue Axil Chromis is an attractive schooling damselfish distinguished by the prominent blue spot at the base of each pectoral fin, which gives the species its common name. The body is a soft silvery-green to olive color with a subtle iridescent sheen, and the distinctive blue axillary spot provides an elegant accent that sets it apart from other Chromis species. At a maximum size of approximately 5 inches, it is larger than many commonly kept chromis but remains a manageable and peaceful community fish.

In the wild, Chromis caudalis inhabits outer reef slopes and lagoon edges throughout the Indo-Pacific, where it forms loose to moderately sized aggregations above coral heads and rocky outcrops. These schools hover in the water column feeding on passing zooplankton, retreating into the reef structure when threatened by predators. The species is often found alongside other schooling chromis and damselfish, contributing to the vibrant clouds of small fish that characterize healthy tropical reef ecosystems.

The Blue Axil Chromis is an excellent choice for aquarists seeking a hardy, peaceful schooling fish with a touch more distinction than the ubiquitous Blue Green Chromis. It is beginner-friendly, readily accepting a wide variety of foods and tolerating minor fluctuations in water quality. For the best visual impact and most natural behavior, keep in groups of 5 or more in an aquarium of at least 55 gallons. Like other Chromis species, a dominance hierarchy may develop in smaller groups, so larger schools in spacious tanks help distribute any mild conspecific aggression. The species is completely reef-safe.