Blue Reef Chromis

The Blue Reef Chromis (Azurina cyanea, formerly Chromis cyanea) is a brilliant Caribbean saltwater fish prized for its intense electric-blue coloration and active, open-water swimming behavior. Its streamlined body can appear cobalt, turquoise, or deep blue depending on the aquarium lighting, with dark edging along portions of the dorsal and tail fins adding contrast. Unlike many damselfish, this species is generally peaceful and works especially well in community reef displays.

Native to the Western Atlantic, the Blue Reef Chromis occurs from Bermuda and southern Florida through the Bahamas and Caribbean. In nature, adults gather above outer reefs where they feed on zooplankton in the water column, retreating quickly into coral and rocky crevices when threatened. This combination of open-water activity and schooling behavior gives the species excellent movement and visual impact in a marine aquarium.

Hardy once established, coral safe, and typically accepting of prepared foods, the Blue Reef Chromis is suitable for both reef aquariums and peaceful fish-only aquariums. It may be kept singly, although a properly sized aquarium can accommodate a group and better showcase its natural social behavior.

Quick Care Guide

Care Level: Easy
Minimum Tank Size: 55 gallons
Temperament: Peaceful
Diet: Omnivore / Planktivore
Reef Safe: Yes
Region: Western Atlantic — Bermuda, southern Florida, Bahamas, and Caribbean
Scientific Name: Azurina cyanea (formerly Chromis cyanea)

Tank Requirements

A 55-gallon or larger established saltwater aquarium provides appropriate swimming room for the adult Blue Reef Chromis, particularly when maintaining more than one individual. This is an active open-water species that benefits from horizontal swimming space rather than an aquarium packed completely with rockwork.

Provide substantial live rock arranged with caves, crevices, and overhangs where the fish can retreat when startled or resting. Maintain plenty of unobstructed water column above and around the reef structure for normal swimming and feeding behavior.

Moderate to strong reef-style water movement is appropriate and helps create the well-oxygenated environment associated with its natural outer-reef habitat. No specialized substrate is required.

Groups require additional space because social hierarchies can develop in captivity. A larger aquarium with multiple retreat areas and broken lines of sight helps reduce persistent chasing between individuals.

A securely covered aquarium is recommended, particularly during acclimation or when introducing new tankmates.

Diet and Feeding

In the wild, the Blue Reef Chromis feeds extensively on zooplankton, with copepods making up an important portion of its natural diet. In captivity, it usually adapts readily to a varied selection of prepared marine foods.

Offer mysis shrimp, enriched brine shrimp, copepods, finely chopped marine seafood, frozen plankton blends, quality marine pellets or flakes, and balanced omnivore preparations. Foods containing marine algae can also be included as part of a varied diet.

Because this species naturally feeds repeatedly from the water column, one to two small feedings per day are appropriate, with more frequent small portions beneficial when practical. Distribute food through the water column so all members of a group have an opportunity to feed.

Temperament and Tankmates

The Blue Reef Chromis is generally peaceful and is significantly less territorial than many traditional damselfish. It mixes well with a broad range of community marine fish, including clownfish, gobies, blennies, cardinalfish, peaceful wrasses, tangs, anthias, and other non-predatory species.

It may be kept singly or in a group. When maintaining several individuals, introduce them together when possible and provide ample swimming room and numerous retreat areas.

Although commonly described as a schooling or shoaling fish, groups maintained in aquariums can develop a social hierarchy. Dominant individuals may occasionally chase weaker members, particularly in smaller tanks or groups with limited hiding space. Monitor grouped specimens for persistent harassment or individuals that stop feeding.

Avoid keeping this peaceful species with highly aggressive damselfish, large predatory fish, or tankmates that continually prevent it from feeding.

Reef Compatibility

The Blue Reef Chromis is considered reef safe. It does not normally consume or damage SPS corals, LPS corals, soft corals, clams, or ornamental reef invertebrates.

Its natural feeding behavior is focused primarily on small planktonic organisms suspended in the water rather than sessile reef animals. It can therefore be maintained confidently in established mixed reef systems.

Its bright coloration and tendency to swim above the rockwork make it particularly effective for adding visible movement to the upper and middle portions of a reef aquarium.

Water Parameters

Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Maintain stable, well-oxygenated seawater and avoid sudden changes in temperature, salinity, or other major parameters. Consistency is more important than targeting one exact value within these ranges.

Common Considerations

• Adults can reach approximately 5–6 inches and benefit from substantial open swimming space.

• Groups can develop a dominance hierarchy, so watch for persistent chasing or weaker individuals being excluded from food.

• Provide caves and crevices within the rockwork so fish can retreat quickly when startled.

• A varied diet rich in small planktonic and meaty foods closely matches the species’ natural feeding habits.

• The species is coral safe and generally compatible with ornamental invertebrates, making it an excellent choice for reef aquariums.