Blue Reef Chromis

Blue Reef Chromis (Chromis cyanea): The Electric Blue Schooler

The Blue Reef Chromis (Chromis cyanea) is one of the most popular and visually striking damselfish species in the marine aquarium hobby. It is highly valued for its intense electric blue coloration and its active, schooling behavior, which brings life and movement to the mid-water column of the reef tank.

The Blue Reef Chromis features a brilliant, saturated electric blue body with an elongated, deeply forked tail. Mature males often develop dark or black margins on the dorsal and caudal fins. Unlike the related Blue/Green Chromis (C. viridis), C. cyanea maintains a deeper, more fluorescent blue color, making it an excellent addition to showcase vibrant reef lighting.

This species is a planktivore and is naturally found in large, active schools over coral reefs. To replicate their natural social structure and minimize territorial aggression, they are best kept in odd-numbered groups of three or more, though groups of five or more are ideal for long-term success.

Care & Compatibility:

• Diet: The Blue Reef Chromis is an Omnivore/Planktivore and feeds constantly in the wild. They require a varied diet, primarily consisting of high-quality marine flake food, pellet food, and small meaty frozen foods like Mysis shrimp, Artemia (Brine shrimp), and finely chopped seafood. Frequent, small feedings (3-4 times daily) are crucial due to their high metabolism.
• Temperament: Generally Peaceful, especially when housed in a school. However, if kept singly or in pairs, they can become territorial or aggressive toward smaller, less aggressive tankmates. Keeping them in an appropriately sized group diffuses aggression among themselves.
• Reef Compatibility: Excellent (Reef Safe). They pose no threat to corals (SPS, LPS, or Soft Corals), ornamental shrimp, or other invertebrates. They actively swim in the water column and rarely disturb the substrate.
• Tank Requirements: While a single specimen can live in a 30-gallon tank, a school requires 75 gallons or more to provide adequate swimming space and minimize territorial stress among the group. They require strong, turbulent water flow to simulate their natural reef environment.
• Acclimation & Health: They are relatively hardy once settled, but they are planktivores that rely on constant food intake. They should be observed closely during acclimation and quarantine to ensure they are eating immediately.

Quick Facts

• Scientific Name: Chromis cyanea
• Primary Common Name: Blue Reef Chromis
• Other Common Names: Blue Chromis, Deep Blue Damsel
• Origin: Western Atlantic Ocean (Caribbean, Florida, Bahamas)
• Maximum Size: 3.5 – 4 inches (8-10 cm)
• Temperament: Peaceful (Best kept in schools)
• Diet: Omnivore/Planktivore
• Minimum Tank Size: 75 Gallons (For a school of 5+)
• Reef Compatibility: Excellent (Reef Safe)
• Care Level: Easy to Moderate