Reef Blue Chromis (Chromis cyanea)

Also known as: Blue Reef Chromis, Caribbean Blue Chromis

The Reef Blue Chromis is a peaceful, active, and vibrant schooling fish from the tropical Western Atlantic and Caribbean reefs. Known for its shimmering electric-blue body and calm nature, this species brings graceful movement and bright color to both reef and FOWLR aquariums. It is less aggressive than many damselfish, hardy, and easy to care for, making it a favorite choice for beginners and experienced hobbyists who want a peaceful mid-water fish that thrives in groups.

Key Features

• Scientific Name: Chromis cyanea
• Common Names: Reef Blue Chromis, Blue Caribbean Chromis
• Adult Size: ~5–6 inches (≈ 12–15 cm)
• Lifespan: ~5–8+ years with proper care
• Temperament: Peaceful; thrives in groups; rarely aggressive
• Reef Compatibility: Fully reef-safe does not harm corals or invertebrates
• Minimum Tank Size: 55+ gallons for a small group
• Experience Level: Beginner-friendly hardy, adaptable, and easy to feed

Habitat and Tank Requirements

Natural Habitat:

The Reef Blue Chromis lives in shallow Caribbean coral reefs, rocky reef slopes, and lagoon areas where sunlight reaches easily. They usually gather above branching corals, sea fans, or rocky ledges, forming loose groups in the middle of the water column. These structures give them quick hiding spots when predators appear.

Tank Environment:

• Provide plenty of open mid-water swimming space
• Use live rock with caves or branching areas for shelter
• Moderate water flow helps recreate natural reef conditions
• Keep them in groups of 3 or more
• Avoid very small tanks since groups need space

Recommended Water Parameters:

• Temperature: 74–80 °F (23–27 °C)
• Salinity: 1.023–1.026 sg
• pH: 8.1–8.4
• Clean, stable water helps them stay healthy and colorful.

Diet and Feeding

Reef Blue Chromis are planktivores they naturally eat tiny drifting animals in the ocean.

Recommended Foods in Aquariums:

• Mysis shrimp
• Brine shrimp
• Copepods or plankton substitutes
• Marine pellets or flakes
• Enriched frozen foods

Feeding Schedule:

• Feed 1–2 small meals per day
• They prefer floating or moving foods, just like plankton

Behavior and Compatibility

• Very peaceful and social
• Best kept in groups reduces stress
• Active mid-water swimmers
• Rarely aggressive, even as adults

Suitable Tank Mates:

• Gobies
• Wrasses
• Anthias
• Clownfish
• Tangs
• Peaceful reef fish
• Reef-safe invertebrates

Avoid highly aggressive damselfish that may bully them.

Reef Compatibility

• The Reef Blue Chromis is fully reef-safe.
• They do not nip corals, dig, or disturb the aquascape.
• They live peacefully with corals, clams, sponges, and all common reef invertebrates.

Acclimation and Care Tips

• Add only to a stable, fully-cycled tank
• Use slow drip acclimation
• Provide open swimming areas + hiding spots
• Keep them in groups
• Feed small portions regularly

Signs of a Healthy Specimen

• Active and steady mid-water swimming
• Bright electric-blue coloration
• Smooth fins with no tears
• Clear eyes and clean scales
• Good appetite
• No strange spots, gasping, or hiding

Color and Development

• Electric blue body with metallic shine
• Clear to light blue fins
• Juveniles show softer blue; color deepens with age
• Strong lighting + good diet = brighter color
• Color may fade when stressed but returns once stable

Breeding Potential

Breeding Reef Blue Chromis in home aquariums is very rare. In the wild, they breed in large groups. The male chooses a safe spot on a rock where the female lays eggs, and he protects the eggs until they hatch. But in aquariums, it is difficult to recreate these natural conditions because they need a large tank, very stable water, and a peaceful environment. For these reasons, most hobbyists do not see their Reef Blue Chromis breeding in home tanks.

Why Choose a Quarantined Reef Blue Chromis?

A quarantined Reef Blue Chromis ensures you receive a healthy, stress-free fish that has already been observed, treated if needed, and trained to eat prepared foods. During quarantine, the fish is monitored for common marine diseases like ich or velvet, and it is kept in stable water conditions to strengthen its immune system. This helps the fish adjust easily to your main tank, stay active, maintain bright coloration, and live safely with other reef or FOWLR tank mates. Choosing a quarantined specimen greatly increases long-term survival and reduces the risk of introducing diseases into your aquarium.