Blue Reef Chromis (Chromis cyaneus) Care Guide
Chromis cyaneus is a bright blue planktivorous damselfish of the western Atlantic and Caribbean, now reclassified by FishBase as Azurina cyanea.
Compiled by Aquairi from published sources · Published · Updated
Overview
Chromis cyaneus, the blue chromis, is a vivid blue damselfish of the family Pomacentridae from the western Atlantic. FishBase and Wikipedia now place it in the genus Azurina (Azurina cyanea), the Caribbean counterpart of the Indo-Pacific green chromis.
Taxonomy
- Family: Pomacentridae
- Genus: Chromis
- Scientific name: Chromis cyaneus
- Current placement: Azurina cyanea (FishBase)
Habitat
The species occurs in the western Atlantic around Bermuda, southern Florida, the Bahamas, the Gulf of Mexico and the Caribbean Sea. It is reef-associated, commonly found at 3-5 m but recorded down to 60 m, swimming in the water column above outer reefs and retreating into coral crevices when frightened.
Tank requirements
- Minimum tank volume: 200 L
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Specific gravity: 1.024-1.026
- Carbonate hardness (dKH): 8-12
- School size: 6 or more individuals
- Adult size: up to about 15 cm
- Lifespan: 8-15 years
Diet
In the wild it feeds on small zooplankton, primarily copepods, taken from the water column above the reef. In the aquarium an omnivorous diet of small frozen and prepared marine foods fed two times daily is suitable.
Compatibility
A peaceful mid-water species that often associates with creole wrasse in the wild. It mixes with clownfish, tangs, wrasses and gobies. Aggressive damselfish and predators such as lionfish should be avoided.
Reef compatibility
The blue chromis is reef-safe and does not damage corals or invertebrates. It uses coral crevices for shelter, fitting reef aquariums with moderate flow.
Breeding
Reproduction involves distinct pairing. Eggs are demersal and adhere to the substrate, and males guard and aerate them. Captive breeding is considered difficult.
Conservation status
IUCN Red List: Least Concern. The species is considered abundant within its range despite pressure from the aquarium trade, lionfish expansion and coral loss.
Blue Reef Chromis Breeding Guide
Overview
Chromis cyaneus (recognised by FishBase under the current name Azurina cyanea) is a Western Atlantic damselfish of Bermuda, southern Florida and the Caribbean Sea, reaching about 15 cm. Adults congregate above deep outer reefs and feed on zooplankton, mainly copepods. FishBase records it as oviparous with distinct pairing during breeding, with demersal eggs that adhere to the substrate and male parental care. IUCN status is Least Concern.
Sexing
Like other Pomacentridae, this chromis shows little permanent external difference between the sexes outside the breeding season. Sex is most reliably inferred from spawning behaviour: the male establishes and tends a substrate nest, while the female is the partner that enters it to deposit eggs. Working from a group rather than a single chosen pair gives the best chance of a compatible male and female forming naturally.
Conditioning
A school held in spacious, stable reef conditions and fed several times a day on small zooplankton-type foods comes into condition. Because the wild diet is dominated by copepods, frequent feeding of fine planktonic and meaty foods supports egg production and reflects the natural feeding ecology recorded on FishBase.
Breeding Setup
A pomacentrid nest requires open, defensible substrate. The male clears an area of algae and invertebrates to create a nest site on hard substrate, so the breeding system should provide flat rock or a similar firm surface within a territory the male can defend. A roomy tank allows the school to function while a pair separates to spawn.
Spawning Behavior & Trigger
Damselfish engage in ritualised courtship displays such as rapid bursts of motion, chasing and wide fin extension. The male swims behind the female as she lays a string of sticky eggs that attach to the cleared substrate, and fertilises them externally. FishBase notes distinct pairing during breeding for this species.
Egg & Fry Care
The eggs are demersal and adhere to the substrate, and the male guards and aerates the clutch. Across Pomacentridae the eggs hatch in roughly two to seven days, releasing tiny larvae of about 2 to 4 mm that enter a pelagic stage lasting from about a week to over a month depending on species. These larvae require very small live planktonic foods such as cultured copepods.
Common Challenges
The principal obstacle is the pelagic larval phase: the larvae are minute and pelagic and demand a continuous supply of correctly sized live plankton, so rearing is generally restricted to specialist culture facilities rather than home tanks. Until species-specific larval protocols are published, home spawning typically ends at the planktonic stage.