The Blue Green Chromis (Chromis viridis) has several other English names. These names include the Green Chromis, Blue Green Damselfish, Blue Green Puller, Green Puller, as well as the Blue Green Damselfish. The Chromis viridis has been assessed for the IUCN Red List of Threatened Species.
Geographical range, habitat and habits
The Indo-Pacific is one place where the Blue green Chromis are commonly found. Areas extending from the Red Sea to the Line, Marquesan, and Tuamoto islands are its natural range. Extending to the North, the species are found up to the Ryukyu Islands of Japan. Their range continues down to New Caledonia and southwards.
Blue-green Chromis favour sheltered environments like the sub tidal reef flats and lagoons. They can be found in large schools over thickets of branching corals such as Acropora. They live in the water at a depth range of 10-12 meters or 33-39 feet. Typically younger specimens are found near certain coral heads.
Size and appearance
8.0 cm or 3.1 inches has been the size of the biggest scientifically measured Blue Green Chromis.
As depicted by the name, the Blue Green Chromis vary from pale green to light blue in colour. A yellowish coloration with a blackish posterior develops on the male fish during nesting period.
The Blue Green Chromis (Chromis viridis) are very similar in appearance to the Black-axil Chromis (Chromis atripectoralis), but the distinct black blotch that is found on their inner pectoral axil distinguishes the Black-axil Chromis. Moreover, the Blue Green Chromis are, under normal circumstances, smaller in size than the Black-axil Chromis. The black spot is very small and hard to envisage in some specimens of the Black-axil Chromis.
Caring for the Blue-green Chromis
The Blue-green Chromis happen to be a forbearing marine fish that can be recommended to beginner or inexperienced saltwater aquarists. They should be kept in the tank in groups of not less than six fish. They can begin pecking each other but within the group they stay relatively tranquil in the aquarium. Though the Blue-green Chromis are one of the most peaceful damselfishes, they sometimes develop a bit of aggression towards other species during breeding time.
Six Blue-green Chromis fish require space of not less than 30 gallons or 115 litres of water in an aquarium. The temperature of the water should not fall out of the range of 22-27° C or 72-80° F. And the recommended value of pH is 8.1-8.4 and a carbonate hardness of 8 – 12° dKH is advisable. The specific gravity of 1.020-1.025 is optimal.
The Blue Green Chromis are considered a reef-safe creature and can be kept together with corals.
Feeding Blue-green Chromis
In the wild, Blue-green Chromis feed on phytoplankton, but most types of food in the aquarium will be acceptable for them. The fish need numerous feedings of small portions as opposed to a single bulk meal. The fish can be fed on flake food mixed with frozen fresh and live food. Some algae or algae based food is recommended, since the fish always take in a certain amount of algae in their natural environment. A varied diet is recommended for the good health of the Blue-green Chromis.
Breeding of the Blue-green Chromis
The Blue-green Chromis breed on sand and rubble. The male fish build the nest which can be shared by several female fish. The females typically lay a large number of eggs that fill up the nest and normally hatch within 2-3 days time. It is the male’s duty to guard the nest and to fan fresh water over the eggs using his caudal fin. Eggs that fail to hatch are eaten by the male as a measure to prevent them from turning into breeding grounds for bacteria and fungi that may risk the life of the offspring. When nesting, males turn yellowish in colour. The Blue-green Chromis can become more aggressive than usual during the breeding period.
Good optimal water conditions and plenty of live food appear to trigger spawning in Blue-green Chromis species.