When a marine aquarist is looking for a fish to include in his/her aquarium community there are some requirements such as hardiness, compatibility and colour. The Blue Chromis, properly called Chromis cyanea, is a definite contender. It’s home world is the Caribbean and the fish is beautiful without a doubt, catching the eye. There is also the Green Chromis, properly called Chromis viridis but, to my eye anyway, the blue is the more attractive. The Green Chromis from the Indo-Pacific has the same requirements as the blue.
To fit into a community in an average size home aquarium fish should not be over large. Some fish are fine on purchase but they grow and surprise the inexperienced aquarist. The Blue Chromis will not, getting to around 2.25ins (circa 8.0cm).
Fish should also not be over aggressive and again the fish meets requirements as it is reasonably sociable. There is one sociability requirement though that needs to be known and that is to keep more than two of these fish. If two are kept it is quite possible that in time there’ll be only one. This could be because of territory troubles. The fish will shoal and there should be three or more, a fact that needs to be taken into account when the total number of fish the aquarium can hold is considered. Perhaps three of the fish would be ideal for a mini-reef.
Another important consideration is overall hardiness. The Blue Chromis is a damselfish and it’s generally hardy. However, it is not as hardy and forgiving as some others of the family, seawater quality needs to be high with regular partial seawater changes – seawater quality is normally the main focus of an aquarist so there shouldn’t be a problem. To be certain perhaps it’s better to leave the Blue Chromis addition until the aquarist has, say, six months or so experience.
Feeding is one area where some aquarium occupants could be a problem. Not so the Blue Chromis. In nature’s wild world they are plankton feeders and of course this continues in the aquarium with the plankton becoming flake or de-frozen foods. They feed well and easily.
The fish is well suited to a reef aquarium, there isn’t any threat to corals etc. A reef aquarium can house less fish so the need for at least three as a shoal needs to be born in mind.
It’s possible that the aquarium will hold smaller fish than the Blue Chromis. This is fine, the fish pose no threat to others, smaller or not. As usual, it must be kept in mind that there shouldn’t be any other fish, larger or not, that are over aggressive. Blue Chromis need a reasonably peaceful environment.
As said, Blue Chromis are lovely and easy to keep. Having them in a small shoal above the reef gives colour and impact. Ensuring that seawater quality is high is a given anyway (or certainly should be!) and not an extra in effort. These fish are another easy to keep gift from nature.