The damselfishes in the Genus Microspathodon reach relatively large sizes of around 20 cm. M. chrysurus is no exception. In nature these animals feed mainly on algae and small crustaceans which they find in their territories on outer reef areas, close to the water surface.
Juveniles are mainly found between the branches of fire coral (Millepora sp.), whose polyps they sometimes consume. From there the brightly colored damselfish often offer cleaning services to larger fish.
With age the coloration turns into a dull brownish-grey and their tail becomes bright yellow. And also their behavior changes: they become more territorial.
In the US, where the species is kept more often, they are regarded as one of the most aggressive damselfish, which should only be kept in large systems and with other large fish.
The image above has been taken by user Goonie in Cuba and submitted to us for identification.