The Regal Demoiselle (Neopomacentrus cyanomos) is one of the most abundant members of the Pomacentridae family in local waters.
Growing to a maximum length of around 10cm, the Regal Demoiselle is fairly easy to identify with its overall dark green colouration, although it sometimes exhibits pale blotches, the appearance of which may be linked to the nest guarding period, in the same way as the nest guarding adults of its relative, the Green Chromis (Chromis cinerascens) shows a similar change in colouration around the same period.
Although this wide-spread species often displays yellow markings at the rear of the pectoral and caudal fins in other locations, i have yet to see this variation in local waters.
It seems that the local variant is always characterised by the presence of a white marking at the rear of the dorsal fin base.
Mature adults have a proportionately long, forked caudal fin which may be either unmarked or mostly white, with the upper and lower edges being the same colour as the body. The forked caudal fin of juveniles is far less elongated.
The pectoral fin rays, and the margins of all of the other fins may be a neon blue colour, as may the edges of the lower 3 or 4 rows of body scales.
A characteristic of local populations of this species is the presence of a distinctive orange-coloured "ear spot" on some individuals, whilst others have the more commonly described dark/black "ear spot".
So far, i haven't seen any mention of this orange-coloured marking in any reference material, although it's possible that this may be a male/female variation.