Tag: Regal Demoiselle (Neopomacentrus cyanomos)

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.

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.

Alan's picture
Palechin Moray Eel (Gymnothorax Herrei)

In this shot taken at Sail Rock, Koh Phangan, a little Palechin Moray Eel (Gymnothorax Herrei) is being moved along by a group Regal Demoiselles (Neopomacentrus Cyanomos).

Alan's picture
Palechin Moray Eel (Gymnothorax Herrei)

This photo of a Palechin Moray Eel (Gymnothorax Herrei) with a pair of Regal Demoiselles (Neopomacentrus Cyanomos) gives an excellent impression of just how small this species is in comparison to its locally occurring relatives.

Alan's picture
Regal Demoiselles (Neopomacentrus Cyanomos) harass a White-Eyed Moray Eel (Siderea Thyrsoidea)

In this photo, from Sail Rock, a group of juvenile Regal Demoiselle (Neopomacentrus Cyanomos) are "mobbing" a wandering White-Eyed Moray Eel (Siderea Thyrsoidea).

Alan's picture
Regal Demoiselle (Neopomacentrus Cyanomos)

In this photo, many of the traits that are common within the local population of Regal Demoiselle (Neopomacentrus Cyanomos) are clearly visible, namely:

The orange-coloured "ear-spot"
The neon blue fin margins
The white mark at the rear of the dorsal fin
The pale, blotchy markings which may be related to nesting activity

Alan's picture
Regal Damselfish (Neopomacentrus Cyanomos)

Regal Demoiselle (Neopomacentrus Cyanomos) can often be found darting in and out of disused oyster shell, which they use for protection and also as a safe place to lay their eggs, as the individual in this photograph was doing at the time (the eggs are the tiny brownish dots inside the shell).