Colours

Distinguishing features

A small blue-grey fish with orange-yellow on the rear dorsal fin and a yellow tail, and a small dark "ear-spot" behind the eye. Usually seen schooling above corals in shallow water, often in mixed schools with the congeneric N. cyanomos. N.azysron is distinguishable by the contiguous yellow which connects the rear of the dorsal fin with the tail, and the blue-grey as opposed to charcoal grey body colour. When the two species forage in mixed schools, the N. azysron usually aggregate together at the leading edge of the school, highest in the water column and furthest from shelter.

Size

Depth range

Synonyms

Distribution

Distribution and habitat preferences

Found in nearly all habitats around the island, although most common in shallow lagoonal and backreef areas with abundant hard coral and good current flow.

Found in most locations around the Island.

Behaviour

The Yellowtail Demoiselle is a common plankton feeding damselfish found all around Lizard Island and throughout the GBR. It aggregates in large schools over the top of suitable hard coral shelter, and is commonly targeted by predators such as Trevallies and Rock Cods. Despite its abundance, there is little published information on the ecology of this species. Like other damselfish, the males establish a benthic nest and court females to encourage egg deposition, and the eggs hatch after a short incubation of 3-5d. The juveniles settle to the reef in large groups, and take up position next to the adult feeding schools. At Walker Reef, we found this species recruited in large groups to the backreef habitats during summer, and then progressively moved into the other lagoonal habitats during the early autumn. Populations of the Yellowtail Demoiselle appear to have rapid turnover which suggests this species is relatively short-lived.

Web resources

References