Moon Wrasse (Thalassoma lunare) are among the most abundant and frequently encountered members of the Wrasse (Labridae) family found in local waters, and can be found at virtually all reef environments in the area, both inshore and offshore, although seldom deeper than 15 - 20m.
As with many other Wrasses, the Moon Wrasse is a protogynous hermaphrodite, with all individuals beginning life as females in their initial phase before eventually changing to male in their intermediate or terminal phases.
Moon Wrasse are opportunistic carnivores that are constantly on the move within their territory. They are ever watchful for larger foraging fish, or careless divers disturbing the substrate and are usually the first on the scene when food becomes available.
Divers should be especially careful not to swim too close to the brooding sites of other species such as Damselfish as this often results in the parent fish temporarily leaving their eggs unattended, an opportunity that the opportunistic Moon Wrasse rarely miss!
Identification of this species is reasonably easy, particularly the dominant male which has a predominantly brilliant blue colouration with the bright yellow, crescent shaped caudal (tail) fin from which its name is derived.
The upper and lower caudal fin margins, scale margins, dorsal and anal fin bases and patches on the pectoral fins all exhibit a bright purple/violet colouration.
There may also be pale blue/purple streaks radiating from around the eyes.
Females and subordinate males are generally greenish in colour, with varying degrees of blue on the ventral surface (generally decreasing with maturity).
The females and subordinate males also exhibit the purple/violet areas seen on the dominant male, although the lines radiating from the eyes are also purple/violet as opposed to the pale blue of the "alpha male".
A further distinctive marking on females and subordinate males is a prominent dark blotch at the caudal peduncle which fades with maturity.
On very young/small individuals the dark spot on the caudal peduncle is very pronounced and there is also a small dark spot at the base of the dorsal fin. Additionally, there may up to ten short, elongated vertical blue markings emanating from the dorsal edge of the body