Thalassoma trilobatum (Lacepède, 1801)

Dorsal and Anal Fin Structure

The Christmas wrasse, Thalassoma trilobatum, has 8 spines and 13 soft rays in its dorsal fin, and 3 spines and 11 soft rays in its anal fin.

Pectoral Fin and Lateral Line Scales

It normally has 16 pectoral fin rays and 25 scales along the lateral line.

Caudal Fin Sexual Dimorphism

In the initial, female phase, the caudal fin is slightly rounded or truncate; in the terminal, male phase, the caudal fin is truncate or slightly double emarginated.

Female Body Coloration and Pattern

Females have a greenish grey to pale green body, with 5 to 6 dark blotches along the back, two poorly defined dark stripes on the flank, and a dark vertical line on most body scales.

Female Facial Marking

They also have a diagonal or C-shaped pink to dark red marking below the front of the eye.

Terminal Male Body Coloration

Terminal phase males have a salmon-pink to orange body colour that is most intense toward the head, with two horizontal rows of vertically oriented green rectangles.

Male Body Pattern Detail

Every fourth pair of rectangles in the upper row extends to form a single green bar across the back.

Male Head and Tail Coloration

The male's head is orange-brown and has no bands, while the tail is brownish to greenish, fading to pink toward the margin, with the fin rays in the last third of the tail coloured blue.

Similar Species Distinction

This species is similar to the surge wrasse (Thalassoma purpureum), but can be distinguished by the spotted head of female Christmas wrasses, the absence of a V-shaped mark on the snout, and the distinct head colour of males.

Maximum Length

Christmas wrasses can reach a maximum total length of 30 centimetres (12 in).

Taxonomic History

This species was first formally described in 1801 by French naturalist Bernard Germain de Lacépède (1756–1825) under the name Labrus trilobatus, with the type locality given as Mauritius.

Overall Distribution Range

It has a wide distribution across the Indo-Pacific.

Indian Ocean Distribution

It occurs along the east coast of Africa from Somalia to South Africa, with no confirmed records from Madagascar, and ranges across the Indian Ocean east into the Pacific Ocean as far as Pitcairn Island.

Pacific Ocean Distribution

In the Pacific, its range extends north to the Ryukyu Islands and south to northern New South Wales.

Habitat and Depth Range

The Christmas wrasse inhabits wave-exposed reef margins and reef flats with mixed coral, algae, and seagrass, and occurs at depths between 0 and 10 metres (0 and 33 ft).

Adult Diet

It is a carnivorous species that feeds on a variety of small invertebrates including crabs, molluscs, and brittle stars.

Juvenile Diet

Younger fish feed mainly on small benthic invertebrates.

Reproduction and Larval Stage

Christmas wrasses are oviparous; males and females form pairs to spawn, and after eggs hatch, the larval stage lasts between 60 and 99 days.