Moon Wrasse

The moon wrasse (Thalassoma lunare), also known as the crescent wrasse or lyretail wrasse, is a species of wrasse commonly found in the 🌊 Indian Ocean and the western 🌊 Pacific Ocean. This species predominantly inhabits coral reefs and surrounding areas at depths ranging from 1 to 20 meters (3.3 to 65.6 feet). As carnivorous fish, moon wrasses primarily feed on fish eggs and small benthic invertebrates. They can grow up to 45 centimeters (18 inches) in total length and hold minor significance in local commercial fisheries, as well as being traded within the aquarium industry.

Juvenile moon wrasses exhibit a distinctive blue coloration on the lower portion of their bodies, featuring a black spot on the dorsal fin and a black mark at the base of the caudal fin. Upon maturation, the black spot develops into a yellow crescent, giving rise to their common name. Their bodies display vibrant green hues with prominently marked scales, and their head coloration varies from blue to magenta with a distinctive broken checkerboard pattern.

Moon wrasses are characterized by their dynamic and territorial behavior, often engaging in nipping and chasing activities. As diurnal creatures, they possess strong vision and an adequate sense of smell. At night, they seek refuge in crevices, frequently positioning themselves beneath rocks. When required, they may clear space beneath these rocks by persistently swimming through them until they achieve a comfortable fit.

These fish are protogynous hermaphrodites, initially starting life as females before undergoing a transformation to males, a process that takes approximately 10 days in moon wrasses. Some individuals form groups consisting of a dominant male and a harem of about a dozen other wrasses, composed of both females and males. The alpha male exhibits enhanced color vibrancy and during low tide displays a green-to-blue color transition while asserting dominance over the group. During breeding season, particularly before high tide, the alpha male turns fully blue to initiate spawning activities with the females.

In captivity, moon wrasses may live up to ten years, although their lifespan is shorter in natural environments. They are valued in the aquarium trade for their resilience, vivid coloration, and engaging behavior. Notably, they are capable of withstanding nitrite spikes and are effective against bristle worms, which are commonly considered pests in aquariums.