Blackeye Thicklip Wrasse

The Hemigymnus melapterus, commonly referred to as the Blackeye Thicklip Wrasse or Half-and-Half Wrasse, is a distinct species within the Labridae family, indigenous to the Indo-Pacific region.

This particular species exhibits medium body size, with an attainable length of up to 50 centimeters. With a pronounced, laterally compressed body structure, the wrasse features a pronounced cephalic region and a terminal oral cavity with notable lip thickness. Ontogenetic color morphing is apparent in this species, with juveniles displaying a greenish-yellow basal pigmentation complemented by yellow longitudinal stripes, a prominent white oblique band posterior to the gill cover, an orange-hued caudal fin, and a greenish-gray anterior region. The adult females possess a green posterior section beyond the biased line, scale margins tinged with black. Their color scheme involves a sophisticated array of pink stripes with turquoise adornments extending from the snout tip to the cranial region. The terminal phase males, conversely, exhibit an emerald green mark posterior to each scale, a cerulean outline encircling the orbital area, and a green foreground marked with pink and turquoise on the snout and cranial area.

Habitat-wise, this species has a wide distribution across tropical and subtropical waters of the Indo-Pacific domain—spanning the eastern African coastline inclusive of the 🌊 Red Sea, extending to the Polynesian territories, and ranging from 🇳🇨 New Caledonia (🇫🇷 Overseas France) to the southern regions of 🇯🇵 Japan. Favoured habitats include coral formations, rubble zones, and sandy environs predominantly located on outer reef declivities and abyssal drop-offs, reaching a depth of no less than 40 meters. The juvenile population exhibits a more reclusive nature, maintaining concealment within branching coral structures.

The solitary or small aggregation habit of the Half-and-Half Wrasse denotes its social behavior. As a benthic carnivore, its diet primarily comprises small marine invertebrates such as crustaceans, molluscs, annelids, and echinoderms, which are gleaned from the substrate or ensnared within it. This species employs a unique feeding strategy involving the ingestion of sand to filter food particles internally, later expelling non-nutritive granules via the gill operculae.

The reproductive system of the Hemigymnus melapterus aligns with the protogynous hermaphroditic mechanism common to the wrasse lineage. This entails initial female sex assignment with the potential for subsequent male transformation following a specific transitional phase.