Plectorhinchus chatodonoides

The harlequin sweetlips, also called the clown, spotted, or many-spotted sweetlips, is a marine fish in the grunt family. It lives in the Indo-Pacific. Local fisheries catch it in small numbers, and it also appears in the aquarium trade.

Description

This fish has thick lips that swell more as it gets older. Its chin has six pores but no central pit. The dorsal fin usually has 12 spines (rarely 11) and 18 to 20 soft rays, with the soft part about as tall as its base. Young fish are brown with large, separate creamy white blotches that later develop brown spots.

Adults turn grayish with big dark brown spots, each spot wider than the eye. They can reach 72 cm (28 in) long, though 60 cm (24 in) is more common, and weigh up to 7 kg (15 lb). Juveniles may mimic poisonous flatworms (Batesian mimicry). Their tail fin is deeply forked with wide, rounded lobes that are mostly white with a large brown spot; in adults, the tail is less forked.

Distribution

The species ranges from the Maldives and Mauritius east to Tonga, north to the Ryukyu Islands, and south to the Great Barrier Reef. One was seen off St. Martin in the West Indies in 2007, likely released from an aquarium.

Habitat and biology

Adults live alone near ledges or caves in clear lagoons and seaward reefs, hiding during the day. Juveniles shelter in corals. They hunt at night, eating bottom-dwelling invertebrates like crustaceans and molluscs, as well as fish. Young fish often swim head-down with wiggling fins, possibly mimicking toxic flatworms or nudibranchs to avoid predators.

Systematics

French naturalist Bernard Germain de Lacépède first described the species in 1801, without giving a type locality (likely somewhere in modern Indonesia). The name chaetodonoides means "having the form of Chaetodon," which at the time included both butterflyfish and marine angelfish, referring to the serrated gill cover and the then-assumed close relationship with that genus.

People catch these fish with handlines and spears. They are sold fresh or salted. Larger ones have coarse, dry meat. Colorful juveniles are collected for aquariums, and overexploitation may occur in some areas.