Diving with Sweepers

Lanta Marine Life | Pempheridae

Sweepers are a family of small to medium sized fish with 26 members, of which two species are commonly spotted diving from Koh Lanta. Reaching up to 22 cm for some species, they have compressed (flat), elongated, and deep bodies.

This family have large eyes and a short dorsal fin, which can often be higher than it is long. The dorsal fin is much shorter than the extensive anal fin. Sweepers range in colour from bronze to silvery brown with dark dorsal-fin tips and forward anal fin tips.

Sweepers live in relatively shallow water and are often found in schools in caves, under ledges, and in the many nooks and crannies found on coral reefs. This family are often found sharing these hiding places with soldierfish, squirrelfish and cardinalfish.

Sweepers are nocturnal feeders and at night they disperse to feed on zooplankton, crustaceans and bristle-worms.

2 species found on this page:

Vanikoro Sweeper (Pempheris vanicolensis)
Copper Sweeper (Pempheris oualensis)

Vanikoro Sweeper

(Pempheris vanicolensis)

Pempheris vanicolensis @ Koh Phi Phi

The vanikoro sweeper has a copper-brown or bronze body colour and large eyes with a short snout. The dorsal, tail and anal fins are all white with a black margin or tip. The pectoral fins are brownish orange-yellow. The dorsal fin is very short, usually higher than it is long, and much shorter than the anal fin.

The vanikoro sweeper grows to 20 cm, but usually observed smaller, in the 10 - 15 cm range. This species is normally seen in schools of several hundred individuals and is often seen in protected areas during the day, such as caves, caverns and swim-throughs. Individuals and pairs may shelter under rocky or coral ledges and crevices. At night they disperse to feed on crustaceans and bristle-worms worms.

Copper Sweeper

(Pempheris oualensis)

Pempheris oualensis @ Koh Phi Phi

The copper sweeper has a copper-brown to bronze body. The dorsal and tail fins are the same colour as the body. The dorsal fin has a back tip. The anal fin is white, with a dark margin toward the bottom.

This species can be easily identified by the black spot at the pectoral fin base.

The copper sweeper grows to 22 cm, but usually observed smaller, in the 10 - 15 cm range.

This species is normally seen in schools alongside the Vanikoro sweeper and feeds on crustaceans and bristle-worms worms.