Diving with Filefishes

Lanta Marine Life | Monacanthidae

Filefish are rhomboid-shaped fish with with deep keeled bodies and can appear very similar to triggerfish, their close relatives. We have several species of filefish at the dive sites around Koh Lanta.

Filefish have very thin (laterally compressed) bodies, small snouts and mouths with projecting incisor teeth. The eyes are located high on the head.

Filefish vary in size from around 20 cm up to about 60 cm for the largest species, the scribbled filefish, which is often found at the dive sites around Koh Lanta.

This family of fish have a slender, retractable dorsal fin spine on the top of the head, and in most species, there is a second, smaller dorsal fin spine, which is used to lock the first spine into an erect position. The remaining fins are simple, soft fins, with small pectoral fins and a short, fan-shaped tail fin. Scales are very small, giving the skin a rough leathery feel, hence the other common name 'leatherbacks'.

Filefish are bottom-dwelling and can be found solitary, in pairs, or small groups. Filefish are slow swimmers, in part due to their small, soft fins.

Some species feed on algae, others on small invertebrates, including sponges, plants, gorgonians and hydrozoans. Some species eat corals and zooplankton.

3 species found on this page:

Scribbled Filefish (Aluterus scriptus)
Barred Filefish (Cantherhines dumerilii)
Wirenet Filefish (Cantherhines pardalis)

Scribbled Filefish

(Aluterus scriptus)

Aluterus scriptus @ Koh Bida

The Scribbled Filefish has a pale grey body colour, with many small greyish-brownish spots, darker on the upper body and head, lighter on the lower body. There are larger, darker spots to the rear of the body, and on the tail fin base. There are irregular bright blue lines and spots on the body.

The unusually long rounded tail fin is pale with fine black streaks.

The Scribbled Filefish grows to 110 cm and is one of the larger species seen around the southern Andaman coral reefs.

The diet includes algae, seagrass, hydrozoans, gorgonians and anemones.

Barred Filefish

(Cantherhines dumerilii)

Cantherhines dumerilii @ Koh Haa

The Barred Filefish has a yellowish-brown to greyish-brown body with around 12 faint dark vertical bars along the side of the body. The eyes are yellow and the lips are white. The dorsal, anal and pectoral fins are yellowish. The tail fin is a dusky orange colour.

The Barred Filefish grows to 38 cm, though more usually observed around 20 cm - 25 cm. The diet includes acropora branching coral polyps, algae, sponges, sea urchins and mollusks.

Wirenet Filefish

(Cantherhines pardalis)

Cantherhines pardalis @ Koh Haa

The Wirenet Filefish has a bluish-grey to bluish-brown body. The head has numerous wavy diagonal bluish or purplish stripes and the body has a bluish honeycomb, or wire-net like pattern.

The top of the tail base usually has a white spot. The fins are yellowish.

The Wirenet Filefish grows to 25 cm and is usually seen around the outer reef areas. This is a less commonly seen species, feeding on bottom-dwelling invertebrates.