Hawaii's Reef Fishes

Filefishes (Monacanthidae)

Barred Filefish (female) Cantherhines dumerilii (Hollard, 1854)

The filefishes are named for their tough, finely abrasive skin. They share many features with the triggerfishes, differing in their more compressed bodies, generally a more pointed snout, a more slender and longer first dorsal spine (also capable of being locked in erect position), a very small second dorsal spine (absent in a few species), and no third dorsal spine.

The dentition is similar but there are 6 teeth in the outer row of the upper jaw and 4 in the inner. The scales have numerous tiny setae which obscure the scale outlines.

Unlike the triggerfishes, many species are able to alter their color to match their surroundings; also many have little cutaneous flaps or cirri that further enhance their camouflage. Because of this and their secretive nature, they are easily overlooked.

Some filefishes are sexually dimorphic, especially with respect to the spines or setae posteriorly on the body (larger in males).

The fishes of this family are mostly omnivorous, feeding on a wide variety of benthic plant and animal life. Some filefishes, such as Aluterus scriptus, ingest noxious sponges and various stinging coelenterates avoided by other fishes. Eight species occur in the Hawaiian Islands, one of which, Thamnaconus garretti (Fowler), is restricted to deep water.

There are more species of filefishes in Australia (where they are known as leatherjackets) than anywhere in the world; they occur along all the coasts of the continent, including the cool southern shore where a surprising 23 species are recorded.

Barred Filefish

Barred Filefish (male) Cantherines dumerilii (Hollard, 1854) O'ili

Grayish brown with indistinct dark brown bars posteriorly on side of body; a pink to whitish submarginal band on lips; males with caudal fin, the 2 pairs of penducular spines, and a large spot in front of each anterior spine orange; juveniles may be white-spotted; dorsal soft rays 34-36.

Attains 15 inches (38 cm). Indo-Pacific and tropical eastern Pacific; often in pairs. Feeds mainly on branching corals, but other invertebrates are also eaten. C.carolae (Jordan & McGregor) and C. albopunctatus (Seale) are synonyms.

Scrawled Filefish

Aluterus scriptus (Osbeck, 1765)

Light bluish gray to olive-brown with blue or blue-green spots and short irregular bands and scattered small black spots; dorsal and ventral profiles of head concave; eye about a half eye diameter from top of head; first dorsal spine long and slender, over eye; soft dorsal rays 43-49; caudal fin very long and rounded. Reaches 30 inches (76 cm). Cosmopolitan in all warm seas. Feeds on algae, gorgonians, stinging coral and other noxious coelenterates, tunicates, and sponges.

All information and pictures in this section are from John E. Randall's Shore Fishes of Hawai'i by permission of the author.