Pinnate Batfish

Platax pinnatus is a fish from the western Pacific that occasionally is kept in marine aquariums.

Description

As a juvenile it is brown with orange stripe outlining its entire body. This fish grows to a maximum size of 45 cm (18 in). Adults dull silver with short fins. Body orbicular and strongly compressed, its depth more than twice length of head and 0.9 to 1.3 times in SL. Head length 2.9 to 3.8 times in SL. Large adults (above 35 cm SL) with protruding snout, the front head profile distinctly concave. Interorbital width 34 to 42% head length. Jaws with bands of slender, flattened, tricuspid teeth, the middle cusp about twice length of lateral cusps. Vomer with teeth, but none on palatines. Three or 4 pores on each side of lower jaw. Preopercle smooth. Opercle without spines. Dorsal spines (total): 5 - 6; Dorsal soft rays (total): 34-37; Anal spines: 3; Anal soft rays: 24 - 28.

Distribution

Western Pacific: Ryukyu Islands to Australia.

Habitat

Adults are generally solitary and found under overhangs of steep outer reef slopes to a depth of at least 20 m. Juveniles are encountered in mangroves and inner sheltered reefs where they seek shelter in caves or under ledges. Feeds on algae as well as jellyfish and other gelatinous zooplankton. Sometimes adults are seen in large schools travelling over open substrate.

In the aquarium

The pinnate batfish is occasionally kept in marine aquariums

In the wild

Platax pinnatus has been observed to significantly reduce algal growths on coral in studies simulating overfishing on the Great Barrier Reef.