Forktail Rabbitfish

The streamlined spinefoot has a body which is oval, compressed, slender and fusiform, the body has a standard length which is 2.4 to 3 times its depth. The small head does not have a steep dorsal profile byt has a pointed snout. The front nostril has a flap which extends past the rear nostril. There is a procumbent spine at the front of the dorsal fin which is enclosed in the skin of the nape. The dorsal fin contains 13 spines and 10 soft rays while the anal fin has 7 spines and 9 soft rays. The caudal fin has a deep fork. This species attains a maximum total length of 40 cm (16 in), although 25 cm (9.8 in) is more typical. The colours of this species are that blue on the upper body with a silvery lower body. They frequently have variable markings, spots and curved lines, particularly on the lower flanks. The eye has a silvery-yellow iris. The axil of pectoral fin is yellow and there is normally a yellow stripe along the base of the dorsal fin. There is also a dark brown bar on the upper edge of the operculum. This fish changes colour when alarmed or asleep to pale and dark brown mottling, with dark areas forming 7 diagonal zones across the flanks and the fins becoming mottled.

The streamlined spinefoot has a wide Indo-Pacific distribution from the Red Sea south to Mozambique and Madagascar and east into the Pacific Ocean as far as Pitcairn Island, north to Japan and south to Australia. In Australia it is distributed from the area of Shark Bay in Western Australia to the Ashmore Reef in the Timor Sea, and on the east coast from the northern Great Barrier Reef near Cape York south to Moreton Bay in Queensland, it also occurs on reefs in the Coral Sea and at the Cocos (Keeling) Islands. It has been recorded once in the Mediterranean Sea off Libya but how this specimen reached there is uncertain. At remote islands such as Rapa, Pitcairn and the Line Islands this species may be the only rabbitfish present. It occurs at depths down to 40 m (130 ft) in lagoons, on reefs, and in seaweed and seagrass beds.