Slender Cardinalfish

Rhabdamia gracilis is a species of cardinalfishes native to the Indian and Pacific Oceans.

Description

An almost transparent cardinalfish with a silvery head and abdomen, a black tip on one or both caudal-fin lobes, a bluish mid-lateral stripe, and a reddish patch on the gill cover behind the eye. Females larger than 4 cm SL have one or two dark stripes/spots along the sides, which are absent in males and smaller females.

Dorsal spines (total): 7; Dorsal soft rays (total): 9; Anal spines: 2; Anal soft rays: 12 - 13. This species is distinguished by the following characters: bluish longitudinal stripe on the middle of the body; translucent white or pink, silvery on head and abdomen; caudal peduncle sometimes with a posteriorly placed black spot; characterized further by one or both caudal fin lobes having black tip; greatest depth of body 3.3-3.6 in SL.

Distribution

Houtman Abrolhos Islands, and offshore reefs of north Western Australia, and Ashmore and Cartier Islands in the Timor Sea, to Sydney, New South Wales; also Cocos (Keeling) Islands in the eastern Indian Ocean. Elsewhere the species occurs in the tropical, Indo-west-central Pacific, from East Africa to the Marshall Islands, and north to Japan. Forms large dense schools in gutters and above the reef.

Habitat

Forms large schools in coral reefs and rocky areas. Feeds on plankton above the reef during the day and at night.