Ring-tailed cardinalfish (Ostorhinchus aureus)

Latin name

Ostorhinchus aureus

Other name

Ostorhinchus aureus

Identification

Ring-tailed cardinalfish have the following characteristics: they have 14 vertebrae; porous lateral line scales, 25; predorsal scales, 5; circumpeduncular scales, 12; total gill rakers, 24; developed gill rakers, 21; mouth large and oblique. 

Ring-tailed cardinalfish have black-pigmented intestinal mucosa that apparently hides the glow of bioluminescent prey from predators. Their eyes transmit ultraviolet light, which may aid them in their nocturnal foraging.

Features of fish fins

Dorsal spines (total): 8; Dorsal soft rays (total): 9; Anal spines: 2; Anal soft rays: 8.

Fish colouring

This fish is copper brown in color with a broad blackish band at the base of the tail. There is a narrow blue stripe on the upper jaw and a broad blackish stripe running from the front of the snout to the eyes. It is easily confused with Ostorhinchus fleurieu which the black band on the tail does not narrow in the middle, but unlike this species, the band is present in juveniles.

Distribution

Widespread in the Indo-West Pacific: Red Sea and East Africa to Papua New Guinea, north to Miyakejima, Japan, south to Australia and New Caledonia.

Habitat

A tropical marine species found in depths ranging from 1 to 40 m. Replenishment of this species at any coral reef site is usually by migration of adults and juveniles through sand and coral debris.

Size

Males of this species reach a maximum length of 14.5 cm. 

Behavior

It inhabits burrows in rocks or under ledges in shallow water. It is known to occur in mixed communities with Ostorhinchus apogonoides in summer and fall, but forms separate aggregations in winter and spring. 

Food and feeding habits

A nocturnal predator. Where algae are adjacent to its reef, it tends to go further than some other members of the family. Studies of stomach contents show that it is a generalist predator, feeding mainly on planktonic and benthic crustaceans, but, unusually for its family, it may occasionally feed on seaweed.

Reproduction

Ring-tailed cardinalfish exhibit clear mating during courtship and spawning.

Fishing

This species is of little commercial interest. It is mainly harvested for sale to the aquarium trade.

Relationship with a person

Harmless.