The Hawaii Larval Fish Project
Larval rearing of the Hawaiian spotted boxfish, Ostracion meleagris
August 01, 2014
Family: Ostraciidae > Genus: Ostracion > Species: O. meleagris
Boxfishes and cowfishes are small fishes with a triangular, rigid, armored body encased by fused scales. The family comprises 33 species in 12 genera. Spiny species are referred to as cowfishes and smooth species as boxfishes. Boxfish and cowfishes can be quite colorful and have loads of personality for the aquarium but may release a toxin that can kill all aquarium residents.
Spotted boxfish (Ostracion meleagris) were reared in April and May of 2014 from wild collected eggs at the Reef Culture Technologies hatchery. This species is fairly common on Hawaiian reefs where it primarily feeds on tunicates, sponges and algae. Males are attractive with dark blue black-spotted sides and a brown white-spotted dorsal back. This fish has a reputation for being difficult to keep in aquariums and will release ostracitoxin when stressed. Boxfishes and cowfishes are not aquacultured.
O. meleagris eggs are slightly oval, contain a cluster of yellowish oil globules and measure about 1.5 mm in diameter. Hatching occurs after 3-4 days. The bulbous, dark pigmented larvae measure about 2.1 mm at hatching. They start feeding after about 4 days, undergo flexion between 10-15 dph and start juvenile transition by 30 dph. Live feeds during the larval phase consisted of copepods and newly hatched artemia. 40 dph juveniles readily feed on live artemia and frozen foods. The larvae are easy to raise.
Interestingly, stressed or dead 90 dph O. meleagris boxfish juveniles do not release toxin. It appears that this species - like the cultured juvenile cowfish reported on in February - does not develop the ostracitoxin-producing bacteria (Vibrio sp.) when raised from eggs in captivity. Captive breeding boxfishes and cowfishes without toxin is a big step toward making these unique fishes more suitable for aquariums.