The Hawaii Larval Fish Project
Larval rearing of the schooling banner fish, Heniochus diphreutes
March 01, 2014
Family: Chaetodontidae > Genus: Heniochus > Species: H. diphreutes
Butterflyfishes are mostly small, conspicuously colorful reef fishes with deep, laterally compressed bodies and small mouths. The family comprises 130 species in 11 genera. They primarily fed on benthic invertebrates, especially coral polyps. The striking chromatic patterns make butterflyfishes very popular among marine aquarists; however, many species have specialized diets, such as stony coral polyps, and fare poorly in captivity, refusing to feed. Interestingly, wild collected, late-stage larvae of some of these species can be conditioned onto aquarium foods. Bottlenecks in adult spawning and larval rearing have kept butterflyfishes from being aquacultured.
The pennant fish (Heniochus diphreutes), schooling bannerfish, or false Moorish idol, was cultured from the egg to juvenile stage in the fall of 2013. This schooling, planktivorous butterflyfish species occurs from the Red and South Africa to Japan, Hawai‘i and Australia. It is one of the most suitable butterflyfish species for aquariums due to its bold demeanor and dietary habits. H. diphreutes eggs were collected in late August in Oahu’s coastal waters. The first-feeding larvae are elongate (2.6 mm TL), darkly pigmented and can capture 60 to 80-micron copepod nauplii. During flexion (20-25 dph), they become increasingly deep-bodied and ovoid in shape. At this stage the head becomes encased in armor (tholichthys plates), a specialization to pelagic life. From here on the larvae become more fragile and undergo critical periods of high mortality. The larval stage is long. The prolonged white forth-dorsal spine, characteristic of Heniochus species, starts to develop near 60 dph. The white body with black bands first becomes noticeable near 85 dph. Juvenile transformation is completed near 100 dph at about 18 mm TL. At this point the fish can feed on artemia nauplii and be transferred to juvenile grow-out.
Aquacultured butterflyfish would be a valuable addition to the aquarium hobby, especially since the juveniles of many of the difficult to keep species could be pre-adapted to feed on aquarium foods. Unfortunately, the long and complicated early life history of H. diphreutes and probably other butterflyfish species makes even experimental rearing a tremendous challenge. This is the first documented larval rearing of a butterflyfish species.