Sea chubs or ruddefishes are primarily tropical, schooling, herbivorous, coastal reef fishes comprising 4 genera and 11 species. They have a medium, often silver, moderately deep and compressed body with a small head and short snout. Chubs often congregate in great numbers to spawn. Juveniles frequently occur offshore around drifting debris and algae. In some areas in the world chubs are important food fish. In others, they are considered unpalatable. Chubs have no value to the aquarium trade and are not aquacultured.

Chub species – Kyphosus sp.  (June 2011)

Chubs are common in Hawaiian coastal waters and spawn throughout the year. Several Kyphosus species were reared in 2011-2015 from eggs collected in neuston net tows.

Adult Chubs (Kyphosus sp.) schooling in the shallows off Lord Howe Island.
Adult Chubs (Kyphosus sp.) schooling in the shallows off Lord Howe Island.

The eggs are pelagic, spherical and measure about 950 um in diameter. Multiple yellow pigment dots run along the embryo. Newly hatch kyphosid larvae measure 2.6 mm TL and have unpigmented eyes, undeveloped jaws, a large yolk-sac and a yellow pigment pattern along the body. They start feeding 3 days after hatching at 3.6 mm TL and can feed on large copepd nauplii and copepodites. Preflexion larvae have a yellow pigmented, elongated body and a straight gut. Postflexion larvae develop a darkly pigmented, moderately deep body and a coiled gut. Other features of the larvae include weak head spination, a small air bladder over foregut and a long pelagic juvenile phase. The larval period of this Kyphosid species is only about 20 days.

Chub (Kyphosus sp.) larvae reared in the laboratory.
Chub (Kyphosus sp.) larvae reared in the laboratory.

Chub larvae survive and grow very well on copepods throughout the rearing phase and have no special culture requirements. In fact, the larvae are probably easily raised on rotifers and Artemia sp.. The juveniles are not aggressive at high densities and grow fast on artificial diets. Based on the culture characteristics of the larvae and juveniles, chub species with good flesh quality could make ideal candidates for aquaculture.