Feeding habits of hatchery-reared larvae of greater amberjack Seriola dumerili

To obtain basic knowledge on the feeding habits of greater amberjack Seriola dumerili larvae during the early phase of seed production, larvae were reared until 15-20 days post hatching. Larvae were fed on rotifers Brachionus plicatilis sp. complex with different body sizes, i.e., super small type, small type, and large type rotifers, and the survival rate, standard body length (SBL) and gut contents of the larvae were examined. There were no significant effects of rotifer size on survival and growth of greater amberjack larvae, except for the smallest SBL of larvae fed with super small type rotifers. The body sizes (lorica length and lorica width) of rotifers ingested by larvae did not change in accordance with the growth in larval body size and mouth size from the onset of feeding to ~ 7.6 mm SBL, despite the larvae having a chance to prey on larger body size rotifers in the tanks. Counting the number of rotifer eggs in the guts revealed that larvae ≥ 4.5 mm SBL appeared to selectively prey on egg-bearing rotifers, whose body sizes are relatively large among the rotifer populations in the tanks, indicating an ontogenic change in the feeding habit of greater amberjack larvae.