Sinking syndrome of larvae of the leopard coral grouper, Plectropomus leopardus, and its control for large-scale larviculture

We investigated the sinking syndrome of larvae of the leopard coral grouper Plectropomus leopardus in a small-scale experiment, and designed and constructed a rearing system to prevent sinking syndrome in large-scale larviculture, using a water pump to agitate the water at the bottom of the rearing tank. Sinking syndrome was observed in 3 dph (days post hatching) larvae and the number of dead larvae, which sank to the tank bottom, increased during subsequent nights. After three mass scale production trials of the sinking prevention system, final survival rates ranged from 13.0 to 30.0% (mean 20.3%). A total of 340, 000 juveniles of mean total length 30.0-31.2 mm were harvested at 55-60 dph. Application of this system to the rearing of leopard coral groupers dramatically improved productivity and stabilized survival rates compared to conventional methods.