Leopard Coral Grouper (Plectropomus leopardus) are a heavily exploited, high value fish commonly found in the Asian live reef food fish trade. In past decades, many attempts at mass culture of various grouper species have been undertaken, however their small mouth gape at first feed has resulted in very low survival when using traditional live feeds such as rotifers. Use of wild caught or extensively cultured copepods has yielded potentially promising increases in survival and growth, but overall survival to the juvenile stage remains low making mass culture currently impractical.
The current study sought to build on past developments in grouper culture and recent advancements in copepod culture technology by observi ng how growth and survival were influenced by the addition of intensively cultured copepods to the early diet of P. leopardus larvae. Six tanks of larvae (n=3) , were fed either eggs and nauplii of the calanoid copepod Parvocalanus crassirostris , at a starting density of 5 mL-1, and the rotifer Brachionus rotundiformis , at a starting density of 10 mL-1, or were fed only B. rotundiformis , at a density of 15 mL-1, starting on the evening of 2 days post hatch and continuing until 9 days post hatch. After this initial period, all larvae were fed the same diet of rotifers, Artemia , and dry feed until the cessation of the trial at 21 days post hatch. Larvae fed P. crassirostris in addition to rotifers had significantly higher survival, 9.9% vs. 0.5%, than those fed only rotifers. Growth was also significantly enhanced in larvae offered copepods. Larvae fed rotifers were on average 1.5 mm shorter at 21 days post hatch than those that had been fed copepods. More rapid development and earlier onset of flexion were also noted in larvae that were offered copepods in their diet.
The use of intensively cultured copepods, in this study, increased survival tenfold over previous studies with P. leopardus larvae fed wild caught copepods. The application of intensively cultured copepods to the early diet of P. leopardus along with future research to evaluate late stage mortality issues may facilitate commercial production of this species.