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Nursery pond size ranges from 500 to 2000 m2 and water depth at 40-70 cm. The nursery pond should have at least one gate installed with a fine screen (1 mm mesh size) to prevent predators and competitors from entering. PL9-PLl0 are suitable sizes for stocking in the nursery ponds. Stocking density is 100-150 individuals per square meter. Prior to stocking, the pond should be completely drained and dried until soil cracks. ln cases where the pond cannot be completely drained, derris root (Rotinone) may be applied at 20 kg/ha to eradicate predators. Derris root is crushed until it breaks, soaked on water overnight and the resulting milky solution applied. Fertilizers are applied at 1000 kg/ha and 50 kg/ha for organic (chicken manure) and inorganic (Ammonium sulphate) fertilizers, respectively. Water exchange depends upon the time of spring tide when water can enter the pond. Chopped mussel or cockle meat are fed to the larvae at the rate of 10% of the total biomass. The culture period lasts 30-45 days when larvae becomes PL40 or PL60 (Kungvankij et al., 1986). |