The effect of salinity on the survival and growth of Penaeus monodon (Fabricius), P. semisulcatus (de Haan), P. merguiensis (de Haan) postlarvae was examined. Postlarvae P15 were gradually acciimatcd to the desired salinity before starting the experiments. Minced tuna or lizard fish meat given at a rate of 100% body weight was used as feed. High survival of P. monodon was obtained at 30 ppt salinity; however, growth was faster at 10 ppt. On the other hand, with P. sem;sulcatus, growth and survival rates were higher at 30 ppt. Survival rates for P. marquiensis and M. etuis were the same at the salinity ranges of 10 to ^5 ppt and 10 to 30 ppt, respectively, although lower salinities apparently favored faster growth. With P. japonicus, growth was essentially similar at 10 to 25 ppt; however, survival rates were higher at 20 and 25 ppt.
Tolerance of P. monodon, P. semisulcatus, P. merquiensis P japonicus, M. ensis and M. endeavourr to sudden changes in salinity was also examined. Post larvae were held at a given salinity and transferred to salinities higher or lower than the initial salinity. Results showed wide salinity tolerance of all species examined.
Preliminary studies on the effect of temperature-salinity combination on P. monodon postlarvae were also conducted. Post- fervae were subjected to three temperatures: 21-23°C, 25-30°C and 33-35°C and three salinity levels: 10, 20 and 30 ppt. Results suggest that both salinity and temperature interact to affect growth and survival of P. monodon. A combination of low to intermediate temperature and intermediate to high salinity gave higher survival; however, low salinity-high temperature combination favored faster growth.