Healthy juvenile P. monodon tested negative forwhite spot syndrome virus were obtained from a shrimp farm (South 24 Parganas, West Bengal, India). Shrimpswere acclimatized for 14 days and fedwith commercial diet (40% crude protein) three times daily before start of experiment. The experimentwas conducted in triplicate in FRP tanks (1000 L; bottom area 2 m2) filled with chlorine free brackishwater. Two hundred and fifty two P. monodon juveniles (2.9 ± 0.10 g) were randomly distributed in the four experimental groups at 21 nos. tank−1 following a completely randomized design (CRD).