Penaeus monodon were collected from different hatcheries located on the east and west coasts of India from May to December 2002. From the east coast, 20 samples were collected from 10 hatcheries (2 tanks per hatchery), and on the west coast, 75 samples were collected from 12 hatcheries (6 to 7 tanks per hatchery). A minimum of 150 to 200 PL were collected from the 4 corners and center of each tank, which contained approximately 1000000 PL, and brought live to the laboratory in oxygenated bags. In addition, 107 samples of PL10 to PL20 submitted by farmers from different coastal states were included in the study.