A series of studies and experiments on the longevity of postlarvae of Penaeus indicus in flexible polyethelene containers with oxygen have indicated that a survival rate of 70% could be obtained at a packing density of 250 postlarvae (20 day old) per litre after 24 hours under oxygen packing. When the duration was increased to 36 and 48 hours 70% survival was obtained at 100 postlarvae per litre. However for the 8 day old postlarvae the same survival rate was obtained at packing densities of 300 and 150 postlarvae per litre for 24 and 36 hours respectively. Mortality of the postlarvae under oxygen packing has been attributed to cannibalism, accumulation of carbondioxide (indicated by the reduced pH) and increase in the ammonia.