1.The experiments will add three kinds of n-6 polyunsaturated fatty acid --Linoleic acid,γ-Linolenic acid and Arachidonic acid in different amounts from 0.5% to 3% to feedsfor rearing grass shrimp.During rearing perids, it will determine the average bodyweight , survival rate and feed efficiency in every 15 days of each ponds. Analyze fattyacid of shrimp muscles and feeds . IT also will analyze the Hemocyte and Bacteria ofshrimp and in attack experiment. So it will enhance shrimp disease resistence andincrease farmers economic profits.2.Our test is to realize the change of shrimp ponds water quality caused by rain, and theurgent influence it caused on shrimp. During the culture period, we generally usedcommon breeding ways, but when it is raining, we will start paddle wheels to add moredissolved oxygen content and putting lime to get steady pH value in treated ponds.Doing those above are hopefully to low down the influence caused by rain on shrimpand increase the survival rate of Penaeus monodon. In the test, we check the items ofthe water quality, Vibrio, growth and the healthy condition of shrimp, etc.