THE RATIONAL DESIGN OF POND FIDH CULTURE WITH REFERENCE TO THE PRINCIPLES OF YIELD INCREASE Ⅳ.SYSTEMATIC PREVENTION AND CURE OF INFECTIOUS DISEASES OF GRASS CARP.

A two-year pond culture experiment was conducted during 1987 1989.Additional experiments were conducted in 1988.The results suggested that the grass carp fingerlings that have been densely cultured should be dispersed in late summer or early autumn.Feeding should be continued in winter in order to keep the fish in good conditions after winter.The traditional stocking ratio of one grass carp to three silver carp and bighead should be changed to 1.5 2.5∶1.Green feed and formulated diets should be administered in proper proportions,and no fertilization should be provided.The new technique in creased the yield and economic efficiency,with a survival rate of over 80%.