Abstract: Mud carp（Cirrhina mrigola）is one of major economic fishes in south of China because of its high commercial value for mandarin fish（Siniperca chuatsi）farming. In this study，we investigated the growth， water quality and biological structures of gastrointestinal food of mud carp two farming modes，to consider the value of manure fermentation in high-density culture of mud carp. The results showed that moderate manure fermentation can promote the growth of fish and make intestinal stuffed index increased. Feeding fermented manure can effectively reduce the water ammonia nitrogen concentration，suggesting that manure can be used as an organic carbon source regulating carbon/nitrogen balance and promoting heterotrophic bacteria growth. However，the total amount of suspended solids in pond increased significantly. The zooplankton Cladocera amount in treatment pond was significant higher than that in control pond. The number of phytoplankton algae also increased significantly. In manure pond， fish's intestinal contents showed a significant increase，fish intestinal protozoa and rotifers were significantly higher than that in control pond.