The Muyang FAMSUN SJPS215B single screw aquatic extruder produces sinking crab feed and floating fish feed for the four major Chinese carp species. With the help of the density control system, the production of sinking extruded crab feed is smooth with the degree of vacuum being surpassing -0.05MPa. With the degree of vacuum being controlled by the valve, the volume weight of the crab feed can reach beyond 730g/L.