According to the feeding characteristics of different aquatic animals, such as benthic animals such as river crabs, they are accustomed to finding food at the bottom of the water, and adopt a slower feeding method, so that the required feed pellets should not be too hard and too strong, and the feed should be minimized. Loss caused by fine debris during biting. From this point of view, the puffed feed is more suitable: the puffed and granulated feed is easy to absorb and soften, suitable for foraging, and can also reduce the loss of debris generated during foraging, reduce feed waste and water pollution. Moreover, the expanded feed has a long water resistance and a high degree of ripening. Twin-screw wet extruders are commonly used to produce expanded feed. There are many factors affecting the expansion of materials, but they are mainly related to the conditions of quenching and tempering, the operating conditions of the extruder and the material properties. Changing the extrusion conditions can control the uplift of the extruded feed.