After the saury catch is sucked on the vessel by the fish suction machine, it enters the sorting machine through the fish-water separator. The sorting machine is equipped with several rollers parallel to the sliding direction of the saury, so that the saury can slide on the inclined platform composed of several rollers. The saury is sorted and classified from small to large by the variable spacing between the rollers. The sorted fish are guided to the arranging machine, which uses image recognition technology to distinguish the direction of the head and tail of the fish, and classifies them according to the direction of the fish body for subsequent packing operations. In addition, most of the machine parts are made of stainless steel to avoid corrosion due to contact with sea water and salt at sea.