Nets are generally long belt-shaped. According to the structure, it is divided into two types: non-sac and private single-sac. The upper and lower nets are equipped with floats and sinkers respectively. Most of the cysts with single-capsule structure are in the middle of the two wings, and some are on the side of the net. In order to prevent fish from jumping off the net and escaping during operation, some have installed net covers. In order to improve the efficiency of nets for catching bottom fish, some are equipped with a row of small pouches near the lower gang, called a hundred-bag net. In recent years, there have also been electrification in Xiagang to improve fishing efficiency. The ones used in rivers, lakes or reservoirs are mostly winged and single-sac-shaped, and their length depends on the ability of pulling and pulling the net and the area of ​​the water area. The height is 1.5-2 times the depth of the water, and it is used for fish farming in ponds, and its length is about 1.5-2 times the width of the pond. The height is 2-3 of the water depth. Both types of nets are used for coastal use, and their length is generally 100-500 meters. Net day length is 30-80mm Usually large nets are dragged and retracted by mechanical or animal power for many months, and small nets are mostly operated by manpower. The former works in rivers and lakes in the "winter in the cold zone", while the latter is also known as pulling nets in open water. When placing the nets, first place the nets into an arc-shaped encirclement, and gradually narrow the encirclement by dragging and pulling the clues at both ends of the nets. , until the net is pulled to the shore to collect the catch.