In theory, crabs must be shelled in shallow water. Especially in the crab phase, the clam shell has a high frequency and consumes large amounts of oxygen. Therefore, a shallow water environment with good water quality and good dissolved oxygen must be required. Using the same batch of crab seedlings, different water depth tests were conducted under the same conditions of water quality, density, and bait. The optimum water layer for crabs in the crab cultivation phase was 10-30 cm, and 80 cm or more, while crabs were not shelled. All died. However, in the production, the pond water level is too shallow, the water temperature and water quality are easily mutated, and it is not conducive to the survival of the crabs. Therefore, in order to stabilize water quality, the average depth of water in the crab pond should be kept between 50 and 80 cm. At the same time, aquatic plants (submerged plants and floating plants) should be planted in the pond to artificially create a shallow water environment for the crabs to inhabit, grow and clamshell. In addition, the water level should be deepened before the next storm to prevent sudden changes in water quality. Face Mask Machine,Pm2.5 Mask Machine,Filter Mask Machine,Filter Cotton Making Machine Dongguan Huitong Automatic Machinery Technology Co., Ltd , https://www.medicalmaskmachines.com