At present, the water temperature and temperature gradually pick up, and the management of crab cultivation in April-May is an important part of the annual production of crabs. Based on my own practical experience, the author believes that the following aspects should be emphasized:
1. Control water level: In order to promote early feeding and early growth of the crabs, the pool water should be controlled at about 40cm when the weather is fine. Under the sunlight, the temperature of the water rises faster to facilitate the crab feeding. If a continuous rainy weather is encountered, it is necessary to deepen the water level appropriately so as to prevent a large change in the water environment in the pool and adversely affect the river crab.
2. Timely feeding: When the water temperature reaches 10°C, the crabs can feed properly when they start feeding. The amount of feeding is generally controlled at about 1% of the body weight of the crab. The bait is mainly concentrated, supplemented with 15% roughage. Mild feeds must not be fed.
3. Moss removal in time: In April-May, the water temperature is low, the water quality is lean, and it adapts to the growth of moss. If the moss grows in large quantities, it will be extremely unfavorable to the crab. You can use the following methods to clear:
1 When a small amount of moss appears, it can be manually removed or increased in depth and applied with bio-nutrition fertilizer to reduce the transparency of the water and achieve the effect of inhibiting the growth of moss.
2 If there is a large amount of moss, it is recommended to use the moss and other drugs to kill, but to avoid the shelling period of crabs. After the killing, "triadolytic toxin or crab cool" can be used to reduce the negative effects of toxins and drug residues on the crab.
4. Supplemental nutrients:
From the beginning of April to the end of April, the first shelling of the crabs was completed. At this time, the crabs were of weak constitution. It is recommended to use “calcium 90†or “amino acid calcium and phosphorus C†to directly sprinkling water. The content of calcium, phosphorus and other nutrients in the water body is critical to the growth of the crab. If it is not enough, the crab shells will not be able to harden, and soft shell disease or shelling will occur. In severe cases, the crab will die.
5. Do a good job of prevention and control of disease prevention from April:
1 Quanchiposa a disinfectant every two weeks or so to prevent germs from growing. Drugs are: strong chlorine, lime, bleach and so on.
Zinc sulfate compound was used to kill ciliates once in late 24th to early May.
In the month of March, a course of 5-7 days of internal medicine mixed feed is used; in May, it is also used once every two weeks.
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