1, water salinity, the most suitable water salinity in the process of Penaeus vannamei culture is 15-20, and the salinity that fresh water can adapt to is at least 0.2; According to the salinity before and during seedling release, it is best to exceed 2 grids.
2. PH value of water body: The most suitable PH value of water body in the process of Penaeus vannamei culture is between 7.5 and 8.5. If it exceeds 9.0, it should be treated in time, otherwise it will cause algae proliferation and algae inversion.
3. The ammonia nitrogen value of water body is the best when the ammonia nitrogen value is 0 in the process of Penaeus vannamei culture; If the ammonia nitrogen value cannot exceed 0.5, it will cause nitrite, and in serious cases it will cause nitrite poisoning.
4. Nitrite in water. The value of nitrite in Penaeus vannamei water is the best when it is 0, and it is best not to exceed 0. 1. If nitrite exceeds 0. 1, nitrite poisoning will be formed, which will cause the symptoms of Penaeus vannamei stealing.
5. Total alkalinity in water: The total alkalinity in water should not be less than 75ppm in freshwater culture of Penaeus vannamei, not less than 200ppm in seawater culture, and the most suitable total alkalinity in aquaculture is between 75 and 200 ppm. The total alkalinity of the water body should be between 120- 150 ppm during the onset and rain of prawns.
6. The total hardness of water in the process of Penaeus vannamei culture is generally120-200mg/L..
7. Dissolved oxygen in water, the most suitable dissolved oxygen for Penaeus vannamei is between 5 mg/L and 8 mg/L, and shrimps below 2mg/L are prone to lack of oxygen, resulting in incomplete shelling; Above 10mg/L, the dissolved oxygen of shrimp is too high, which is easy to cause bubble disease.
8. Hydrogen sulfide in water. During the culture of Litopenaeus vannamei, the hydrogen sulfide in the water should not exceed 0. 1mg/L, which will increase the toxicity of hydrogen sulfide in the water and cause shrimp poisoning.
9. Water temperature, the most suitable temperature in the process of Penaeus vannamei culture is 22-28 degrees; When the temperature is lower than 18℃, the growth of Penaeus vannamei is slow and difficult to grow. When the temperature is higher than 33 degrees, the resistance of Penaeus vannamei decreases, which is easy to cause disease problems.
10, water transparency, the most suitable transparency of Penaeus vannamei in the process of culture is 25-40 cm, and the water with transparency above 60 cm is thin, so water and fertilizer can't get up. When the transparency is less than 20 cm, the water quality will age and harmful toxins will increase, resulting in shrimp poisoning and even death from stealing.
Extended data:
Preparation and management techniques of Penaeus vannamei pond in greenhouse in spring and autumn;
1, basic requirements for ponds
First of all, the depth of the pond needs to meet the specified requirements. Usually, the depth of the pond is about 1.8 m ... Secondly, it is necessary to ensure that the pond has a perfect water supply and drainage system and can realize rapid water change operation.
Thirdly, it is necessary to ensure that the pond can get enough water, and the nutrients in the water can meet the breeding needs of Penaeus vannamei. Fourthly, add oxygen-increasing equipment with fixed power in the pond, supply oxygen to the pond within a specified time, and improve the dissolved oxygen content in the pond.
2. Main framework of greenhouse
Combined with the actual greenhouse construction and the needs of Penaeus vannamei breeding, the greenhouse framework should meet the following requirements: First, the greenhouse structure is mainly herringbone, which can reduce the construction difficulty, save building materials and reduce the greenhouse construction cost.
Secondly, a bamboo frame structure can be used. This structure not only meets the actual needs in strength, but also is easy to disassemble after construction. The bamboo and wood frame can be recycled and the cost is low. Thirdly, the covered plastic film should be mainly 0.6-0.8 mm, with white color and good light transmittance.
3. Preparation for pond disinfection before stocking shrimp seedlings.
Considering the growth characteristics of Penaeus vannamei and the sanitation and flora environment in the pond after the establishment of the culture greenhouse, it is necessary to disinfect the pond before releasing the shrimp seedlings.
Specifically, quicklime should be added to the pond for disinfection 25 days before the shrimp seedlings are officially stocked. After the quicklime is disinfected, a certain proportion of bleaching powder should be added to the pond one week in advance, and aquaculture water and fertilizer can be added appropriately.
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