Pollution-free Penaeus vannamei for freshwater aquaculture

First, the desalination treatment Purchasing shrimp from the nursery, the emergence of salinity between 2 to 5 parts per thousand, before they can be purchased. The survival rate of shrimp directly into fresh water is very low, and it is necessary to carry out secondary depigmentation. This is the basic condition for ensuring the success of freshwater culture of Penaeus vannamei.
Before the release of seedlings, a thin film is used to enclose a certain area in the pond. Generally, the area of ​​0.1 mu per mu can be used, and the water depth is about 50 cm. Then use salt brine or coarse salt to adjust the water to a salinity similar to that of the nursery. According to our practice, 50 kg of coarse salt is adjusted for each acre of water, and then the shrimps are put into temporary stocking.
Second, feeding and management
1, clear pond disinfection and fertilization water quality is generally dry pond 10 to 15 cm depth 200 kg of lime per acre, with water 1 meter per acre depth lime 150 kg, 7 to 10 days after the water 30 to 60 cm. When entering the water, use a 40-mesh filter to prevent enemy creatures and wild fish from entering the pool. Then use fermented chicken, pig manure, etc. to fertilize the water quality and cultivate food organisms. Use 100 to 150 kilograms of fermented livestock and poultry manure per acre to grow the pool water into yellow, oil green, tea brown, with a transparency of 25 to 35 centimeters, so that the shrimp seedlings have ample natural food organisms after entering the pond.
2. The water temperature of holding management shrimp stocks is basically stable at 20 degrees Celsius, and low water temperature will affect the survival rate of shrimp seedlings. After the shrimps are stocked, they can be fed. Every 100,000 shrimps are mixed with an egg, a tablespoon of milk powder and a little salt. After adding water, stir and steam. Dilute with a 40-mesh sieve in the water and rinse. The entire pool is sprinkled and fed, feeding 4 to 5 times a day. After 4 to 5 days, soymilk and fish paste are fed, which can also be fed with special feed for shrimp seedlings. They are fed 4 to 5 times a day. Each 10,000 shrimp larvae are fed 5 to 10 grams, and the specific feeding amount is also It should be based on the amount of food and water quality of the shrimp. After about 15 days of storage, when the specifications reach 3 cm, the salinity is basically the same as that of the large pool, the plastic film can be pulled open, the soil can be cut open, and the holding pool and the large pool can be connected, and the shrimp seedlings can gradually enter. Dachi Yangcheng, the general survival rate of about 60 percent. In the initial stage of raising the shrimp, add 3 to 5 cm of water to the pool every day to gradually reduce the salinity. When the water depth reaches 0.8 to 1 meter, change the water in two to three days. 10 to 15 cm each time. In the process of conversion, water quality management is extremely important due to its high density and small water body. It is necessary to carefully observe changes in water quality, increase oxygen in time, maintain high dissolved oxygen levels, and remove residual baits in time. If you need to move to other pools, you should choose sunny and windless weather. Pull out the net in the morning. The operation should be light and the operation with water must be carried out. The temperature difference, water quality, and dissolved oxygen in the two pools must be similar to ensure the survival rate.
3, shrimp stocking time and density stocking time is generally from mid-May to mid-July. The first is nesting, generally 1 to 15,000 larvae per acre, yield about 75 kilograms; the second is intensive breeding, within an area of ​​10 acres, generally 6 to 80,000 larvae per acre, yield 300 to 400 kilograms, Requires the stocking of healthy shrimp. The size of the shrimp should reach 1 cm when stocking. In order to prolong the growth period, it is also possible to adopt the technique of holding seedlings in the early seedlings, thereby increasing the specifications and correspondingly increasing the yield. Even two crops can be cultivated in one year.
4, feeding
(1) Feed type: Penaeus vannamei is a food-eating shrimp, which is mainly plankton and benthic organisms. During the cultivation, in addition to artificially feeding fresh fish and shrimp to ensure the rapid growth of shrimp, In addition to bean cakes and peanut cakes, it is best to feed high-quality special-purpose granulated feed. The protein content of artificial compound feed should reach 35 percent or more, 4 percent of fat content, 15 to 25 percent of polysaccharides and low sugar content. Such feeds can be fed for 70 to 80 days, and individual specifications can reach about 15 grams.
(2) Feeding time and quantity: Feed feeding requires a small number of times. White shrimp in South America has a large food intake, strong activity, and short stomach time. Therefore, the number of daily feedings should be maintained 3 to 5 times. The time and frequency of feeding South American white prawn can be divided into two periods: early breeding, 8 o'clock in the morning and 7 o'clock in the afternoon; breeding in the middle three times, 8 o'clock in the morning, 7 o'clock in the afternoon and 11 o'clock in the night; At 7 o'clock in the morning, 12 o'clock in the afternoon, 7 o'clock in the afternoon, and 12 o'clock in the evening. Feeding amount, the early 3 cm shrimp seedlings can be fed 8 to 9 percent of the body weight of the shrimp, and the middle 3 to 8 cm shrimp seedlings can be fed 6 to 6 percent of the body weight of the shrimps. 8. The daily feed rate of shrimps above 8 cm in the rearing period can be 4 to 5 percent of the body weight of shrimps. The feeding method is evenly splashed on the edge of the pond. Penaeus vannamei has nocturnal habits, frequent activities at night, and strong food intake, so feed less during the day and feed more at night, from 30 to 35 percent of the total during the day and 65 to 70 percent at night. Seedling period should be uniformly fed to the whole pool, 3 cm along the pool evenly fed around. In order to effectively control the amount of bait, several bait trays can be set in the pool. After two hours of feeding, the inspection will be carried out. If basic eating is finished, it means that the amount of bait is basically the same, if there are still bait after 3 hours. It indicates that the amount of feeding is too large and can be adjusted as appropriate. The aerator should be stopped when feeding. At the same time, we must also pay attention to the bait size and palatability, otherwise it will result in the waste of food. Shrimp in the shelling can be fed as little as possible, after the oyster shell increased. In the middle and late stages of the culture of South American white prawn, fresh animal feed such as fish and snails can be fed two to three times a week. In particular, fresh animal feed should be added before catching, and animal feeds must be fed. Ensure that it is fresh and disease-free, and it must be fed after washing and disinfection.
Third, water quality management The first stage of cultivation is mainly fertilizer and water, so as to increase the natural food organisms in the water body, the transparency requirements in the middle and later stages are larger and are controlled at 30 to 40 cm. Dissolved oxygen should be maintained at more than 5 milligrams per liter and more than 3 milligrams per liter of the bottom layer. For water quality adjustment, the first stage is mainly adding water, generally not changing the water, adding water once every 3 to 5 days, changing the amount of water 5 to 10 centimeters each in the middle and late period, but not more than one fifth at a time, changing the amount of water should not be too large. Change the water as little as possible, or change the water several times.
During the cultivation period, quicklime is used regularly to adjust the pH and improve the quality of the bottom soil. It should be used once every 20 days, at a rate of 10 to 15 kilograms per acre, and should not be used during the oyster shell period. And regularly use environmentally friendly disinfectants, photosynthetic bacteria and other micro-ecological agents, disinfecting the body of water. Aquaculture ponds should be equipped with aerators, the use of aerators, early general noon boot for two hours, two to four hours before dawn, and then you can gradually increase the boot time, the middle and late high-yield Tangkou should be able to achieve almost continuous boot day and night. In addition, the ammonia nitrogen content of the water should be controlled below 0.2 milligrams per litre, and the concentration of hydrogen sulfide should be controlled below 0.1 milligrams per litre.

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