In October, in the late autumn, the pond carried the highest number of fish in the whole year. With the decrease of temperature, the temperature difference between day and night is large, and the vertical exchange of water layers is frequent, which can easily lead to abrupt changes in algal phase and cause hypoxia flood ponds. When harvesting and fishing, all farms should pay attention to gentle operation in the links of netting, sorting and disinfection and transportation of fish bodies to avoid secondary infection caused by mechanical damage to fish bodies. Before the aquatic products are listed, it is necessary to pay attention to the drug suspension period to ensure that the listed aquatic products comply with the relevant regulations of national food safety. The use of all kinds of prohibited drugs is prohibited to ensure quality and safety. According to the epidemic trend and recent disease characteristics of Ningxia over the years, the prediction and forecast of the aquaculture disease in Ningxia in October 2021 is as follows:
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1. Bacterial diseases: susceptible to columnar xanthobacterium disease, bacterial enteritis, bacterial sepsis, printing disease, erythroderma and furunculosis. The area of concern is high-density farms.
2. Parasitic diseases: susceptible to parasitic diseases such as rotidiums, ringworms and anchorhead bream. The area of concern is the farms in Ningxia.
3. Non-pathogenic diseases: prone to hepatobiliary syndrome, the area of concern is Ningxia farms; Ningxia farms pay attention to the prevention of hypoxia caused by pantang.
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(1) Preventive measures
1. At the end of the growth of farmed fish, water quality should be adjusted according to the change of the amount of fish carried in the pond; when the transparency of the water body is less than 30cm, it is necessary to fill new water in a timely manner, maintain a water level of 1.5m to 2.0m, use chlorine disinfectant to disinfect the water body after water change, fully disinfect the aquaculture water body once every 15 days, and use micro-ecological preparations to adjust the water quality. Appropriately extend the oxygenation time, ensure that the aquaculture water body contains sufficient dissolved oxygen, and avoid the occurrence of flood ponds due to lack of oxygen floating heads.
2. Ponds that need to overwinter should strengthen autumn cultivation, scientifically control the amount of bait feeding, and increase the feeding of companion bait containing VC and VE every 15 days, once a day, for 3 consecutive days, which can enhance the immunity of the fish body, improve the fat fullness of the fish body, and ensure the survival rate of overwintering fish.
3. The overwintering pond after the pond should be sprinkled with chlorine disinfectant at a concentration of 0.1mg/L, which can prevent and treat most bacterial diseases.
4. Strengthen daily management, patrol the pond in the morning and evening, pay attention to observing the water quality and the activities of fish farming, feeding, etc., and diagnose and treat the situation of outliers, swimming imbalance, abnormal feeding, and black body color in advance, so as to prevent the spread of diseases and reduce economic losses.
(2) Therapeutic measures
1. Columnar xanthobacterium disease can be used for thick glutaraldehyde, according to the product instructions, the whole tank is sprinkled twice. It can also be accompanied by oral flufrenicol (Note: It is forbidden to sell commercial fish during the drug break period), and feed it in sufficient quantities according to the product instructions.
2. Bacterial enteritis, erythroderma and bacterial sepsis can be treated with enrofloxacin (remarks: commercial fish are prohibited during the drug break period), 2 times a day per kilogram of fish body, the amount of bait feeding (100g: 10g) is 0.3g, and the continuous use is 3d to 5d.
3. Wheelworm and ringworm disease can be sprinkled in the whole tank with a combination of copper sulfate and ferrous sulfate (5:2).
4. Anchorhead bream can be sprinkled with 0.3mg/kg ~0.5mg/kg of crystalline enemy insects in the whole pool, repeat once after 7 days, and then use it in full amount once after 15d, the number of days between each time depends on the water temperature, when the water temperature is high, the number of days of interval is small, and vice versa.
5. Hepatobiliary syndrome can be fed with a mixture of betaine (30% content) 4g, rhubarb 4g, astragalus 5g, and 5g of macrophylla per kilogram of feed, and the treatment course is 10d to 15d.
6. Print the disease can use iodine-containing disinfectant, according to the product instructions, the full amount of the whole pool spilled, continuous use 2 times.
Source: Ningxia Hui Autonomous Region Aquatic Technology Extension Station