From July to July, high temperatures coupled with frequent rainfall increased fish and shrimp diseases in various aquaculture areas. From the beginning of June in Hainan tilapia, the onset of fish began to occur one after another. Sustained hyperthermia caused small fish mortality and the symptoms were not obvious. The farmers used the appropriate materials to control the high temperature period.
"Compared with previous years, the incidence of tilapia in Hainan is still relatively low this year." Hao Yongtao, head of sales of Hainan Xiangtai Fisheries Co., Ltd., said that under continuous high temperatures, tilapia began to develop in Hainan, mainly in 0.5-2 cases. Two / tail size fish. It is understood that 20% to 30% of small fish in the diseased pond currently have 10,000 deaths per day. However, judging from the entire production area in Hainan, the overall incidence of small fish is only about 20% for the time being, which is a significant drop from previous years.
According to Hao Yongtao's report, the problem fish concentrated as outliers, spins, turns, and died immediately. There was no obvious "stretching of the eyes and pimples in the jaw." The anatomical observation of the spleen was not dark and the liver was not swollen. , but people are still customarily referred to as streptococcus.
“Now the symptoms of streptococcal disease are not as obvious as before.†Fu Yunling, manager of the Hainan area of ​​Hainan Baolu Aquatic Technology Co., Ltd., reflected that the symptoms of sick fish are different from the previous “streptococcal diseaseâ€. There are also industry insiders believe that there may be a few years of development of animal bacterial diseases, new diseases have emerged.
"High temperature is only the cause of the disease." Fu Yunling believes that high temperature is one of the causes of the occurrence of tilapia, but the high density of seedlings is the root cause of the disease. Under normal circumstances, the 20g/tail size density is in the range of 23,000 to 30,000 tails/mu. If the farmers choose the upper density limit and do not do related water quality management work, the high temperature period is prone to water quality of ammonia nitrogen and ammonia. Nitrates are too high and cause dead fish. Therefore, farmers should open more aerators and pay attention to regulating the quality of fish ponds and sediments during high temperatures.
Many farmers in the current production area began to control their materials in order to reduce the incidence rate. However, Fu Yunling stated that farmers have generally realized that long-term high-strength material control will affect the overall quality of tilapia, so the control of materials is less than last year.
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