In winter, the temperature and water temperature gradually decline. How to properly manage the tilapia wintering culture has a direct impact on aquaculture efficiency. To this end, a tilapia overwintering aquaculture programme has been formulated with regard to the characteristics of this stage of cultivation, hoping to help farmers to increase efficiency and reduce unnecessary losses. Although there has been no large-scale freezing of tilapia in the past two years, it is more practical to ensure safe wintering during the current low fish price. It is necessary to strengthen overwintering management to ensure the benefits of tilapia breeding.
1. What are the differences in the winter culture of tilapia? What are the main causes of winter death?
A: The main difference between tilapia and other four major domestic fish is temperature. In general, Nile tilapia is below 7 degrees Celsius and Giflife tilapia is under 9 degrees Celsius. Less than 15 degrees Celsius, if coupled with poor water quality in the pond, it is prone to frostbite. In winter, there is a tendency for water body deterioration, especially for the bottom water body. In winter, when the air pressure is low, the temperature is often relatively low. Haze and fog conditions are prone to frostbite floating head frost damage.
Since the western part of Guangdong Province is located in the south of the Tropic of Cancer, it is a mild tropical and subtropical monsoon climate. During most of winter, the water temperature can ensure that tilapia can still feed and grow normally. Normally, the amount of feeding, the feeding method, and the usual change are not constant when there is no cold flow for a long time. After the temperature has dropped, the amount of feeding can be appropriately reduced. Feeding time should be controlled flexibly. When the temperature is low, the morning can be postponed to 9-10 and the feed can be fed to 4-5 in the afternoon, when the surface water temperature is lower than At 15°C, stop feeding.
2. To protect against the possible loss of tilapia breeding due to the continued low temperature in winter, it is necessary to prepare for the infrastructure of the pond. What measures will be taken to ensure that the cultivation of tilapia will not be lost during the cold wave attack?
A: The average annual temperature of the western part of Guangdong is about 23°C. However, when it encounters cold air, especially in continuous rainy and cold weather, the water temperature will drop below 12°C, and frostbite and frozen death of tilapia will occur. In view of the problems of temperature and winter frostbite in the winter of tilapia, we can start with pond construction and strengthening management. Choose the winter pond, the best depth is more than 2.8 meters (more than part of the area can also be), the best pond side can have more than 15 meters and 2 inches deep wells, if conditions permit, the current construction of artificial winter shed cost is about the first year 5000 yuan / mu, the second year 3000 yuan per mu cost.
Before the cold wave hit, pump the pool water to more than 2.8 meters, preferably when the water temperature of the water source is not reduced. If the water temperature of the water source has dropped, pump the bottom water of the water source to ensure that the water temperature of the water source is higher than the surface water temperature of the pond. When the surface water temperature is lower than 12°C, the well is pumped. The practice of farmers in Gaozhou is to play 3-4 simple deep-water wells around the pond and each well is more than 6 meters deep. (The method is to introduce a water pipe to the soil with a depth of 7-8 meters, which is economical, fast, and has a deep water level. High temperature characteristics, continuously pumping well water to fish ponds can raise the water temperature to around 16°C. It is very important to dig a drainage ditch around the overwintering fish ponds. This is a very important task because, when the cold wave continues southward, it often causes rain and cold weather. The rainwater is colder than the pond water. After digging the drainage ditch, the rainwater can be drained out of the pond. So that the water temperature in the pond remains stable. These soil methods have low costs and significant results and are worth promoting.
3. How do winter tilapia raise water, change bottom, and increase oxygen?
A: Since the water temperature in winter is relatively low, many people mistakenly believe that water quality cannot be adjusted or that there is no need to regulate the water body. In fact, this concept is very wrong. It is precisely water quality that has become the key link for the death of tilapia in winter. Frozen tilapia is not able to withstand the deterioration of the water quality at the bottom of the pond, and the fish is killed by rising up and breathing. Under the protection of the thermocline, the temperature at the bottom of the pond is generally 3 to 5 degrees Celsius higher or lower than the surface of the pond (Winter: High , Summer: Low) It is this 3-5 degrees Celsius that becomes the key to life and death. Wintering tilapia pond water quality regulation ammonia nitrogen, nitrite, hydrogen sulfide and other indicators recommended in December when sunny. The monitoring of the PH value is monitored at all times, and some anaerobic microecological preparations and physical adsorbents can be selected for improving the sediment quality. In addition, the algal blooms in the overwintering shed ponds are prone to cyanobacterial blooms. It is necessary to use moss algae net, copper sulfate, etc. in a timely manner. Overwinter pond oxygenation should be 3 to open, 1: the lack of oxygen floating head must be opened, 2: it must be open for rain and cold, 3: it must be open at noon on sunny days.
4, how to feed, strengthen nutrition, enhance physical fitness to make it safe winter?
A: Natural tilapia ponds generally do not eat in the winter, and nutrient deficiency can easily lead to a large number of dead fish after the winter. Natural tilapia pond tilapia is recommended to choose Ao tilapia, and it should be controlled within 0.3 kg/tail. Specifications are appropriate. In wintering sheds, tilapia can maintain 1% feed, and the frequency of feed changes is mainly based on changes in water temperature, usually once a day. In case of weather changes or low temperatures, feeding can be reduced or stopped. During the early winter period, liver protection and gallbladder medicines such as detoxification and heparin, Sanhuangsan, multi-dimensional enhanced fish constitution and immunity can be added to the feed.
5. What are the common diseases of tilapia culture in winter and how can it be prevented?
Answer: Tilapia eats little in winter and the weather is cold. There are few common bacteria and parasitic diseases. The major diseases are saprophytic disease, and prone to trichoderma and water quality deterioration in wintering sheds. , to reduce the continued infection of hydromycosis, forced to choose nylon mesh network should be moving network, after the completion of the net Quanchiposa 0.5-1PPM povidone iodine solution and anti-fungal drugs such as: gall, Sophora flavescens scattered, small Soda, salt and so on. The treatment of trichoderma disease is the same as conventional treatment. 0.4-0.5 PPM copper sulfate + ferrous sulfate can be disinfected with povidone iodine the next day. After finding or feeling frostbite in tilapia, measures should be taken immediately to deal with them, mainly including anti-stress immune enhancers (detoxification VC, glucose and the like) and disinfectants (mainly disinfectants capable of treating hydromycosis).
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