Tilapia is a tropical fish. It is not tolerant to low temperatures. The water temperature for living and growing ranges from 16°C to 40°C, and the optimum temperature is 28~32°C. When the water temperature drops below 12°C, it will gradually die. Under normal conditions, tilapia winter winter must be adopted when the water temperature drops to 16°C to ensure the smooth wintering of tilapia. There are many wintering methods for tilapia, and depending on the climate and wintering conditions, there are mainly covered winter greenhouses, hot springs, deep wells, waste heat, boiler heating, and electric heating. The key to the wintering of tilapia is to grasp the time of wintering in the pond, disinfection of fish ponds, stocking density, adjustment of water quality and water temperature, feeding and management, and disease prevention and control techniques.
One, before wintering
1. Requirements for Overwintering Fishes Before wintering in the wintering season, the fortification institute will raise fish to concentrate in the special pool for the winter and carry out strengthening and cultivation to promote the growth of the barnyardgrass, enhance the ability to withstand cold in winter, and gradually adapt to the living environment during the winter. Some of the weak or injured fish were eliminated in advance.
The selection of the overwintering fish shall be selected from the fish species cultivated in the special pool for autumn seedlings, and the overwintering species shall be 5-6 cm in total length, so that the utilization rate of the wintering pond will be reduced as a result of the assembly, and the fish species that are too small will be overwintering. In the process, poor adaptability, low survival rate, and the phenomenon of varying sizes of overwinter seedlings in the same pond occur. The wintering time of common seedlings requires that the specifications should be neat when entering the pond. Tilapia breeds several times a year. The specifications of the fish when the fish enters the pool are uneven, and it is inevitable that they will appear to be small bullies, and stunted or even die.
Therefore, when the fish species enter the pool, they must be screened, and enter the pool according to the size and size, so as to manage and increase the survival rate. The selected fish species should also be selected as individuals with robust physique, no injury, no disease, smooth surface, and no frostbite.
When choosing to stay, the operation must be light and meticulous, so as not to damage the fish body, and to enter the pool immediately upon selection. The fish species should not be concentrated in the pool for a long time during grading and screening. Generally, two hours after suspending water in the net pool, the fish should be divided into sieves and counted into the pond. The longest time should not exceed five hours, and it is even more unfavorable. Density of long-distance transportation, otherwise it will cause severe fish injuries, resulting in low survival rate overwintering.
2. Preparation of overwintering facilities According to different wintering methods, the equipment for heating, aeration, and sewerage required during wintering should be ready before winter, such as heaters, boilers, temperature controllers, water pumps, aerators, etc. , and pre-repair all overwintering equipment. When a farmer conducts a small area over the winter, one to two 3 kilowatt electric heaters should be used for every 30 cubic meters of water. Treat fish ponds, pipelines and channels first with quicklime, bleaching powder or other disinfectant before the winter, which is consistent with the treatment of pond cultured fish.
3. When the fish body is disinfected before winter, the broodstock and fish species have different degrees of damage during transportation and operation. Before the pool enters the pond, the fish body should be disinfected with drugs, and 2%~3% salt solution can be used (no iodine is added. ) Soak the fish for 5 to 10 minutes, depending on the tolerance of the fish. After all the fish have been put into the pond, 0.3ppm of chlorine dioxide can be used to disinfect the whole pond to prevent disease. Within one week after entering the pond, it is necessary to pay close attention to the activities of the fish species in the pond, especially if the wounds of fish fingerlings operated at low water temperatures are infected, and take corresponding measures in time. A week after entering the pond, the fish species were basically stable and entered the wintering period.
Second, the time of wintering fish into the pool and its precautions
1. The time for the wintering fish to enter into the pool during the time of entering into the pond should be controlled when the water temperature drops to 18~20°C. The specific pooling time varies with the climate in different places. However, it is necessary to enter the overwintering pool when the water temperature is above 18°C, and it must be completed before the first cold current. If the water temperature is lower than 16°C, the catching fish cannot be used for wintering, because the fish body has frostbite and enters the pond. Will continue to die. Fishing overwintering fish should choose wind and sunny weather, so as to avoid fish frostbite.
2. The density of alfalfa, the density of overwintering fish into the pond, depends on the wintering pond's environmental conditions, fish size and management level. The temperature of the flow pool is lean and the dissolved oxygen is sufficient. Generally, 12-20kg of broodstock or 8~12.5kg of fish can be released per cubic meter of water. Ordinary water aquifers can hold 5~7.5kg of broodstock per cubic meter of water. Breed 3.5 ~ 5kg; static pool, can regularly change the water, per cubic meter of water body can be placed broodstock 2.5 ~ 4kg, or 2 ~ 3kg fish species.
Third, the management points during wintering
The wintering period of tilapia is relatively long. During the whole winter period, special personnel are responsible for the management of water temperature, water quality regulation, rational feeding, and prevention and treatment of fish diseases.
1. Water temperature control Overwintering fish can control the water temperature at 20~25°C within 10 days after entering the pool, which is beneficial to the healing of light wounds, inhibiting the occurrence of watery mildew, and increasing the survival rate of overwintering. After the situation is basically stable, the water temperature should be kept above 16°C throughout the winter, and the water temperature should generally be controlled between 18°C ​​and 20°C. Should prevent sudden changes in water temperature, but also should prevent the water temperature below the lethal temperature, nor long-term control at 20 °C above, long-term high temperature is not conducive to winter management, but also increase feed input, because the water temperature is higher, the fish's vitality Stronger, more physical exertion, a corresponding increase in food intake, resulting in increased excreta, not only consumes a lot of oxygen in the water, but also produce a variety of substances that are detrimental to fish.
The use of warm water over winter, such as hot spring water, factory cooling water, etc., can adjust the flow of water to control the water temperature; use of steam heating overwinter, can adjust the steam discharge to control the water temperature; use deep well water over winter, increase the water change Number of times to maintain a certain water temperature; plastic film greenhouses, sunny days, use of solar energy to increase temperature, at night or in case of cold, electric heaters to increase temperature.
2. Water quality regulation The wintering pool should keep the water quality fresh. During the wintering period, water quality analysis should be performed frequently. Attention should be paid to observing the floating head of the fish, and oxygenation measures should be taken in time. The dissolved amount should be kept above 4 mg/L. When the indoor temperature is lower than the water temperature, in order to reduce the water temperature drop due to water evaporation, an air compressor should be used to increase oxygen through sand filter stones. When the temperature is higher than the water temperature, a water wheel type or impeller type aerator can be used to increase oxygen, but the boot time should not be too long, usually 20 minutes. Warm water overwintering pool can regulate water quality through water flow. Plastic film greenhouses, due to the difficulty of changing water, generally do not change the water, only when the water quality is too strong, the fish floating head is more serious when adding some new water or through the oxygen to regulate water quality. Indoor static water overwintering pool, in the 10 days after entering the pond, the overwintering fish, due to a lot of waste, should be a day of suction, after the week should be dirty suction or flushing 1 or 2 times. At the same time, it is necessary to change the water once in the early days and change the water every 3 to 5 days afterwards. In order to prevent the overwintering pool water temperature from changing too much, the amount of water to be changed each time should not be too much, generally controlled at 1/3~1/4. Before the water change, discharge the residue and feces, and then inject new water. The temperature difference of the pool water before and after changing the water is preferably within 2°C. If the water quality in the overwintering pool deteriorates, the fish floating head is serious, and it is impossible to replace the new water with proper temperature in time, it can be treated with hydrogen peroxide. The method is to relieve severe floating heads by sprinkling 0.5 kg of 30% hydrogen peroxide in 10 cubic meters of water.
3. Feeding tilapia in feeds consumes a large amount of energy during the wintering period. Therefore, during the winter, the tilapia should be fed with nutrient-rich concentrates to increase its ability to resist wintering. In the early period of entering the pool, the water temperature is higher, and more materials should be put in and put in a good amount, which is conducive to the recovery and fattening of the fish. Generally, the amount of broodstock is controlled at 2%, the fish species are controlled at about 5% to 6%, and they are fed 1 to 2 times a day. It is better to feed all the fish to eat. In the middle period, the temperature is lower, and the feed should be reduced appropriately. To prevent deterioration of water quality, the amount of feeding generally accounts for 0.5% to 1% of the fish's body weight. Over the winter, the weather turns warmer and the temperature gradually rises. Management is particularly important. The amount of feed is restored to the level of the early winter, and the feed must be strengthened before leaving the pond. The quantity and quality promote healthy recovery and gonad development in broodstock, which can ensure the quality of seedlings after going out of the pond.
Feeds for fingerlings can be powdered or small-caliber compound feeds. Feeding should be done evenly throughout the pond so that most fry can eat. The broodstock feed should be dominated by buoyant particles, and the desiccant material should be set properly, and food should be finished within 1 hour. When you are finished eating, you must remove the residual materials in time and reduce the amount of feed to prevent deterioration of feed quality. Tilapia has a long wintering period. If the bait is singulated for a long time, it will often result in a lack of vitamins in the fish, which will affect the body and development. Therefore, the feeds to be fed should be diversified, mainly including foods, rice bran, bran, etc. that contain nutrients and are not likely to deteriorate, and should be fed with chopped fresh green leaves. During the winter, the type, quantity, and quality of the feed should be regulated at any time with the water temperature, water quality, and fish feeding conditions.
4. Prevention of fish diseases Due to the small area of ​​wintering ponds, high density and relatively poor water quality, the water temperature is low, and the fish is in a condition of less activity and less feeding, immunity is reduced, and it is more susceptible to bacteria, fungi and parasites. The water temperature range of the wintering pond is more suitable for the growth and reproduction of various germs, so tilapia is easy to get sick. Raising the salinity of wintering pond water to 10% can effectively control the occurrence of fish disease. Fish disease mainly adopts the principle of combining prevention and treatment. In the wintering period, quicklime is used once every half month, and the usage amount is 10~15 kg/mu. After using the quicklime for 7 to 10 days, disinfect the whole pool with 0.25 to 0.3 ppm of chlorine dioxide, and use insecticide once a month. Note that all drugs should be used alternately. Sacrifice is most common during the wintering period and occurs most often after entering the pond and before leaving the pond. Due to the low surface water temperature in the low temperature season, the fish exposed to water after oxygen deficiency floating head, easily frostbite, prone to water mold, resulting in ulceration and death, such as the discovery of oxygen deficiency in the pond, fish floating head, can be replaced with new water or oxygen. For the treatment of water mould, a 1 mg/L copper sulfate solution can be used to splash the whole cell. In addition, we must constantly check the fish's activities and find that there are abnormalities.
5. Strict responsibility system During the entire wintering period, special personnel should be assigned to manage and special personnel should be responsible for paying close attention to changes in water temperature and water quality during the winter, fish activity, and various records. Pay attention to changes in the water temperature, and often check the water temperature and temperature inside and outside the greenhouse. Usually measure 3 to 4 times a day and make a record. Adhere to the early, middle and evening patrol ponds to check whether the overwintering sheds are firm, observe the fish’s vigor and feeding conditions, regularly monitor water quality including dissolved oxygen, ammonia and other indicators in water, find problems in a timely manner, and take measures to prevent accidents. Also check the operation of various ancillary facilities such as heating and aeration and other mechanical and electrical equipment. In the late winter, due to the increase in water temperature, it is necessary to pay attention to ventilation and ventilation in wintering sheds, and the temperature of the water is stable. Then, the shed can be cooled and fresh water can be added. When the temperature of the overwintering shed is level with the outside world, preparations can be made before the pond.
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Transglutaminase For Plant Based Meat
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