Tilapia is a tropical fish. It is not tolerant to low temperatures. The water temperature for living and growing ranges from 15°C to 38°C, and the optimum temperature is 28°C to 32°C. When the water temperature drops below 12°C, feeding is stopped, and the temperature below 9°C will gradually decrease. death. Under normal conditions, tilapia must be taken overwintering measures when the water temperature drops to 15°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 spring waters, deep water wells, and boiler 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.
Preparation before winter
The overwintering fish requires that the wintering fish be raised in a special pool for the month before the winter to carry out strengthening and cultivation, so as to promote the cultivation of their fat and strengthen their overwintering and cold resistance so that they can gradually adapt to the living environment during the winter and will be partially frail or Injured fish were eliminated in advance.
The selection of overwintering fish should be selected from the fish species cultivated in the special pool for autumn seedlings. The overwintering species should be 5 cm to 6 cm in length. The overwintering pond utilization rate will be reduced as a result of the general meeting. Oversized winter fish species 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 of common seedlings requires that the specifications should be neat and tidy when entering the pond. Tilapia breeds many times a year. The specifications of the fish when the fish enter the pool are uneven, and it is inevitable that they will appear to be small bullies, poor development of the weak, or even death.
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.
Preparation of wintering 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. Pre-repair all wintering equipment. When a general farmer goes through a small area for winter, two 3 kilowatt electric heaters should be used for every 30 cubic meters of water. During the 7 days to 10 days before wintering, fish ponds, pipes, and channels should be treated with quicklime, bleach, or other disinfectant drugs in a manner consistent with the treatment of pond cultured fish.
When the fish body is disinfected before winter, the broodstock and fish species have different degrees of damage during transportation and operation. The fish body should be disinfected before entering the pool, and 2%~3% salt solution (industrial coarse salt) can be used. Soak the fish for 5 minutes 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.
The time of wintering fish entering the pool and its precautions
Into the pool time into the pool overwintering time, should be mastered in the water temperature down to 20 °C ~ 22 °C into the overwintering pool is appropriate. The specific pooling time varies with the climate in different places. However, it must enter the overwintering pool when the water temperature is above 20°C. It must be completed before the first cold current. If the water temperature is lower than 16°C, then the catching fish cannot be used for wintering, because the fish body has frostbite and enters the pool. It will produce water mold and will continue to die. Fishing overwintering fish should choose wind and sunny weather, so as to avoid fish frostbite.
The density of stocking densities of wintering fish into the pool depends on the environment conditions of the wintering pond, fish size and management level. The temperature of the flow pool is lean and there is sufficient dissolved oxygen. Generally, 12 to 20 kilograms of broodstock can be placed per cubic meter of water, or 8 to 12.5 kilograms of fish can be released. The hydrophile pool can hold 5 kilograms of broodstock per cubic meter of water. Kilograms, or 3.5 kg to 5 kg of fish species; static pools, which can change water regularly, can contain 2.5 kg to 4 kg of broodstock or 2 kg to 3 kg of fish per cubic meter of water.
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.
Water Temperature Control Overwintering fish can control the water temperature at 20°C~25°C within 10 days after entering the pool, which is beneficial to the healing of light wounds, inhibiting the occurrence of water mildew, and increasing the survival rate of overwintering. After the situation is basically stable, the water temperature is required to be maintained above 16°C throughout the winter, and the general water temperature is 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 or more, long-term high temperature is not conducive to winter management, but also increase feed consumption, because the water temperature is high, 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.
The overwintering pool for water quality regulation should keep the water quality fresh. During the wintering period, water quality analysis should be performed frequently. Attention should be paid to observing the flotation conditions of fish schools 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 the wintering fish into the pool, due to a lot of waste, should be a day of suction, after the week should be dirty or flushing 1 or 2 times. At the same time, change the water once in the early days, and change the water every 3 days to 5 days. 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 sprinkling 0.5 kg of 30% hydrogen peroxide in water of 10 cubic meters to relieve the serious floating head.
Feeding tilapia on feeds consumes a lot of energy during the wintering period. Therefore, during the winter, tilapia should be fed with nutrient-rich concentrates to increase its ability to resist overwintering. 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. General feeding amount of broodstock is controlled at about 2%, fish species are controlled at about 5% to 6%, and they are fed once or twice 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. In order to prevent the deterioration of water quality, the amount of bait generally accounts for 0.5%~1% of the fish's body weight. The warming of late winter and the gradual increase of temperature make the management more important. The amount of feed is restored to the level of early winter and must be strengthened before leaving the pond. The quantity and quality of feeds will promote the recovery of healthy body and development of gonads and ensure the quality of seedlings after discharge.
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 mainly buoyant pellets, and the desiccant material should be set properly, and it is advisable to finish eating within one 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.
The prevention of fish diseases is due to the small area, high density and relatively poor water quality of overwintering pools. When the water temperature is low and the fish is not active and eating less, the immunity is reduced, and it is more vulnerable to bacterial, fungal and parasitic infestation. The water temperature range of the wintering pond is also more suitable for the growth and reproduction of various bacteria, 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 amount used is 10kg/mu~15kg/mu. After using the quicklime for 7 days to 10 days, 0.25 ppm to 0.3 ppm of chlorine dioxide is used for the whole-tank disinfection, and an insecticide is used 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 mold, a 1 mg/L copper sulfate solution can be used for Quanchiposa. In addition, we must constantly check the fish's activities and find that there are abnormalities.
5. Strict responsibility system
Throughout the winter period, special personnel should be assigned to manage and special personnel are responsible for paying close attention to the changes in water temperature and water quality during the winter and the fish’s activities, and to make good records. Pay attention to changes in water temperature, and often check the temperature and temperature of the water inside and outside the greenhouse. Usually measure 3 times 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.
Sk5 Blade,Sk5 Material Spare Blade,Utility Knife Spare Blade,Utility Knife Ultra Sharp Blade
Shangqiu City Huashang Zhiyuan Tools Co., Ltd. , https://www.hszytools.com