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First, managing the source of water well is the fundamental basis for the survival of fish. It determines the conditions of water quality and the success or failure of breeding. The selection of water sources will determine the basic conditions of water quality. To do water quality control, we must first understand the water quality parameters of the water, including pH, dissolved oxygen, ammonia nitrogen toxicity, total nitrogen, nitrous nitrogen and salinity. The optimum pH of freshwater aquaculture water is 7.5-8.5. When the pH value drops below 7, the quicklime should be used to raise the pH value. If the pH is found to exceed 9 or more, the fresh water should be adjusted in time. Dissolved oxygen must be controlled at more than 5mg/L. Water is rich in dissolved oxygen. Microorganisms can convert some toxic metabolites such as ammonia nitrogen, hydrogen sulfide and methane into non-toxic or slightly toxic nitrate ions, sulfate ions and carbon dioxide. Mild hypoxia does not kill fish and shrimp, but it can cause symptoms such as irritability and rapid breathing, leading to slower growth; severe hypoxia can cause death. Ammonia nitrogen in water mainly comes from the feed, fertilizer and excrement of aquatic animals. This requires that the water body should be cleaned and the feeding of feed and fertilizer should be well done in the early stage of cultivation. The appropriate amount of zeolite powder can be used to improve the bottom sediment in the middle and late period of culture. Ammonia, degrade organic matter. Nitrite in water should be controlled below 0.1 mg/L, CO: not more than 20-25 mg/L, hydrogen sulfide not exceeding 0.2 mg/L, and phytoplankton amount between 20 and 100 mg/L. Water sources also require stable, adequate, clean, sanitary water, suitable water temperature, good water quality, and no pollution. They are in line with the national fishery water quality standards, and require that the injection and drainage are convenient, and single-injection single row should be built at the injection and drainage outlets. Barrier nets can prevent fish and fish from entering the pool and prevent the escape of fish. Before the water enters the culture pond, it must be filtered and disinfected in the reservoir to kill pathogens and predators. Generally, 25 to 309 quicklime or 19 bleach (containing more than 25% of available chlorine) per cubic meter of water can be splashed. When pests need to be killed, 0.59 trichlorfon (90% of the crystal trichlorfon) can also be used to splash the whole pool.
Second, biological regulation and utilization of biological methods, can adjust the structure and function of fish pond culture system, so as to achieve the purpose of improving water quality. On the one hand, it can properly transplant aquatic plants to regulate water quality. Aquatic plants as the primary production of water can control the growth of fish ponds and other algae, and play a very good role in water purification. According to the actual situation of the fish ponds, the farmers can adjust the water quality according to local conditions and scientifically plan the introduction of aquatic plants such as black algae, Houttuynia cordata, water hyacinth, and duckweed in the water body. However, care must not be taken blindly to avoid secondary pollution. On the other hand, aquatic animals can be properly transplanted to regulate water quality. Aquatic animals are the "consumers" in the water body. Proper transplantation can promote the balance of water ecosystem and achieve the role of regulating water quality. Such as nesting squid and squid can make full use of the residual organic matter in the water, greatly reduce the decomposition of organic matter at the bottom of the water, reduce the probability of occurrence of pollution; sleek herring can inhibit the consumption of nutrients and oxygen in water by organisms such as snails and other organisms. Sets of squid can make full use of the natural bait resources such as plankton in the water to control the water body fatness so as to achieve the effect of regulating the water quality. The squid can inhibit the rotifers in the water body; sets of raising grass, squid and squid It can ensure adequate dissolved oxygen in the water body and purify the breeding environment. Raising the stingray can inhibit the anchor head in the water body and reduce the water body pollution; the nesting of squid, black peony and squid can effectively control the growth and reproduction of wild fish and shrimp in the water body. Reduce competition pressure with the main fish for food and competition. At the same time, microecological agents can be used to scientifically regulate water quality. Microecological preparations use Pseudomonas aeruginosa, Bacillus subtilis, and nitrifying bacteria to treat water pollution, degrade the concentration of harmful substances produced by fish excrement, residual food, fish and shrimp corpses, and chemical drugs, and promote a healthy cycle of water quality.
Third, a reasonable amount of fertilization fertilizer affects both the growth of fish and shrimp, but also affect the changes in water quality. When breeding, it is also possible to moderately fertilize the plankton in a good state of growth, increase the dissolved oxygen and nutrients in the water, and cultivate good water quality to assist the growth of fish and shrimp. Generally from May to June, organic fertilizer is mainly used, once every 7 to 10 days; from July to September, it is mainly applied chemical fertilizer and once every 4 to 6 days. For ponds mainly for cultured alfalfa and cockroaches, the fertilization should be based on the water quality of the pool and the weather conditions. Generally, the water transparency should be about 25era, and the water should be dark brown. At the same time, it should be noted that the amount of fertilizer should not be too much, pay attention to less applied facilities. Human and animal manure and other organic fertilizers can be applied at a rate of 100 to 150 kg per acre per mu; each mus of fertilizer uses 1.7 kg of urea or ammonium sulfate and 1 to 1.5 kg of superphosphate.
Fourth, regular water injection High quality intensive pond water quality requirements "fat, live, tender, cool." For ponds with sufficient water sources, whether to add water or change water can be determined based on the degree of transparency. The transparency of the pool water in general intensive fish ponds should be maintained between 30-40 cm. The pool water is too dark and the transparency is less than 20cm. It can drain some of the old water and add some new water. In the case of high-density farming, there are more baits and dirt in fish ponds, and anaerobic fermentation produces harmful substances such as ammonia nitrogen and hydrogen sulfide, which results in deterioration of water bodies. Especially in the summer hot season, the water quality changes more quickly. Regular water injection is the regulation of water quality. The most commonly used and one of the most economical methods. When the deterioration of the pool water is severe, water changes should be adopted to maintain good water quality conditions. For ponds mainly for raising pupa and squid, the water color should be kept green or dark brown with a transparency of 20 to 30cm. For ponds mainly for raising grasses and squids, the water color of the ponds and squid ponds should be slightly lighter, every 7 to 10 About a day should be filled with fresh water, each time should increase the water level 15-20cm, in summer ponds should try to maintain the highest water level. Each time the amount of water to be replaced should be about 1/3 of the original pond water, it cannot be filled with large rows, so that the physicochemical factors of the pool water will be drastically changed. When the water is changed, the water temperature difference between the pool water and the water source cannot exceed plus or minus 2°C, otherwise the pool fish will be generated. Stress reaction, causing disease.
V. Timely oxygen enriched fish ponds In the middle and late stages of aquaculture, due to the high organic matter content of the pool water, the oxygen consumption of organic matter at the bottom of the pool increases, and hypoxia is a very common phenomenon. The timely opening of aeration equipment not only increases the amount of dissolved oxygen in the water, breaks down water stratification, compensates for oxygen debts, reduces the diurnal variations of dissolved oxygen in fish ponds, and the differences in the distribution of water layers during sunny mornings, but also increases and balances the dissolution of the entire body of water. Oxygen content stabilizes the acidity and alkalinity of pool water. It also effectively removes harmful gases such as ammonia, nitrogen, and methane from the water, and promotes organic matter in the pool water to be decomposed into inorganic matter by the action of aerobic bacteria, and is absorbed and used by phytoplankton and inhibited. The breeding of anaerobic bacteria reduces the damage of anaerobic bacteria. Generally about 5 acres of fish ponds must be equipped with a 3.0kW aerator, generally sunny noon, cloudy early morning the next morning boot, rainy season in the middle of the night boot, and in the evening and rainy days do not boot during the day.
6. Stirring sediment In the hot season, the organic matter at the bottom of the pond undergoes oxidative decomposition under the action of bacteria, consumes large amounts of oxygen, causes oxygen deficiency in the bottom of the pool water, promotes the growth of anaerobic bacteria, and makes ammonia nitrogen, nitrite, and hydrogen sulfide in the pool water. Increased levels of harmful substances such as methane. Turning the sediment regularly can promote the decomposition of organic matter at the bottom of the tank, release harmful gases, and reduce the content of ammonia nitrogen, nitrite and hydrogen sulfide produced by anaerobic respiration of bacteria. Generally every one week or so, turn the sediment at noon on sunny days, and flip the bottom 1/3 of the pool each time. It should be noted that after turning the sediment, old ponds will cause outbreaks of protozoa and rotifers, leading to sudden changes in water quality, resulting in dead fish that can be killed by splashing 1 g of crystal trichlorfon per cubic metre of water.
VII. Drug regulation Regular use of quicklime and other drugs in fish ponds can play an important role in purifying water quality, regulating the pH of water bodies, improving the breeding environment and preventing fish diseases. When quicklime is used to regulate water quality, it is usually splashed once per half a gram of lime with 15 to 20kg of water per acre. Due to the excessive concentration of water in the pool water, the cyanobacteria bloom too vigorously to form water blooms, resulting in a high pH in the pool water. It is possible to use 0.79 cupric sulfate per pool to control the over-breeding of cyanobacteria. In the intensive cultivation ponds, in the middle and later stages of cultivation, there will be a sudden and large number of protozoa breeding, which will cause a drastic reduction in the number of phytoplankton, a decrease in pH, and a drop in dissolved oxygen, which will turn the pool water into grayish or red water, which may result if it is not timely rescued. The whole pond fish died. At this time, O. per cubic meter of water can be used. 7 to 1.0 g of crystal trichlorfon was splashed in the whole pool to kill the protozoa in the pool. If there are too many organic suspended substances in the pool, 20-25kg of zeolite powder per cubic meter of water can be splashed across the pool to reduce the oxygen consumption of organic matter and increase the transparency of the water body. In the event of fish floating heads, oxygenation agents and other related drugs may also be used to increase oxygen.
VIII. Strengthen management Fish ponds often suffer from lack of oxygen floating head due to excessive water quality and hot weather, which can easily cause dead fish. To strengthen prevention, it is usually more than three times a day to inspect the pond. The key period is dawn, noon, and evening. Check the food condition and whether there are signs of floating heads. It is necessary to timely remove the bait and dirt from the pond and the feed table, and remove weeds from the pool. When the signs of floating heads are found, fertilization should be stopped and the amount of feed should be controlled, and oxygenation measures should be taken immediately. Found dead fish and shrimp in the pool, should be promptly removed, check the cause of death, symptomatic treatment, while the dead fish and shrimp should be kept away from the deep-buried treatment, so as not to damage water quality, induce fish disease or make the fish disease spread. In the breeding, we must also pay attention to the rotation of the catcher. With the rapid growth of fish and shrimp, the amount of fish on the pond will increase significantly, and the probability of deterioration of water quality will increase. At this time, attention should be paid to the use of wheel catcher to release water space and control. The amount of fish contained in a good body of water can be used to control water quality and prevent problems.
Intensive fish pond water quality control measures
Pool water is the environment in which fish live, and the quality of pond water is one of the important factors that determine whether the pool fish can grow healthily and obtain high yield. For high-density precision cultured fish ponds, if the water quality is poorly managed, if water is not added or changed, or water quality adjustment measures are not taken for a long time, the water quality of the pool water will be easily deteriorated, the water in the pool will be deprived of oxygen, and the content of harmful substances will increase. In ponds and outbreaks of fish diseases, the growth of pond fish is inhibited and the fish are killed. To do a good job in the regulation of pond water quality is to accelerate the growth of fish, reduce the incidence of diseases, improve the utilization of feed, and achieve the key to stable production and high yield.