With the development of the aquaculture industry in recent years, the scale of aquaculture has become larger and higher, and the level of technology has become higher and higher. Therefore, farmers' expectation for the benefits of aquaculture has gradually increased. Therefore, the management of the aquaculture process has gradually become more important. Many fishermen found that the effect of feeding on fish was not the same during feeding. Based on the experience of doing technical services in recent years, the author would like to elaborate on his own views for reference. I. Hypoxia Dissolved oxygen is a necessary condition for determining whether fish can live in water. The reduction or increase of dissolved oxygen in water directly affects the food intake and growth of fish. Under normal circumstances, there are three main sources of dissolved oxygen in the water of aquaculture ponds: (1) O2 dissolution in the air; (2) Photosynthesis oxygenation of phytoplankton; (3) Oxygen supplementation of exogenous waters, but the most important Or photosynthesis oxygenation. There are two main reasons why fish feel that water is deprived of oxygen: 1. The low dissolved oxygen content of the water is mainly caused by the following factors: (1) Oxygen consumption of zooplankton in water such as rotifers, cladocera and copepods, etc. Excessive amounts of zooplankton, on the one hand, themselves consume the dissolved oxygen in the water while eating most of the algae in the water. If the body of water does not supply dissolved oxygen for a short period of time, the fish will float or even die. When this kind of situation arises, it is necessary to kill too much zooplankton and then use it for water training. If it is a small zooplankton such as rotifers, it is recommended that copper sulfate be used for killing, if it is a large zooplankton such as Cladocera and Copepods, fishermen can choose to use the width of about a meter along the edge of the pool in the early morning or early evening with 90% crystal trichlorfon water spill, can effectively reduce the amount of zooplankton in the water. (2) Unbalanced Algal Phases The more common algae in culture ponds are mainly Chlorella, Euglenophyta, and Cryptophyta. Occasionally, some species of Pyrrophyta, Chrysophyta, and Cyanophyta can form dominant populations under certain conditions. According to the author's experience, the algae in aquaculture ponds is generally dominated by green algae and naked-dendron algae, with a small amount of cryptophytes and eutrophic algae. This type of water-body fish eats better. In a pond with too many algae, fish will generally eat poorly, especially during the middle and late stages of farming. The ponds are too fertile and cause massive occurrence of algae. This type of fish usually eats poorly and the water environment is unstable. In the event of rainy weather, the massive death of eutrophic algae can easily lead to flooding. In addition, due to the large size of the population, the photosynthesis oxygenation can be carried out during the day, but oxygen consumption is very high at night. Therefore, a large number of ponds that produce eutrophic algae should regularly change the water and then use copper sulphate or strong chlorine fines to splash the whole pool, which can effectively reduce the amount of eutrophic algae. Three or four days after the pouring of the drug, Bacillus spp. Excessive single algae, mainly due to the fact that the nutrient elements in the pond are too single, are beneficial to the growth of certain algae, while the growth of other algae is limited. Therefore, it is recommended that fishermen should use organic fertilizer as the base fertilizer in the early stage of fertilization. In the middle and late stages of cultivation, the main fertilizers are mainly inorganic fertilizers and supplemented by organic fertilizers. At the same time pay attention to regularly add new water, splash lime to adjust the pH of the water body. (3) The type and amount of phytoplankton in the water is too low. The dissolved oxygen in the water is mainly provided by the photosynthesis of the plants. When the amount of phytoplankton is small, the water needs fertilization to cultivate algae. Generally, the organic fertilizer can be selected after fermentation. Pigs, cow dung and inorganic fertilizers such as nitrogen fertilizer 4-6 kg/mu, phosphate fertilizer (superphosphate 2-3 kg/mu) are used in combination. In addition, the turbidity of the water can also cause poor photosynthetic effects. This type of water is generally first purified with alum or aluminum chloride and then fertilized to avoid affecting fertilizer efficiency. (4) The mode of stocking is unreasonable. There is a certain limit to the amount of fish in the aquaculture water. Too many seeds will cause long-term discomfort in the fish itself, and it will also cause oxygen deficiency due to excessive density. In addition, the collocation of certain cultured species is also critical, such as the main grass carp paired with white peony, which is conducive to keeping the water fresh and promoting the growth of grass carp. Many fishermen are not willing to breed whitefish in ponds due to their low price and easy to lack of oxygen, resulting in large numbers of algae breeding in the middle and later stages of cultured ponds, especially for cyanobacteria. Therefore, a reasonable breeding model and a reasonable mix of cultured species are the necessary conditions for ensuring high aquaculture production. 2. The body's intake of dissolved oxygen is low. Most fishes mainly rely on earthworms to complete the exchange of oxygen. The fish body cells need to get dissolved oxygen from the water body. They must go through "dissolved oxygen from the water - transport in the body - - Three steps to supply oxygen to the organization. Absorption of dissolved oxygen from water is done mainly by helium, if the thorium tissue is damaged or there is dirt, short fibers, oils, corrosive poisons (such as strong alkalis, heavy metal salts, certain organic acids, hydrogen sulfide, etc.) Under abnormal conditions, there is a large amount of mucus on the silk (for example, parasitic parasites or bacterial rotting), and foreign matter is stuck on the silk, which reduces the surface area of ​​the silk and forms a barrier between water and blood. These will reduce the speed and efficiency of the oxygen absorption from the water by the thorium tissue. When oxygen enters the bloodstream, it must be combined with hemoglobin, but if the nitrite content in the water is too high, this chemical change will be affected, which will prevent the exchange of dissolved oxygen in the fish and cause physiological anoxia. Even if the dissolved oxygen content in the water is high, the fish cannot absorb the oxygen in the water. Fish anorexia caused by high nitrite will generally last long. If this happens, fishermen must first reduce the concentration of nitrite. Wherever possible, large amounts of water can be changed and then degraded by biological agents such as photosynthetic bacteria and nitrifying bacteria. Second, the disease here mainly refers to parasitic diseases, enteritis disease, bacterial erosion and hepatobiliary disease. Among them, parasitic diseases mainly include ectoparasite trichomonads, ringworms, anchorheads, Chinese sturgeons, and intestinal parasites. The number of these parasites affects the feeding of fish. For example, the head mistletoe on the body surface not only affects the fish restlessness or anorexia, but also affects the growth of the fish body. The number of worms parasitizing in the intestinal tract will block the intestinal tract for a long time, making the fish unable to ingest food. Intestinal inflammation can cause destruction of the intestinal wall membrane of fish, so that the fish can not normally secrete the corresponding enzymes, affecting the digestion of fish. Bacterial gills mainly destroy the silk tissue and reduce the surface area of ​​the gill filaments. In this case, it is first necessary to identify what kind of pathogen is caused by the gills. If the parasite first kills insects and then disinfects them, the trilobites of the protozoa are selected to be killed by copper sulfate. The worms of the ringworm and the three worms can be used. Trichlorfon or mebendazole to kill, and the crustacean of the head, Chinese sturgeon can use deltamethrin, trichlorfon and other kill, intestinal aphid use albendazole spices, continuous oral administration of 3-5 days . The anorexia caused by hepatobiliary disease is mainly due to the increase of the density of culture in recent years, the deterioration of the water environment, artificial enhanced feeding, indiscriminate use of drugs, vitamin deficiency, rancidity of feed, imbalance of nutrients, and toxic substances in feed. Etc., damage to fish liver. The prevention of liver diseases should be strictly in accordance with the requirements of scientific fish culture, to cultivate good water quality, formulate feeds that are rich in nutrients and comprehensive, and of good quality, scientifically fed, and avoid overfeeding; prevent protein deterioration and fat oxidation, and prevent feed from getting mold and deterioration. The principle of treatment is the regeneration of cells and the restoration of gallbladder function. To prevent and treat liver diseases, Chinese herbal medicine prescriptions with detoxification and liver protection, liver respiration and liver rejuvenation, and promotion of liver cell regeneration are used to treat liver diseases such as Angelica sinensis, Radix Paeoniae Alba, Salvia miltiorrhiza, Yujin, Bupleurum, Radix Astragali, Codonopsis, Chinese yam, habitat, Alisma, Banlangen, and Hawthorn. Licorice and so on. The general seasoning treatment period is 5-7 days for one course of treatment. Severe illness can be followed by a course of treatment after two and a half months. Third, poisoning poisoning directly affects the feeding of fish, and severe poisoning can also endanger the life of fish. Poisoning mainly includes algal poisoning, pesticide poisoning, heavy metal poisoning, chemical poisoning, food poisoning and drug poisoning. 1. Algae Poisoning The main cause of fish poisoning in freshwater bodies is the microcystis of Cyanophyta and the triatoma of Chrysophyta. Microcystis has a large number of reproduction. After death, protein breakdown produces toxic substances such as hydroxylamine, hydrogen sulfide, etc. Light affects fish feeding and severely poisons fish. The pond with too much Microcystis can splash 0.7mg/L copper sulfate or copper sulphate and ferrous sulfate mixture (5:2) in Quanchipia. Immediately after spraying, start the oxygen machine and add a certain amount of fresh water in the morning. Prevent fish from floating. The poisoning caused by Trichophyton alkaloids is mainly caused by the massive reproduction of trichophyton, producing a large amount of fish toxins, cytotoxins, hemolytic toxins and neurotoxins, causing fish poisoning. In the case of fish poisoning caused by Tricholimus sp., fresh water is first added, and then 4 kg of ammonium hydrogen carbonate is used in a one-meter-mu water depth to allow the triatomas to swell and disintegrate until they die. In addition, the growth of other algae is cultivated by fertilization to inhibit the mass reproduction of Algae. 2. Pesticide poisoning (1) Organochlorine pesticides such as DDT, BHC, etc.; (2) Organophosphorus insecticides such as trichlorfon, dichlorvos, etc. These types of poisons are obvious to fish skin in a certain range of categories. The toxic and poisoning pathways are mainly through the respiration of fish, skin contact, swallowing contaminated feed, etc.; (3) Organic sulfur pesticides such as zeocin and dexanammonium. The emergence of pesticide poisoning, first of all should be a lot of water to dilute the concentration of toxic substances, it is best to find out the pollutants, symptomatic use of antidote drugs. 3, heavy metal poisoning The toxicity of heavy metals to aquatic animals is generally the largest mercury, silver, copper, cadmium, lead followed. The main damage mechanism is that the heavy metal ions combine with the mucus secreted by the fish gills to become a complex of proteins covering the entire septum and filling the gaps of the gill filaments, obstructing the contact surface between the gill tissue and water, and making it unable to exchange gas. Suffocated and died. In addition, once the heavy metal enters the fish body, it accumulates in the body and binds with the sulfhydryl group in the catalytic active site of the main enzyme of the fish body to form an insoluble sulfate, thereby inhibiting the enzyme activity and impeding the metabolism of the body. The pollution of heavy metals is mainly due to the discharge of wastewater from chemical plants to aquaculture ponds. Therefore, the cultured ponds should be far away from industrial areas. 4. The poisoning of chemical substances mainly includes ammonia nitrogen, nitrous acid, salt hydrogen sulfide, petroleum pollution, and phenol poisoning. Ammonia nitrogen and nitrous acid in the aquaculture pond can also cause fish anorexia and even poisoning. Many fishermen know that the pH of water bodies is significantly higher than in the morning on sunny afternoons. When the pH and ammonia nitrogen are high at the same time, it will cause ammonia poisoning. Therefore, the reason why fish eat well at noon and afternoon can be imagined. The ammonia-nitrogen ponds can be exchanged in large amounts under conditions, and then 20-30 kg of zeolite powder can be splashed in the whole pool, which can effectively reduce the concentration of ammonia nitrogen. 5. Food Poisoning Most fish cultures rely on the feeding of compound feeds. If fish eats spoilage feed, it can also cause poisoning, anorexia or death. 6, excessive use of drugs poisoning insecticides such as copper sulfate, trichlorfon, and high doses of feed in the feed for a long time to cause fish liver poisoning, can cause fish anorexia. Therefore, the correct medication is the key. Fourth, bait 1, feed too hard or too long water-soluble feed hardness can directly affect the intestinal digestion and absorption of fish and palatability, induced indigestion and enteritis, will cause anorexia for a long time; early spring feed hardness is too easy to cause early spring The feed acclimation effect is poor. The feed sinks too fast and the fish do not float easily, resulting in poor enthusiasm for eating. 2, feed deterioration has been described previously. 3. Poor feedability of the feed itself Poor raw material for feed and some raw materials with heavy odors are too low to reduce the feed intake of the feed. The feeding rate of the fish is definitely not good, and it will inevitably cause anorexia. 4. If the feed grain size is too large or too small, it will affect the feeding of fish. The feed grain size should be selected according to the different specifications of the fish body. 5. Sudden refueling during the restocking process may cause the farmed animals to be unadapted to the taste for a short period of time, and may also cause the fish to eat less or anorexia. Therefore, when the farmer reloads materials in the middle, the two feeds must be firstly proportioned. Mix together for a period of time and slowly adjust the ratio until it is completely replaced with a new breed of feed. V. Climate 1. Water temperature is too low Fish are a temperature-changing animal, and feeding must reach a certain temperature. If the water temperature is very low in the early spring, the fish will not be very busy. Therefore, the water depth of the pond should not be too deep in early spring, and the water level of the seed pond is maintained at 0.8-1.5 meters, which is conducive to the increase of water temperature, so that the seed can be fed as soon as possible. 2, sudden changes in the weather such as temperature sudden changes caused by sudden changes in water temperature, continuous rainy weather, hot weather and typhoon landed and other changes in the water quality of aquaculture, so that fish stress, will appear anorexia for a short time. In addition, in addition to the above causes of fish anorexia, artificial spillage of drugs, a large number of water changes, after fishing, in the feed when mixed with drugs when feeding and belong to the breeding season will cause fish anorexia. Therefore, farmers need to find out the cause according to the specific situation and solve it symptomatically.
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