First, the cause of death of fish during wintering
1. Poor environment in overwintering fish ponds, causing severe death due to lack of oxygen
The first is the aging of the pond, which has not been dredged for many years, and has a thick deposit of silt. The pigs, ducks, and ducks in the Tongtou pig and duck farm are covered with ponds. Fish (species) are cultured at high density, with high feeding, high excretion, increased organic matter, and high oxygen consumption. Secondly, there are village edge ponds and Yuzhengtang villages. The villagers live in dense areas. The domestic sewage and waste water from the nearby factories are discharged from the ponds. A large amount of oxygen is consumed and the dissolved oxygen is insufficient. In addition, carbon monoxide, carbon dioxide, and hydrogen sulfide in the water exceed the standard, which can also cause Fish (species) poisoning death; Fourth, large leakage of fish ponds, poor water retention, lack of fresh water supply, pond water shallow hypoxia, narrow space for fish activities; Fifth, new ponds, thin ponds are not fat, lack of Abundant phytoplankton, photosynthesis is weak, the amount of oxygen production can not be worthy of oxygen consumption, the fish died of hypoxia floating head infection.
2. Fish species are too small and cause death
The uneven size of the fish species, coupled with improper feeding and strong meats, result in too small a fish size, poorer constitution, and less nutrients accumulated in the body, making it difficult to maintain life activities during the long winter. The energy died because of physical weakness.
3. Injured fish died of illness
The poor operation of pulling the online market or spelling ponds caused scales, rays, and scrapings of fish scales to scratch and descale them, causing the bacteria to invade infectious diseases, and they are also prone to death during wintering.
4. Death caused by poor management
During the winter, fish farmers believe that fish do not eat or eat less feed, and relax management, do not check the water quality in time (When the oxygen content of the water drops to 3 mg/L, the fish feel uneasy; dissolved oxygen is 1 mg / L, fish breathing difficulties, a large number of floating head death; dissolved oxygen is best controlled at 5 mg / l as a safety factor), water body fat thin aging and fish activity, or have found that the fish body is not a good indicator of timely Take measures to delay the death of the fish caused by the delay. The wintering ponds leak water, and the shallow ice and snow in the ponds cause the lack of oxygen in the pool water, which will also cause the fish to suffocate.
Second, preventive remedies
1. To establish the idea of ​​"preventing the enemy and treating both the symptoms and the symptoms."
The pathogenesis of aquaculture animals must meet three conditions: First, poor aquaculture environment (including climate anomalies); Second, aquatic animals have weak physique and disease resistance; Third, pathogenic pathogens exist, and three are indispensable. According to these three principles, if we can do a good job in these three aspects, we can make the cultured species safe for the winter. Therefore, we must adhere to the principle of prevention, prevention and control, and implement a healthy and ecological aquaculture management model to achieve reduction or control of overwintering fish diseases, reduce the economic losses caused thereby, and lay a solid foundation for increasing production and income in the coming year.
2. Renovate wintering culture environment
Choose winter ponds, clear ponds and fertilize water. The quality of wintering ponds is directly related to the survival rate of fish species and the growth of adult fish.
The conditions for pond selection are as follows: leeward sunny, good water retention, adequate water supply, convenient irrigation and drainage, 3 acres to 5 acres of fish ponds, 5 acres to 10 acres of fish ponds, and water depths of 2 to 3 meters (after pond freezing in the north The water level should also be kept at about 2 meters). The conditional selection of ponds with hot spring water is most beneficial to protect the tropical and subtropical fish safely for the winter. Excessive sludge should be removed as an organic fertilizer for crops and fruit trees, repair leakage, clear the bottom of the pond, and retain 20 centimeters of sludge, and expose to sunlight, loosen the bottom mud, and fully oxidize. Then irrigated into the pond 80 cm to 100 cm, put 150 kg of lime and 50 kg of tea bran (even after 24 hours of immersion in water even slag with water spilled off the pond), quick lime and acidity, increase the pH, improve the quality of water quality, release Nutrients kill wild fish, parasites, and pathogens. In addition to killing wild fish, tea bran also plays a role in fertilizing water quality (cultivating abundant phytoplankton, which is beneficial to photosynthesis and oxygen production). After medicine, tea bran is a nutrient food that fish like to eat. After one week, the water level in Wintering Pond will be increased to 1.5 to 2 meters, and 500 kg of fermented organic fertilizer (or 5 kg of urea and 3 kg of phosphate fertilizer) will be used to fertilize the water. Adult fish can eat a lot of food after falling.
3. Improve winter and cold-resistant immunity of fish (species) organisms
Large-sized fish species are robust, full-fledged, cold-tolerant, hypoxia resistant, and anti-infective. According to the author's many years of practice, under the same conditions, the survival rate of fish species with a tail length of 12 cm or more can reach 90% after winter, and the survival rate of fish species with a tail length of 5 cm to 6 cm is 50% to 60%. It can be seen that, in the autumn of each year, fish eat heavily and accumulate fat energy for overwinter consumption. Therefore, it is necessary to feed more high-protein and high-fat feeds (such as waste from agricultural and sideline products, peanut bran, bean cake, oatmeal, and jade.ç³ ç³ é€‚ 适 适 ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ç³ ã€‚ 。 。 。 。 。 。.
Timely delivery is to master the delivery time, put in too early, high water temperature, frequent fish activities, oxygen consumption, physical fitness, net abrasions are also easy to infect red skin and other diseases; too late, the weather is cold, Pulling nets and scraping fish also damages the surface of the fish and is susceptible to hydromycosis, and it also causes massive deaths. Therefore, it is generally recommended that ponds be fished when the water temperature is between 12°C and 15°C in mid-November (fish activity is reduced, scales are compact, and the nets are not easily scratched).
Fish (seedlings) stocking, single species breeding, multi-species polyculture, so it should be divided into varieties, sub-standards, eating habits. For example, the cultivation of filter-feeding eel can account for 70% of the farmed fish, with 20% of grass carp, 10% of ground omnivorous fish (single species of tilapia or earth carp, etc.), and vice versa. same. If you are breeding bottom fish (tilapia, earthfish, earthworms, oysters, etc.), do not polyculture, because these fish have similar food habits and habitable water levels, which can easily lead to catching food. Big fish bully small fish and cause small fish. The first death. It is suggested that the single species cultured in single ponds should be based on the same size fish species. For example, 70% of earth carp (species), 20% of carp, and 10% of grass carp can fully utilize the fish food chain for mutual benefit and healthy breeding.
The stocking is too dense, there is insufficient feed to eat, the fish grows in different sizes, the activity space is small, the water level drops, and it is prone to lack of oxygen. If it is too sparse, it is a waste of water space. In general, 30,000 to 40,000 fish species are distributed in more than 10 centimeters, and 10,000 or less are used in water-resource supplementation. If it is a fish pond breeding, general acre put 300 kg can not be listed on the adult fish, but also how much to catch back, what to catch what to put, keep the fish is relatively stable, it is beneficial to increase production and income. It is also necessary to adjust in time according to the specific conditions such as breeding techniques, feeds, water sources, varieties, specifications, and density, and cannot copy photos. At 2 am to 3 pm noon, no wind, light and water temperature are normal when stocking. Quarantine before stocking, immersing the fish body with 4% to 5% salt water, and sterilizing after ten minutes.
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