Measures to improve the Survival rate of two-year-old Grass Carp fingerling by culturing Grass Carp

The main reason for the low survival rate of one-and two-year-old grass carp fingerling

1. If the pond is not cleared or the pond is not cleared thoroughly before stocking, it is easy to cause poor bottom quality of the pond, and there are a large number of pathogens at the bottom of the pond. If the climate is changeable and the water quality is unstable this year, it will cause sporadic death of fish species.

2. The fish species were released without fertilizer and water after clearing the pond. according to the investigation, many farmers released fish species after pond cleaning, resulting in rapid change and instability of water quality, resulting in new stress of two-year-old grass carp fingerling. At the same time, there are few palatable bait organisms after grass carp are planted in the pond, resulting in slow growth of dust, poor physique, easy to grow, low survival rate and intermittent death.

3. Poor water environment due to unstable pond water quality, coupled with large climate change, it is easy to lead to grass carp suffering from hemorrhagic disease, rotten shad disease and other diseases, resulting in low survival rate. Especially in the ponds fed with pellet feed, with the increase of fish load and feed feeding in the ponds, the water quality is more difficult to control, easy to aging and deteriorate, and the contents of harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide increase rapidly, causing chronic poisoning of fish species and intermittent death of two-year-old grass turtle species.

4. Unreasonable feed many farmers like to feed high-protein feed, thinking that high-protein side feed will increase the growth rate of grass carp, ignoring the nutritional needs and balance of grass carp, coupled with the lack of vitamins in the feed, especially the lack of vitamin c content, the result often leads to the occurrence of fish nutritional diseases (such as fatty liver, liver degeneration, etc.).

5. some farmers with unreasonable disease prevention measures have poor awareness of disease prevention, and rely too much on and believe in the role of drugs. in the process of breeding, they are enough to prevent diseases in accordance with the traditional methods of disease prevention, and some antibiotics are often added to the feed to prevent diseases, while ignoring the fundamental role of improving the ecological environment of water bodies and the scientific use of substances. As a result, excessive use of drugs leads to strong drug resistance of pathogens and serious damage to the internal organs (such as liver, kidney, spleen, etc.) of grass carp fingerness. so that the grass carp's own digestion, detoxification, anti-epilepsy ability is greatly reduced:

2. Measures to improve the survival rate of two-year-old grass carp fingerling culture; the growth of two-year-old grass carp species has higher requirements on the water environment, especially under the condition of intensive culture in ponds, we must pay attention to every link of the culture process and promote ecological culture and healthy culture. The rest measures are as follows:

1. Thorough pond cleaning and disinfection is the basic environment for fish survival. At the same time, thorough pond cleaning and disinfection is the basis for creating a good ecological environment for fish culture. The bottom quality is good, the water quality is naturally good, and the bottom quality is good. Therefore, pond cleaning and disinfection is very important. It is one of the "most critical" measures for ecological and healthy fish culture technology and successful culture. In order to clean up and disinfect the pond, first, it is necessary to remove too much silt, thoroughly expose the sun, improve the substrate, block leakage and prevent seepage (to prevent the "series" spread of the virus), so as to create a good "living" environment for the healthy growth of fish; the second is to use disinfectants to kill enemies in the pond. The specific operation is to clean the pond with medicine 10-15 days before stocking. The water at the bottom of the pond is 10-20 cm and 150-200 kg of quicklime is now splashed. Wash away the quicklime water after 5 days, and then you can inject new water. The water injection outlet should be equipped with a filter to filter out pests and impurities. Then the whole pool can be sprinkled with bromochlorohydantoin 20000g / mu to kill pathogens and pests quickly and thoroughly.

2. Scientific fertilization management of fish species before stocking, fermented organic fertilizer is used to fertilize and water, cultivate natural bait organisms, make the water yellowish green or tea brown bag, the water should be fat and cool, create a good algal phase, the transparency is kept at 30-40 cm, the pH value is 7. 5-8.0, so that there is enough live bait, and at the same time, the food organisms are especially sufficient for plankton to purify water quality and absorb harmful substances such as ammonia nitrogen and hydrogen sulfide in the water. Stabilizing water quality plays an important role. There are many algae, which is a sign of enhanced purification ability of water body. Only abundant algae can make full use of the products of microbial degradation, so algae are the main body of plankton in water body, and the life span of algae itself is only 10 to 15 days. The normal growth of algae (including living bacteria) requires nutrient elements such as nitrogen, iron, zinc, copper, cobalt, magnesium, potassium and a variety of retinoids. Therefore, it is necessary to sprinkle biological fertilizer and water agent regularly to supplement nutrition. At the same time, pay attention to do not change a large number of water, it will cause algae not enough nutrition supply, algae will die faster, poor reproduction of algae and living bacteria will lead to unstable water quality. Therefore, water exchange should be reduced and nutrient sources should be properly supplemented in order to maintain the stability of algae in the pond and maintain the ecological balance in the pond.

3. Necessary disease prevention measures before stocking two-year-old grass carp fingerling must be soaked with 0.2mg / 10 times diluted single fish hemorrhagic disease inactivated vaccine or special grass carp vaccine. The method is to soak the fish in a solution of 0.5% inactivated vaccine plus 1.0 mg / L scopolamine for 2 hours to prevent the occurrence of grass carp viral hemorrhagic disease in the process of breeding. Or soak the fish for 15 minutes with 5 mg / L amino acid iodine solution for 20 minutes to kill the viruses and bacteria that may be carried by the fish itself and enhance the immunity and anti-virus ability of the fish:

4. Improve the feed nutrition of two-year-old grass carp fingerling with high-quality feed and reasonable feeding to ensure that the fish are well-fed, well-fed and well-fed. Prepare reasonable special feed according to the nutritional requirements of grass carp fingerling, and add high-quality vitamins and minerals to prevent vitamin deficiency. At the same time, during the whole culture process, the feeding amount of compound feed should be adjusted reasonably according to the living habits and disease characteristics of grass carp species, and the feeding amount of all kinds of high-quality water early grass should be increased appropriately. Before the fish disease-prone season comes, you should try your best to feed it well, but you should not be overfed. 80% of the time is enough:

5. Strengthening oxygen enrichment measures adequate oxygen is a necessary condition for water quality stability and fish growth. In the process of fish culture, with the increase of culture time, the accumulation of bottom dirt in the culture pond makes heterotrophic bacteria at the bottom of the pond become the dominant flora, causing serious hypoxia at the bottom of the pond, resulting in the accumulation of nitrite and ammonia nitrogen due to incomplete oxidation (poisoning). The most serious consequence of anoxia at the bottom of the pool is the proliferation of disease-causing bacteria such as Aeromonas hydrophila and Vibrio, and hypoxia has significantly reduced the immunity of turtles, so it is easy to break out diseases. Therefore, in order to minimize the stock of dirt at the bottom, the dissolved oxygen must be high enough to dispel, oxidize and decompose the dirt, and to provide conditions for extensive contact with biodegradable dirt. The most effective means is to improve the water circulation and eliminate the bottom hypoxia. The method is to sprinkle 20000g / mu of sodium percarbonate as the main component of the oxygen enhancer in the whole pool on a sultry and rainy day and from 24:00 to 1 am at night. At the same time, continue to operate the aerator.

6. Strengthen the technology of water quality control grass carp species like to live in a cleaner water quality environment, so in the process of culture, a variety of measures should be taken to strengthen the regulation and management of water quality, especially in the middle and later stages of culture. due to the long-term accumulation of feeding amount, residual bait, fish feces and small biological carcasses, the sediment is further deteriorated, which is easy to induce fulminant diseases. Therefore, regular and quantitative sprinkling of photosynthetic bacteria, nitrifying bacteria, Bacillus, EM bacteria and other microecological agents and appropriate water exchange method are used to control water quality, maintain good water quality from beginning to end, improve dissolved oxygen, stabilize algae phase, reduce the fluctuation of pH, reduce the content of harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide, keep the water environment relatively stable, and make the beneficial bacteria in the water body become the dominant population. Inhibit the growth of harmful microorganisms, thereby reducing the growth of bacteria. The content of hydrogen and nitrogen in wrestling water is less than 0.5 mg / L, the content of nitrite is less than 0.05 mg / L, and the transparency of water is more than 30 cm.

7. Improve disease prevention measures and scientifically use disinfection drugs to improve the immunity and disease resistance of fish. In recent years, many applications have shown that the selection of Chinese herbal medicine or Chinese herbal medicine extracts such as Scutellaria baicalensis polysaccharide and ginsenoside immune growth promoters can improve the immune ability and disease resistance of fish. In view of the intermittent death in the process of two-year-old grass carp fingerling culture, Chinese herbal medicine bait composed of Coptis chinensis, Cortex Phellodendri, Radix Astragali, Radix Isatidis, etc. supplemented with Vc, VE and other drugs to protect the liver and protect the liver, at the same time, Sanbao high-stable vitamin c 150g / mu can be sprinkled per mu to improve the anti-stress ability of fish. The use of disinfectants should choose less irritating drugs, such as amino acid iodine, chlorine dioxide, bromochlorohydantoin and so on. prevent drug abuse, destroy water quality, and cause new stress to fish: the above are some basic measures to improve the survival rate of two-year-old grass carp fingerling. Because two-year-old grass carp species are often affected by density, environmental conditions, growth rate and other factors in the process of intensive culture in ponds, in order to improve their survival rate, we should make full use of beneficial biological agents to improve pond water quality and pond environment, strengthen pond oxygen enrichment measures and stress management, so as to make two-year-old grass carp species live in a comfortable environment, which is beneficial to their growth and improve the survival rate of two-year-old grass carp.