1, clear pond, cultivate water The pond used to cultivate bass should be dried, dredged and exposed to the sun, especially the old pond that has been cultivated for many years. Disinfect once half a month before the seedlings are released, and apply 50 kilograms of quicklime per mu or use 20PPM bleaching powder with appropriate pool water for disinfection. If it has not been exposed to the sun in the dry pond, it is necessary to use 30 kilograms of tea bran per mu to break it and soak it all over the pond, so as to completely remove the fierce miscellaneous fish left behind. After disinfection, the pond is filtered with fresh water, and 3 kilograms of compound fertilizer is applied per mu to cultivate plankton. If the water quality is slightly green or brown, seedlings can be cast.
2. The density of seeding has reached10cm, and it is better to stock 2,500 fish per mu, and the yield per mu can reach1200-1500kg in the 300-day cultivation period. If the seedlings are planted too closely, the pond will be prone to aging and fish diseases, and it is difficult to carry out sustainable production.
Because there are many baits in high-density culture, and perch rarely seek the leftover bait at the bottom of the pond, it is necessary to put 100 crucian carp and 30 silver carp and silver carp per mu to reduce the water pollution and increase the culture efficiency.
3. Feeding perch for overeating and properly controlling the feeding amount will help to reduce the cost, the occurrence of gastrointestinal diseases and the pollution of water quality. Feeding should be timed, fixed-point and quantitative. Generally, two meals are fed daily, at 7-9 am and 4-6 pm respectively, and the daily feeding amount is about 5% of the fish weight. It is necessary to adhere to the habit of taming food, build a bait bridge in the pond, tap the bait bridge or splash the pond water every time, and call the fish to swim for food, which is beneficial to observe the feeding and health status of the fish and facilitate the adoption of contingency measures. Perch grabs the suspended feed in the water and stops eating after sinking, so small miscellaneous fish should be fed patiently and slowly, while floating feed should be used for granular feed.
4. Water quality management High-yield culture of perch is also high-density culture. It is very important to keep the water fresh and dissolved oxygen sufficient. The main methods are: changing water frequently, especially in the middle and late stages, and the daily water exchange rate should reach more than 30%; Increase oxygen frequently, the aerator can be started properly during the fry period, and the frequency of starting the aerator becomes more and more frequent with the growth of the fish, especially in high temperature weather and the later stage of culture, some aerators can be started at night, and all aerators should be started during the day to keep the dissolved oxygen in the pond water above 5 mg/L; Applying biological agents, high-density culture brings a lot of residual bait and excrement at the bottom of the pond, and the decomposition concentration of harmful substances is high, which consumes a lot of oxygen in the water, especially in high temperature weather, which is an important cause of fish diseases. Appropriate application of biological agents allows beneficial bacteria to remove ammonia nitrogen and nitrite from the water and maintain good water quality.
Disease control
1, ammonia nitrogen poisoning In hot weather, the ammonia nitrogen in the water is high, and even nitrite is produced, resulting in the death of perch due to hypoxia poisoning. The main symptoms: the fish are restless in the whole pond, scurrying up and down, the fins are congested and the gills are dark red. Prevention and control methods: immediately inject new water and release old water, and pay attention to blocking the water with wooden boards when injecting water, so as not to directly flush the dirt at the bottom of the pond and accelerate the death of fish; Apply fluorspar powder (bottom treatment agent)10-15 kg per mu to neutralize ammonia nitrogen in water; Pay attention to the prevention with biological agents before the onset.
2. The fish with enteritis has low appetite, swollen abdomen, red and swollen anus, and yellow mucus can flow out under light pressure, which can occur all year round. The preventive measure is not to feed spoiled small miscellaneous fish. Treatment: 300 grams of furosemide mixture is mixed into each 100 kg of surimi and fed continuously for 3-5 days.
3, rotten gill disease This disease is easy to break out and has a high mortality rate. The main symptoms: the fish is black, especially in the head, swimming slowly, unresponsive to external stimuli, dyspnea, loss of appetite, increased mucus in the gills, swollen gill filaments, terminal erosion, emaciation, straying, and finally death. Treatment: every 100 kg of fish is fed with 6-8 grams of compound sulfamethoxazole and 4-6 grams of chloramphenicol for 3 days.
4. Rotifers, Trichinella spiralis and Polyconchocerciasis mostly occur on the body surface and gill filaments of fish in the intermediate culture stage. The symptoms are emaciation, blackening and mouth erosion of fish, which occur all year round. In prevention, a large number of water changes are used to improve water quality. 0.7-1ppm mixture of copper sulfate and ferrous sulfate (5: 2) can be sprayed evenly in the whole pond, or 20-25 ppm formalin can be sprayed in the whole pond.
5, red skin disease, canker disease, the base of the fin is congested, red and swollen, scaling, epidermis rot, muscle exposure. This disease mostly occurs in the high temperature season, so it can be prevented by replacing a lot of fresh water, regularly applying 35-40 ppm of quicklime, and exposing to the sun in dry ponds in winter. Bleaching powder 1ppm can be used for treatment in the whole pond; Oral furosemide mixture, 300 grams per 100 kg surimi; Intramuscular injection of penicillin, 3000 international units per kilogram of body weight.
6. Fish-sole disease Fish-sole parasitizes the gills, skin and fins of fish, causing proliferation and deformation of gill epithelium, inflammatory edema and body surface damage, causing secondary bacterial infection and death. Treatment: Spraying crystal trichlorfon 0.2-0.3 ppm in the whole pond.