Culture techniques of rainbow trout

1. Feeding and management of adult fish. Adult fish ponds can use soil ponds or cement ponds, soil ponds to about 1 mu, water depth of 1.5 meters is appropriate, cement ponds to about 50 square meters, water depth of about 1 meter is appropriate. It is best to set up a sewage outlet at the bottom of the pool to facilitate the frequent discharge of feces or waste bait. The mesh of the anti-escape mask should be 1 × 1 cm. If it is too large, it will escape the fish. If it is too small, it is easy to be blocked by leaves and moss. Clear the pool with lime before stocking. Free-range fish should be screened and neatly sized, with a weight of about 50 grams per tail. It should be kept reasonably and closely according to the conditions of water flow and dissolved oxygen. Generally, you can raise 1 kilogram (about 3 pounds) rainbow trout per liter. In feeding and management, we should focus on water, bait and disease. Water quality should be constantly updated, generally more than once an hour, but also regularly brush the pool, clear the pool, generally once a month. For ponds with high density or low water flow, oxygen-increasing equipment should be installed and the pool should be brushed frequently, usually once a month. The general animal composition of adult fish diet accounts for 30%-40%, the plant composition accounts for 70%-60%, the food should be fresh, the protein content of pellet feed should be 40%-42%, and the fat content should be 7%-9%. The carbohydrate content should be 9% to 12%. The daily feeding amount is 3%-5% of the body weight of fish, which is fed twice a day. Rainbow trout is easy to suffer from liver disease and enteritis at the stage of adult fish feeding, and the mortality rate is very high, so disease prevention should be done carefully. The growth cycle of rainbow trout commercial fish is generally from 1 year and 6 months to 1 year and 10 months. The specification is more than 300 grams. 2. The conditions of building the field. First of all, the water source and site must be selected. the water source can use cold spring water, reservoir bottom water, groundwater and so on, but the water temperature is kept at 7-20 ℃ all the year round. The amount of water should be abundant, the range of seasonal variation should be small, and the annual flow should be constant. If the annual variation is obvious, the planning should be based on the water flow in the dry season. About 100 litres of water per second can produce 20 tons of fish. The amount of dissolved oxygen in the water source should be more than 5 mg / L. Source water quality should also be carefully investigated, calcareous water is rich in natural bait, fresh water quality can be used to use swamp water, peat water is acidic should be abandoned. It is necessary to investigate whether there are nearby factories, mines and other wastes polluting the water source. After water quality analysis, dozens of fish species were used to test the water. The selection of the site should consider whether the soil quality is suitable, such as sand gravel bottom, black soil and loess bottom, and the topography should have a certain inclination, generally 1: 3 ∶ 1000, which is convenient for the construction of series pool, natural drop, water drop to increase oxygen, and convenient for sewage discharge. The water source should be higher than the water surface of the pool, so it can avoid mechanical pumping to save electricity and reduce expenses. The construction of the field must also consider whether there is a power supply nearby, so as to facilitate the erection of power lines and lighting lines, so as to mechanize the processing of bait, install aerators and so on. In addition, the nearby sources of bait, traffic conditions, and commercial conditions must also be considered. Prevention and treatment of common fish diseases: 1. Common fish diseases during ovalization. Mainly water mildew disease, this disease directly affects the hatching rate, water mold hyphae, not only infects the dead eggs, but also surrounds the eggs. Prevention and treatment methods: (1) pick out the dead eggs in time. (2) put the eggs in 1 / 200000 ~ 1 / 300000 malachite green solution and rinse for 30 minutes. (3) the eggs were immersed in formalin solution with a concentration of 5000 for 3 minutes. (4) disinfect the eggs with saline with a concentration of 10.5% to 11%. At the same time, the bad eggs can be separated. 2. Common fish diseases in seedling stage. (1) small melon worm. Symptoms: parasitic water surface, Gill, fin subcutaneous tissue, in the body surface and Gill can see many small white spots, making the fish restless and difficult to breathe. Prevention and treatment methods: the concentration of 0.3~0.4ppm malachite green was disinfected for 90 minutes, and in severe cases, 0.5ppm was used for 60 minutes, each course of treatment lasted 2-3 days. (2) the third generation worm. Symptoms: parasitic on the fish's gills, mouth, head, body surface, destruction of epidermal tissue makes the fish restless, poor diet, serious death. Prevention and treatment: when the water temperature is above 15 ℃, rinse for 30 minutes with the concentration of 1: 1000, 1: 5000, and with the concentration of 1, 000, 000 and 3000 when the water temperature is below 15 ℃, wash for 30 minutes. (3) enteritis. Symptoms: intestinal congestion and inflammation, no food, in severe cases, the intestines are full of pus. Prevention and control methods: utensils, processing feed machinery to keep clean, regular disinfection, do not feed deteriorated bait. Therefore, it is necessary to do a good job in keeping bait fresh. 3%-5% garlic was added to the feed and fed continuously for 3-6 days. 500 mg furazolidone was added to every 50 kg feed for 3 to 6 days. (4) rotifer. Symptoms: parasitic on the skin and gills of fish, poor diet and difficulty breathing of diseased fish. Prevention and treatment methods: copper sulfate or ferrous sulfate washing, the concentration is 4ppm (the ratio of the two is 5 ∶ 2) for 20 minutes. Malachite green leaching, concentration of 0.3~0.4ppm, once every other day for 3 times. 3. Common fish diseases in adult and parent fish stage. (1) planthopper. Symptoms: parasitic body surface, sucking fish blood, stabbing, irritating fish skin, causing wounds. Control method: 6% wettable BHC powder, sprinkled in the whole pool, the concentration is 1ppm. Refined trichlorfon 96%, the concentration is 1.5ppm, wash for 3 minutes for 4 hours, move into the new pool. (2) Hepatic steatosis. Liver disease is one of the main diseases of rainbow trout, which is very harmful, which is mainly caused by lack of nutrition or deterioration of feed. Once it occurs, it can cause a large number of deaths. The diseased fish have black body color, lighter Gill, anemia, yellow water in the anus, yellow mucus in the dissected viscera and yellowish liver. Prevention and treatment: due to long-term improper nutrition, this disease must start with improving nutritional conditions, pay attention to not eating feed containing oxidized fat, and feed fresh feed in time when fish disease is found.