Freshwater whitefish breeding technology

Freshwater white peony is popular among farmers because of its advantages of good meat quality, fast growing speed, easy to grow and manage, and large market sales. However, due to the warm fresh water fish, the optimum temperature for growth is 15-30°C. When the water temperature is lower than 12°C or higher than 36°C, it will cause death. Therefore, freshwater white bream seedlings should grasp the following technical points over winter. 1. Site selection The ponds that are selected for wintering should be able to maintain a water depth of more than 1.5 meters. The minimum water temperature (in January) can be maintained above 12 degrees Celsius, with an area of ​​1,000 to 2,000 square meters. The water source is convenient, and there is sufficient sunshine to avoid the north wind. The venue is better. 2. An ordinary pond (ie, a pond with no hot spring water) is installed in a cold-proof shed, and a cold-proof shed must be installed in winter. At present, most farmers use a small galvanized steel pipe and angle iron to make a half moon shape, which is fixed on a pond bank and then covered with a nylon film on the shelf. Cold shelters are generally built near the pond to the north, and the shed area accounts for approximately 1/2 to 2/3 of the whole pond. And put some straw under the cold shelter. In this way, when the cold wave strikes, the fry can be gathered in the thick grass to warm up. The main purpose of the above measures is to prevent hail or snow from falling into the fish pond directly in the rain and snow, and to cause fish to be injured and injured. 3. Daily feeding and management During the wintering period (ie from late November to late February of the following year), the feeding and management of freshwater pelicans will directly affect the survival rate and overall economic efficiency of the spring plague. Therefore, management should pay attention to: (1) feed feeding. When the water temperature is above 20°C, the daily feeding amount of the feed should be 4% to 5% of the fish's body weight, which should be fed in the afternoon; generally, peanut bran or feed containing more than 30% of crude protein should be used after soaking. When the water temperature is around 15 ~ 20 °C, the daily feeding amount of 2% to 3% of the fish body weight can be fed in the afternoon. Water temperature below 15 °C do not have to feed. The feed should be fed in a fixed position in the cold shelter, timing, positioning, qualitative, quantitative delivery. (2) Water quality management. Due to the low temperature in the winter, the metabolism in the pond is slow, so the water in the pond tends to become clear and often has a transparency of more than 30 cm. At this time, some chicken manure or pig manure should be properly put into the pond to make the water quality “green, tender, and cool”; the transparency can be about 20 cm. 4. Disease control The diseases that are more harmful during the overwintering period of freshwater whitefish are mainly watery mildew and small melon worm. (1) Shui mold. Because of the mechanical damage or frostbite of the fish, the disease caused by water-borne fungus spores invades the wound and absorbs nutrients from the fish skin to grow rapidly. The end of the mycelium is absorbed like a tree root in the skin tissue of the fish, and most of the rest is exposed in the body. Outside the table. The water hyphae hyphae floats in the water like white cotton wool and is visible to the naked eye. After the fish parasitizes the aquatic fungus, it will show irritability, because the mycelium absorbs the tissue nutrition in the epidermis of the fish, and the bacteria infects the wound, causing the necrosis of the epidermis, and the diseased fish will die due to the thinness. Control methods: 1 Before the fry is released, clear the pond thoroughly with quick lime to reduce the incidence of this disease. 2 Care must be taken to ensure that the fish is not injured when pulling on the net and fishing operations. There are individual fish frostbite in winter and snowy days. Do not fish in the pond and disturb the fish. 3 0.1 mg/kg potassium permanganate solution Quanchiposa, the other day, 2 times can be. (2) Small melon worms. There are many small white spots on the surface of the diseased fish, which can secrete large amounts of mucus on the surface of the fish and form cysts in the parasitic parts. If the pathogens are parasitic on the cornea, it can lead to blindness of the fish. The diseased fish appear restless and clustered. Swimming around the pool, and constantly rubbing against other objects or jumping out of the water, the fish was thin, black, reeling, breathing difficulties, and soon died. The pathogen of the small melon plague is the multi-small melon insect, suitable for the growth and development of the water temperature of 15 ~ 25 °C. Control methods: (1) Ponds should be thoroughly disinfected with quicklime, and concrete pools, glass containers, and plastic containers should also be disinfected with potassium permanganate or bleaching powder. 2 can be used dry pepper and dry ginger treatment. Each 667 square meters of water is 1 meter deep can be used 100 grams of dried ginger, add 500 to 1000 grams of water, boil for 10 minutes, then stop the fire for 20 to 30 minutes; then, boil for 10 minutes, and then stop the fire for half an hour; Add 250 grams of dried chili and 2000 grams of clear water, and boil for 10 minutes. Finally, even the slag with juice on the whole pool of 10 kg of water evenly spilled once a day for 2 days to cure. (4) Other matters. During the wintering season of freshwater pelicans, try not to interfere with the fish in the pool to avoid bruises; use of drugs such as trichlorfon is strictly prohibited; otherwise, the whole pool will die and the loss will be irretrievable. 5. Open spring management When the water temperature is stable above 20°C, the appetite of the freshwater fishy beetle begins to increase. At this time, concentrate feed and appropriate green feed should be added. The general concentrate feed mainly consists of peanut bran or soybean flour or compound feeds containing more than 30% crude protein. The daily feed accounts for approximately 4% of the fish's body weight; the green feed is fed with pasture, and the daily feed accounts for 20 of the fish's body weight. About %; usually the green material is fed in the morning and the concentrate is fed in the afternoon. In addition, the amount of fresh water injected into the pond will keep the water “green, tender, and cool”, which is beneficial to the growth and development of the white puffer fish seedlings.

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