Culture technology of freshwater white shark

Freshwater white shark belongs to tropical fish, and the suitable water temperature for growth is 20-36 ℃. When the water temperature drops to 14-18 ℃, the activity weakens or even stops feeding, and when the water temperature is lower than 12 ℃, it begins to die. It is suitable for hot water culture in the south or greenhouse and thermal power plants. Ph value is ~ 7.2. Resistant to hypoxia, the fat is densely separated into a large number of vesicular respiratory chambers, and highly capillarized, is an important auxiliary respiratory organ, can breathe in the air, and has a strong tolerance to hypoxia. The feeding habits of young fish are miscellaneous, and young fish live in benthic life, using phytoplankton and plants as bait, such as rotifers, flatworms, cladocera or various algae, as well as artificial feed for adult fish. They also like to eat leftovers, wheat bran, vegetable leaves and animal carcasses. The growth is fast. In the north of China, the fish species can grow to 0.5kg~1kg after 4-5 months of pond culture in that year, and 1~2kg can be reached in the south. 1, adult fish culture 1, monoculture: the pond can be 5 mu, the water depth is 1 mi 2 meters, every year from April to May, when the water temperature reaches more than 18 ℃, the fry with a specification of 5 mi 10 cm is released, with 1,000,000 fry per mu. Feed with artificial formula feed or small fish, shrimp, rice bran, etc. 2. Mixed culture: it can be mixed with four major domestic fish, tilapia, shrimp and crabs. Generally, there are 100 fish per mu, with a specification of 510cm. There is no need for additional feeding, which can make full use of the water space in the pond and improve the yield and efficiency. 3. Cage culture: a cage with a volume of 15-20m3 water body. The fish species with a length of 8 Mel 10 cm are 50 Mel 150 fish / m3, and generally can produce 100 kg adult fish per cubic meter. Must be fed with artificial formula feed, the protein content is required to be more than 35%. Generally, the survival rate of aquaculture reaches 80% Mel 90%, which is slightly lower than that of pond culture, which is related to the benthic life of freshwater white sharks. Daily management: soya-bean milk and powdered formula feed can be sprinkled every day in the seedling stage, 3 mi 4 times a day, and red worms, water earthworms or artificial granules can be used after weeks. Do three things when feeding, that is, look at the weather, water quality, and the eating of fish activities; four fixed, that is, timing, fixed point, qualitative and quantitative. To be full and not wasted, but the fish is gluttonous, and we should avoid overeating, grasp the principles of freshness, tenderness, liveliness and fitness, ensure quality and quantity, and make sharks grow faster. Various vitamins should be added to the feed, and allicin or fish fry ning, fish health and other drugs should be added to prevent enteritis, rotten skin, scabies and other diseases. Regularly sprinkle bromochlorohydantoin, chlorine dioxide and other drugs in the water to prevent the occurrence of bacterial or viral diseases. In preventive drugs, chemicals with greater side effects should be avoided as far as possible, such as potassium permanganate, formaldehyde, copper fluidic acid, malachite green and so on. Because sharks do not have scales and are sensitive to chemical drugs, more Chinese herbal medicine should be used for prevention and treatment. 2. Prevention and treatment of fish disease: 1. Enteritis: diseased fish act slowly, do not eat, abdominal swelling, blackening of body color, red and swollen anus, gently pressing the abdomen with hands, yellow mucus outflow, abdominal incision, increase of body fluid, intestinal wall hyperemia, reddish brown, black mucus on an empty stomach, rapid death of diseased fish, allicin can be used for prevention and treatment, 0.10.3g per kilogram of feed is added. It can also be fed with 0.2ml 0.3 g / kg feed: berberine hydrochloride is the most effective. Disinfect the water with dichlorohydantoin or bromooxyhydantoin every other day. 2. White spot disease: also known as melon disease. In the fish skin, fins, or gills, can be seen one by one white spots, and secrete a large amount of mucus, microscopic examination can be seen small melon worm body. In addition, rotifers, third-generation worms and ring worms may be parasitized. The medicine used can be sprinkled with 0.5 mg / L of deworming essence: or 4% of Yuchongqing is added to the feed to drive the insecticidal body, and attention should be paid to the dosage of fishworm, insecticidal or trichlorfon. The fish is more sensitive to it and has less side effects on the above-mentioned traditional Chinese medicine preparations. 3. Bubble disease: when applying fertilizer to freshwater sharks, agricultural organic fertilizer is easy to produce bubbles. Under the condition of oxygen saturation, seedlings are easy to cause bubble disease, and too much ammonia nitrogen at the bottom of the pool will also cause bubble disease and make them die. Therefore, chemical fertilizers such as Feishuibao or light fertilizer, phosphate fertilizer and potash fertilizer mixture should be selected for fertilization in the water body. Pay attention to the treatment of bottom net and ammonia net at the bottom of the pool, choose the right amount of oxygenator during hypoxia, and use little or no oxygen pump. And pay attention to keep the water quality fresh and lively, which can effectively prevent the occurrence of the disease. 4. Rotten mumps: the symptoms are congestion and ulceration of caudal, anal and dorsal fins. The disease is caused by bacterial infection, which can cause a large number of deaths within two or three days. Fish species are common. The treatment method is to use Baiduqing 200g/ mu per meter of water depth, the whole pool is covered with wine, and the effect is very good. The breeding of freshwater sharks is simple and the requirement of feed is not high. Its acid chondroitin has high medicinal value, high market value of commercial fish and remarkable economic benefits. it is a good new species of famous and special fish culture in our country at present.