Freshwater White Shark (Pangasius sutchi) Farming Techniques and Feeding Management Key Points

The freshwater white shark is a tropical fish, with a suitable water temperature for growth of 20-36°C. When the water temperature drops to 14-18°C, its activity weakens and it may even stop feeding; when the water temperature falls below 12°C, it begins to die. It is suitable for farming in the south or in greenhouses and in warm water discharged from thermal power plants. pH value ~7.2. It tolerates low oxygen; the swim bladder is densely divided into numerous saccular respiratory chambers with highly developed capillaries, serving as an important accessory respiratory organ. It can breathe in air and has a strong tolerance to low oxygen. Its feeding habits are relatively omnivorous. Juveniles live on the bottom and feed on planktonic animals and plants, such as rotifers, flatworms, cladocerans or various algae, and can also consume artificial compound feed. Adults feed on aquatic plants and artificial feed, and also readily eat leftover rice, wheat bran, vegetable leaves and animal carcasses. It grows quickly. In northern China, fingerlings of the year can reach 0.5 kg-1 kg after 4-5 months of pond farming, while in the south they can reach 1-2 kg.
　　
I. Adult Fish Farming
1. Monoculture: Ponds of 1-5 mu are all suitable, with a water depth of 1-2 m. From April to May each year, when the water temperature reaches above 18°C, stock fry with a size of 5-10 cm at 1000-3000 fish per mu. Feed with artificial compound feed or small fish, small shrimp, rice bran, etc.
2. Polyculture: It can be polycultured with the four major Chinese carps, tilapia, shrimp and crabs, etc. Generally, stock 60-100 fish per mu, with a size of 5-10 cm. No additional feed is needed, and the pond water space can be fully utilized to increase yield and benefits.
3. Cage farming: For cages with a volume of 15-20 m3 of water, stock 50-150 fish per m3 with a body length of 8-10 cm. Generally, 60-100 kg of adult fish can be produced per cubic meter. Artificial compound feed must be used for feeding, with a protein content requirement of above 35%. The general survival rate of farming reaches 80%-90%, slightly lower than that of pond farming, which is related to the bottom-dwelling life of the freshwater white shark.
Daily management: At the fry stage, soybean milk, powdered compound feed, etc. can be splashed daily, 3-4 times a day. After one week, feeding can be switched to bloodworms, aquatic earthworms or artificial pellet feed. When feeding, achieve the "three observations," namely observing the weather, observing the water quality, and observing the fish's activity and feeding conditions; and the "four fixeds," namely fixed time, fixed place, fixed quality, and fixed quantity. Ensure they can eat their fill without waste, but this fish is very greedy, so overeating should also be avoided. Grasp the principles of fresh, tender, live, and suitable, maintain quality and quantity, and enable the shark to grow faster.
Various vitamins should be added to the feed, and allicin or drugs such as Yumiaoning and Yujiankang should be added to prevent the occurrence of diseases such as enteritis, skin rot and scabies. Regularly splash drugs such as bromochlorohydantoin and chlorine dioxide in the water body to prevent bacterial or viral diseases. In preventive drugs, try to avoid chemical drugs with relatively large side effects, such as potassium permanganate, formaldehyde, copper sulfate and malachite green. Because the shark has no scales and is highly sensitive to chemical drugs, more Chinese herbal medicines should be used for prevention and treatment.
　　
II. Fish Disease Prevention and Treatment:
1. Enteritis disease: Sick fish move slowly, do not eat, have a swollen abdomen, darkened body color, red and swollen anus. When pressing the abdomen gently by hand, yellow mucus flows out. When the abdominal cavity is opened, the coelomic fluid increases, the intestinal wall is congested and reddish-brown, and there is black mucus in the empty stomach. Sick fish die relatively quickly. For prevention and treatment, allicin can be used, adding 0.1-0.3 g per kg of feed for feeding; furazolidone can also be used at 0.2-0.3 g per kg of feed added for feeding; feeding with berberine hydrochloride is most effective. Disinfect the water body with dichlorohydantoin or bromooxychlorohydantoin every other day.
2. White spot disease: Also known as ichthyophthiriasis. On the fish's skin, fins or gills, individual white spots can be seen, and a large amount of mucus is secreted. Microscopic examination reveals Ichthyophthirius organisms. In addition, Trichodina, Gyrodactylus, Dactylogyrus, etc. may also parasitize. The drugs used can be 0.5 mg/L of splashed; or 4% Yuchongqing added to feed for feeding to expel the parasites. When choosing Yuchongmie, Shachongjing or trichlorfon, etc., attention should be paid to the dosage, as this fish is relatively sensitive to them, while the above-mentioned Chinese herbal preparations have relatively few side effects.
3. Gas bubble disease: When fertilizing for freshwater sharks, agricultural organic fertilizer easily produces gas bubbles. Under oxygen-saturated conditions, fry are very prone to gas bubble disease. Excessive ammonia nitrogen gas at the bottom of the pond can also cause gas bubble disease and lead to death.
Therefore, when fertilizing the water body, chemical fertilizers such as Feishuibao or a mixture of light fertilizer, phosphate fertilizer and potassium fertilizer should be selected. Pay attention to treating the pond bottom with Dijing, Anjing, etc. When oxygen is insufficient, appropriately select oxygen-increasing agents, and use or do not use oxygen-increasing pumps. Also pay attention to maintaining fresh, lively and refreshing water quality, which can effectively prevent the occurrence of this disease.
4. Gill rot disease: Symptoms are congestion and ulceration of the caudal fin, anal fin and dorsal fin. The cause is bacterial infection, which can cause mass death within two or three days and is common in fingerlings. The treatment method is to use 200 g per mu of Baiduqing per meter of water depth, splash over the whole pond, and use it twice in succession, with very good results.
Freshwater shark farming is simple, and the feed requirements are not high. Its chondroitin sulfate has relatively high medicinal value, the market value of commercial fish is high, and the economic benefits are significant. It is currently a relatively good new variety for farming famous, special and excellent fish in China.