Generally, there is no scale on the body, with a flat head and a big mouth, and there are several long whiskers around the mouth, which can distinguish the taste, which is its characteristic.
Nocturnal, quietly hiding in the pit at the bottom of the river or under the roots during the day. Large species that eat a lot, such as the Danube catfish, will attack small waterfowl or mice.
Catfish eggs are poisonous. Eating them by mistake will lead to vomiting, abdominal pain, diarrhea, dyspnea, and even paralysis in severe cases. Nutrition analysis editor This paragraph of Chinese medicine believes that catfish is sweet and warm, and has the effects of tonifying Yiyang, facilitating urination and treating edema.
Catfish is rich in nutrition, with water content of 64. 1 g and protein14.4g per100g of fish, and contains various minerals and trace elements, which is especially suitable for people with weakness and malnutrition.
Except that the roe of catfish has a bad taste and is not suitable for eating, the whole body is a treasure. Catfish is a valuable nutritional product, which has been recorded in history books for a long time and can be compared with shark's fin and wild turtle. Its dietotherapy and medicinal value are not available to other fish, and its unique functions of strengthening bones and prolonging life are its unique highlights.
Culture mode of Silurus meridionalis: pond culture
Pond culture can be divided into two types: polyculture in Dan Yanghe.
(1) The pond is single-cultured. The advantages of raising leather beard alone in pond are high yield, convenient management and convenient fishing and harvesting. The disadvantage is that the pond is not fully utilized and the production potential is not fully exerted.
① Pond conditions. The pond requires sufficient water source, no harmful substances, convenient drainage and irrigation, flat and firm bottom, silt thickness less than15cm, and firm ridge without holes. The ridge of the pond is more than 40 cm above the water surface, and the water inlet and outlet are blocked to prevent escape. Putting water lily or duckweed on the pond surface can not only shade, but also purify the water quality and serve as auxiliary feed. Before the fingerlings enter the pond, it is necessary to dry the pond, clean and disinfect it, apply base fertilizer, and inject new water. Only when the reproduction of feed organisms in the pond water reaches its peak can fingerlings be released.
Generally, the pond area is 600-2000m2, and the water depth is1-1.5m..
② Fish stocking. The specifications of the stocked fish species are consistent, and the stocking density depends on the size of the fish species and the conditions of ponds, feeds and water sources. Generally, about 5-10 fish species are released per square meter. Putting in large-scale fish species can improve the survival rate and increase the yield. The specifications of fish species in Xiatang should be no less than 5cm.
③ Feeding. When fingerlings just go into the pond, they should be fed some high-quality animal feed to restore their physique and accelerate their growth as soon as possible. Silurus meridionalis is an omnivorous fish that mainly feeds on animals, such as snails, clams, snails and other shellfish, as well as fly maggots, silkworm chrysalis, earthworms, animal carcasses and scraps. Shellfish should be broken and fed, and those with strong toughness should be broken or twisted into pulp to make food balls to improve utilization rate. Powdered feed (fish meal, bone meal, shrimp shell powder, corn meal, rice bran, wheat bran, etc.) is best mixed with meat for feeding. Conditionally, according to the nutritional needs of Silurus meridionalis, it can be prepared into granular feed with crude protein content above 30%, which can not only improve the utilization rate of feed but also accelerate the growth of fish. Feeding should be on the feed table. Feed should be fine and coarse, with 1 time in the morning, middle and evening every day, and the feeding should adhere to the "four decisions".
Proper application of organic fertilizer to cultivate zooplankton can meet the feeding needs of Silurus meridionalis and reduce the feed coefficient.
④ Daily management. Clean the feed table frequently to keep the water fresh and prevent the fish from lacking oxygen due to high density. Water should be filtered to avoid parasites and other enemies. It is also necessary to prevent snakes and rats from digging holes and rising water to escape fish after rain. Usually, we should check whether there are loopholes in the patrol pond and whether the fish-stopping facilities are damaged.
(2) Polyculture in ponds. Mixed culture of catfish with other fish can make full use of water space.
Suddenly, play the pond production potential. This method can also be used to remove wild fish in the pond and control the excessive reproduction of tilapia.
Silurus meridionalis can be mixed with chain, bighead carp, carp, grass, tilapia and other fish, but not with carnivorous fish. The specifications of mixed-culture fish species should be appropriately large, and it is best to meet the commodity specifications in the same year, and they can be put on the market together with the catfish. Polyculture methods are:
① Silurus meridionalis is the main species to raise other fish: generally, 3-6 Silurus meridionalis fingerlings of 5-6 cm per square meter are raised, and one domestic fingerling is raised every 2-3 square meters.
(2) Give priority to other fish, supplemented by catfish with leather beard: a catfish with a body length of 6-8 cm should be raised every 2-3 square meters in the adult fish pond where domestic fish can be fed, and small miscellaneous fish and aquatic insects in the water should be used as its feed, so there is no need to increase feeding.
(3) polyculture of Silurus meridionalis parent fish in adult fish ponds: a small amount of reproductive Silurus meridionalis is put in the ratio of male and female1:1or1.2, and put in fish nests for spawning and hatching in breeding season. According to the number of Silurus meridionalis, some animal feeding should be given properly, so that it can directly develop commercial fish in the adult fish pond. When stocking, the carrying capacity of the water body after the breeding of Silurus meridionalis should be considered.
Prevention and control techniques of fish diseases in Silurus meridionalis
(A) blackbody disease
The diseased fish became black, emaciated and stopped eating. In severe cases, the fish often hung on the surface of the water with its head up until it died. After examination, there is a round red blood spot on the inner side of pectoral fin, the fin is ulcerated, and mildew spots appear on the back of its head. This disease is easy to be infected in the fry stage, and it is most prone to disease due to insufficient bait and poor water quality, with rapid onset and rapid infection.
Prevention and control methods: keep the water clean and do not use unfermented fertilizer; Galla Chinensis 2-4g/m3 is splashed all over the pool, and 30g/L quicklime water is splashed all over the pool, once every other day, for 2-3 times.
(2) Enteritis
The diseased fish is emaciated and black, its abdomen is swollen, it swims alone, lightly presses its abdomen, and there is light yellow mucus flowing out of the anus. Abdominal hydrops, congestion and inflammation of the intestinal wall, reddish purple, especially in the posterior intestine, and ulceration and shedding of intestinal mucosa can be seen by laparotomy. The disease is caused by bacteria or viruses, which mostly occurs in July and August, and mainly harms fish species and adults.
Prevention and control methods: hanging baskets with bleaching powder in the onset season; Sprinkle with 1 g/m3 bleaching powder in the whole pool for 2 days; Every kilogram of fish is mixed with 1 mg furazolidone for 1 week, plus1.4-3 mg/liter of gallnut is sprinkled once; Every 50 kilograms of fish were fed with sulfaguanidine according to17.5 grams of medicine for 6 days, and then sprinkled with bleaching powder.
(3) Bubble disease
The sick fish floats on the water, with its abdomen facing the sky, and there is a bubble in its abdomen, so it can't sink. The main cause of the disease is that too much unfermented organic fertilizer is applied in the pond, or the water quality in the pond is aging, and there are too many blue and green algae in the water, which makes the gas in the water too saturated under strong light and causes fish to eat bubbles by mistake.
Prevention and control methods: when the transparency of the pool water is too small, it is not suitable to put fry; Injecting fresh water quickly after onset and feeding enough live bait can make some fry discharge bubbles and return to normal; For every water depth 1 m, sprinkling1.5-2kg of salt on the whole pond after water has certain curative effect.
(4) Water mold
After the infected fish was infected with water mold, gray-white mass hyphae appeared on its body surface, which was like cotton wool. After the mycelium gradually expanded, the fish swam abnormally, the skin mucus increased, the appetite decreased, and finally lost weight and died. Most of the causes are injuries during fishing and transportation, or frostbite at low temperature.
Prevention and control methods: pay attention to the operation, do not hurt the fish, and control the water temperature in the overwintering pool above 15℃; Soak fish bodies or eggs with10g malachite green per cubic meter; Soak the sick fish10-20 minutes with 3%-4% salt solution; Each milliliter is sprinkled with 1 mg bleaching powder in the whole pool; Sprinkle the mixture of 0.4 ‰ salt and 0.4 ‰ baking soda in the whole pool.
(5) Wheel disease
The large rotifer parasitizes on the skin and fins, causing the body to be black, thin and slow to swim. Small rotifers gather in the edges and crevices of gills, constantly sliding on the gills, stimulating gill tissues, and in severe cases, turning the edges of gill filaments white and rotten, making sick fish dark and emaciated, and swimming slowly away from the pool. The growth and development of young fish are hindered or even died when a large number of parasites are present.
Prevention and control methods: thoroughly clean the pond with quicklime, and do not use unfermented organic fertilizer; When the seedlings are separated into ponds, transferred to ponds and overwintering, they should be soaked with 8 mg/L copper sulfate; Use 0.7 g/m3 mixture of copper sulfate and ferrous sulfate (5: 2) to sprinkle all over the pool.
(6) Cercosporiasis
Sarcocystis sinensis parasitizes fish fins and skin, causing gray-white punctate nodules or blocks in fish bodies. It mainly harms the seedlings cultivated in soil ponds and spreads in the form of spores. The popular season is May-July.
Prevention and control methods: remove excessive silt; Using quicklime can kill spores in silt; Spray with 0.3-1g/m3 of crystal trichlorfon.
(7) Third-generation worm disease
Due to the movement of the third generation of parasitic worms, the body surface and gill filaments of the fish are damaged, which makes the fish secrete gray-white sticky liquid surface, which can cause mass death when it is seriously infected. The disease mainly harms the young Silurus meridionalis cultured in soil ponds and spreads by host or current. It is popular when the water temperature is around 20℃.
Control method: Dip and wash the fish with 2-3g/m3 trichlorfon when entering the pond; 90% of crystal trichlorfon is spread all over the pool at 0.2-0.3g/m3; Use 0.1-0.24g/m3 mixture of trichlorfon and surface alkali (ratio of 5: 3) to spray it all over the pond.