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Efficient bait breeding of astragalus membranaceus

Huang Wei, also known as Huang Latin and Gayu, is a small freshwater economic fish. It is omnivorous, adaptable, low in water quality requirements and easy to introduce and domesticate. Because of its high nutritional value, it is favored by consumers more and more, and it is also an excellent variety suitable for eating and fishing to improve the structure of cultured varieties. In recent years, we have been conducting experiments on the main cultivation of small ponds, and all of them have achieved good results. Now, the key techniques of feeding Astragalus membranaceus in small ponds are introduced as follows:

1, bait preparation

The food in natural waters is mainly shrimp, fish and fish eggs, and some aquatic insects. Aquatic plants and so on. , so you can use fresh animal bait for artificial breeding. In recent years, we have domesticated and raised with self-made compound bait. The bait is made of imported feed additives such as fish meal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worm, etc. The early protein content is above 34% and the fat content is 4%. In the later stage, some imported fish meal can be replaced by small miscellaneous fish meal, with protein content of 30% and fat content of 6%. The bait must be fresh and free from mildew and rancidity.

Step 2 educate

Wild astragalus likes to eat during the day and at night. Domesticated for 5-7 days under artificial breeding conditions, you can completely feed on the bait table during the day. After staying in the pond for two days, the seedlings were domesticated by artificial feeding, and there was a fixed feeding signal during domestication, and fixed-point and fixed-time feeding training was carried out. After the patient is domesticated for 5-7 days, he can eat normally; Domesticated fry released in this way can be fed normally the next day after entering the pond, and the feeding methods can be manual feeding and mechanical feeding.

3. Feeding amount

The whole feeding process should be divided into three stages. In the first stage, feed 4 times a day in May and June, and the daily feeding rate is 3%-5%; In the second stage, feed it three times a day in July, August and September, and the feeding rate is 2%-3%; In the third stage, after 10, feed twice a day, with a feeding rate of 2%. On this basis, the feeding amount should be adjusted according to the weather and water quality. In the first and third stages, it is suggested to adopt the satiety method, that is, 90% of the fish on the bait will stop eating after leaving the table; In the second stage, because the weather is hot and the water quality fluctuates easily, it is recommended to feed "90% full", that is, stop feeding after 80% of the fish on the bait leave Taiwan.

In addition, due to the large mouth crack of Pelteobagrus fulvidraco, the particle size of bait should be increased accordingly. With the particle size of 2.0 mm as the open feed, the particle size of adult fish feed can reach more than 5 mm When it is required to use sunken hard granule bait, the granules should be stable in water for 15 minutes. Using floating bait will better improve the utilization rate of bait.

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Intensive culture technology of Pelteobagrus fulvidraco in pond

Pelteobagrus fulvidraco is a catfish. Family, Pelteobagrus. Some places are also called yellow Latin, yellow duck aunt, yellow fin fish, Japanese catfish and so on. It has gorgeous body color, tender and delicious meat, rich nutrition, high edible rate, strong vitality and wide temperature range, so it is a new variety that can be developed. Its biological characteristics and intensive pond culture technology are introduced as follows:

I. Biological characteristics

1. Morphological characteristics: long body length, wide and flat head, raised back, flat abdomen, slightly flat back, thick and short tail handle, big mouth crack, shorter jaw than upper jaw, fine teeth on upper jaw, 4 pairs of whiskers, small side eyes, hard spines on dorsal fin and pectoral fin, serrated upper jaw, slightly fan-shaped pectoral fin, near ventral fin at the end, and deeply forked caudal fin.

2. Feeding habits: It belongs to omnivorous fish, and its food includes all kinds of aquatic insects, small fish and shrimp, small mollusks and other invertebrates.

3. Growth and reproduction: Under natural conditions, the body length of 1 year-old fish can reach 8cm, the second-year-old fish can reach 16 ~ 20 cm, and the largest individual can reach more than 500 g. Generally, the second-year-old fish is mature, and the sexual mature individuals is generally more male than female. The spawning period is from May to July, and it is a perennial spawning type. During the reproductive period, males have the habit of nesting and protecting their eggs and larvae. The suitable breeding water temperature is 23 ~ 30℃, and the spawning amount of each tail is 2000 ~ 3600, which usually spawns at night. The fertilized egg is slightly yellow and sticky, the egg diameter is about 2 mm, the water temperature is 23 ~ 28℃, and it can emerge after hatching for 50 ~ 60 hours.

Second, pond culture technology

1. Pond preparation: Generally, the pond for culturing Pelteobagrus fulvidraco is 2000~3500m2, and the bottom of the pond should be flat, but the end of the drain should be slightly lower than the end of the water inlet (the slope should not be too large). Dig a fish collecting pit with a depth of 50 ~ 60m2 and a depth of 20 ~ 40cm for dry pond fishing; It is required that the pond has sufficient water, fresh water quality, convenient access to water, and the water depth can be kept at 1.5 ~ 2m. The planned output is above 150kg/667m2, and 1 2kw aerator is required; Remove excessive silt and keep it about10 cm; Clean the pond with 150kg quicklime every 667m2 water surface, mix lime into the bottom mud as much as possible, and inject water after 80cm exposure 1 week; Applying 100 ~ 200 kg fermented organic fertilizer every 667m2 can release fish species after cultivating a large number of plankton.

2. Fish stocking: The stocking time is generally from March to April, and the stocking density can be flexibly controlled according to the pond conditions, management level, feed and expected specifications. Fish should be individually stocked, with neat specifications, bright colors, smooth surface and strong physique. Generally, 2,000 ~ 4,000 Astragalus seedlings with a length of 5cm are stocked in 667m2, with about 30g per 667m21500 ~ 3,000 seedlings. Soak the fish 10 ~ 15 minutes with 5% salt solution before stocking, and try to avoid using strong oxidizing drugs such as potassium permanganate. After stocking Pelteobagrus fulvidraco 15 ~ 20 days, 200 ~ 400 silver carp with body length 10 ~ 15 cm were stocked on every 667m2 water surface.

3. Feed feeding: Under the condition of artificial feeding, fish, shrimp and animal scraps can be fed, or fish meal, meat and bone meal, blood meal, soybean meal and feed additives can be made into granular feed for feeding. Protein content is 30% ~ 40%, and fat content is 4% ~ 6%. Appropriate amount of zinc bacitracin can be added in high temperature season, which can effectively prevent and treat various diseases, alleviate various stress phenomena, promote growth and reduce feed coefficient. However, it should be noted that it cannot be used with colistin sulfate and furazolidone at the same time. Wild Pelteobagrus fulvidraco likes to feed at night, and it can feed normally in groups after 5 ~ 7 days of domestication. If the released fish species are artificially propagated, they can be fed normally the next day after entering the pond. After normal eating, the feeding rate is 1% ~ 3% before April, and 4% ~ 6% in peak season. Feed 1 time every morning and evening. Feed feeding should be "four fixed".

4. Daily management: In the process of Pelteobagrus fulvidraco culture, water quality management is the key. May-June monthly water injection 1 time, with a depth of 30cm, and June-September monthly water injection 1 time, with a depth of 20cm. Spray 15g/m3 quicklime once a month in hot season, and start the aerator at the right time. Pay attention to patrol the pond at ordinary times, observe and salvage weeds and dirt, and make records. Pelteobagrus fulvidraco is a scaleless fish with low tolerance to commonly used drugs, so high-efficiency and low-toxicity drugs should be used to prevent and treat fish diseases as much as possible. This species is sensitive to malachite green, copper sulfate, trichlorfon, potassium permanganate and other drugs, so use it with caution.

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Biology and artificial culture technology of Pelteobagrus fulvidraco

First, the development prospect of Pelteobagrus fulvidraco culture

Pelteobagrus fulvidraco is tender, delicious and nutritious. According to the analysis, the edible part of Pelteobagrus fulvidraco contains protein 16. 1 g, fat 2. 1 g, carbohydrate 2.3g, calcium154mg, 504mg. Phosphorus, which contains various essential amino acids, especially glutamic acid and lysine. According to medical history books, Pelteobagrus fulvidraco has anti-inflammatory and analgesic effects.

Second, biological characteristics of Pelteobagrus fulvidraco

Classification is status.

Pelteobagrus fulvdrace (Richardson) is a kind of freshwater economic fish widely distributed in freshwater bodies in China, commonly known as Gayazi, Yellow Labing, Yellow Whiskers and so on. , named Pelteobagrus fulvidraco in English, belongs to Silurian order, Lepidoptera and Pelteobagrus fulvidraco in fish classification. There are four species in this genus: Pelteobagrus fulvidraco, Pelteobagrus fulvidraco (Pelteobagrus vachelli), Pelteobagrus fulvidraco and Pelteobagrus fulvidraco. At present, the main breeding object is Pelteobagrus fulvidraco, followed by Pelteobagrus fulvidraco (both species have fry, and the latter two species have little breeding value because of their small size).

(2) Living habits

Pelteobagrus fulvidraco belongs to benthic fishes. Baitianxi lives at the bottom of the water body and swims to the top of the water body for food at night, which has strong adaptability to ecological and environmental conditions. According to relevant data, when the water temperature is 28-29℃, the average oxygen consumption rate is 0. 14 1mg/h, and the ventricular resting point is 0.314 mg/l, which has strong adaptability in anoxic environment. The temperature is low in winter, even if you leave the water for a few hours (as long as you keep a certain humidity). Still alive. Sometimes in late autumn and early winter, when people transport Pelteobagrus fulvidraco to the market for a short distance, they will use a layer of water grass at the bottom of the bamboo basket, then put Pelteobagrus fulvidraco on it, and then put water grass on it to keep it moist for transportation. After a few hours, all the inflatable fish put into the temporary breeding pond on the market can survive. Pelteobagrus fulvidraco often lives in an environment with slow river flow and rocky or pebbles, and overwinters in rivers, lakes, caves and crevices with low temperature in autumn and winter, with a small range of activities and difficult fishing. In mid-spring, they began to leave their wintering places and eat in nearby rocky shoals and rocks. During the day, they mainly live in rocks or pebbles with deep water, and at night they swim to shallow rocks to hunt. At dawn, they often see Pelteobagrus fulvidraco rushing to caves and cracks. When the water in rivers, lakes and reservoirs rises in summer, the water becomes turbid. During this period, Pelteobagrus fulvidraco mostly swam to wide troughs to feed on mosquito larvae brought or bred by water bodies. With the clarity of rivers and lakes and the drop of water temperature, it gradually swam to deep caves of rocky rivers and lakes with deep water depth to feed. Pelteobagrus fulvidraco likes gathering, foraging and moving in weak light.

(3) Feeding habits

Pelteobagrus fulvidraco is an omnivorous fish, and the feeding habits of Pelteobagrus fulvidraco with different individual sizes are significantly different. From the 4th to 5th day after hatching, zooplankton, such as rotifers, copepods, cladocera, etc., were fed artificially with feed such as egg yolk. It is 5-8 cm long, and its main foods are cladocera, copepods, chironomid larvae, earthworms and artificial compound feed (fish paste and plant feed mixture). The main foods whose body length exceeds 10cm are snails, shrimps, small fish, chironomid larvae, mayfly larvae, COLEOPTERA larvae, insect eggs, green water spiders, bitter leaves, POTAMOGETON malayi leaves, fibrous roots and debris of plants, fish scales, silt and other fish eggs produced on aquatic plants and stones. Under the condition of artificial feeding in ponds, in addition to feeding natural bait organisms in ponds, artificially prepared soft compound bait, hard pellet feed and floating feed are generally needed, especially under the condition of intensive cage running water feeding, the protein content of compound bait must reach 35-40%.

Third, adult fish culture.

The commercial fish culture of Pelteobagrus fulvidraco is called adult fish culture, which refers to the production process of raising commercial fish with more than 2cm fish species. At present, most of the commercial fish sold in China's market come from natural water bodies, and some of them are obtained from adult fish ponds. In recent years, many experts (including experts in this field) began to actively carry out the research on the main culture and polyculture of Pelteobagrus fulvidraco in artificial ponds, and obtained a series of mature technical data, especially in the large-scale artificial propagation of fry, which eased the contradiction of tight supply of fry. The experimental study shows that Astragalus membranaceus is suitable to be raised in ponds, cages, lakes, rice fields and other water bodies, and can be mainly mixed with silver carp, bighead carp, bream and grass carp. But it is not suitable for mixed eating with carp and crucian carp, because their eating habits are basically the same, which is easy to have adverse effects.

(1) Pelteobagrus fulvidraco is mainly cultured in ponds.

Pond culture is a new way of culture in recent two years. Pond culture has the characteristics of small investment, unlimited area, large income and stable production.

1. Pond conditions

(1) Water source and water quality The main culture of Pelteobagrus fulvidraco in ponds requires sufficient water source, and the water quality conforms to the water quality standard for fishery use, and does not contain substances harmful to fish. It is best to choose fish ponds near reservoirs, lakes, rivers and ditches, or fish ponds equipped with aerators, pumps and other mechanical equipment for the main breeding of Pelteobagrus fulvidraco. The main culture density in the pond is high, and the water quality is easy to deteriorate due to the low dissolved oxygen in the pond, which leads to the floating head of fish and a large number of deaths. If conditions permit, fresh water with high oxygen content can be injected frequently, which can not only improve the water quality of the pond, but also be beneficial to the reproduction of natural bait for fish and the growth of fish.

② The fish pond area, water depth and sediment of Pelteobagrus fulvidraco are not strict with the adult fish culture pond, and all fish ponds can be used for adult fish culture. It is best to choose a pond whose bottom at the outlet of the pond is deeper than other places 10%-20%, which is mainly convenient for fishing in the dry pond of commercial fish, and each pond must have controllable water inlet and outlet. Generally, the main pond area is 3-5 mu or less than 10 mu. The water depth of 1.5-2.0m is ideal, the pond is shallow and the light is strong, which is not conducive to the requirements of Pelteobagrus fulvidraco for low light feeding. Practice has proved that sandy soil is the best bottom material in ponds, and clay and hard ponds with low mud content can also be used. The bottom silt should not be too thick, about 10cm, which requires strong water and fertilizer conservation, fast decomposition of organic matter and easy fertilization of pool water.

2. Carrying capacity

The stocking density of Pelteobagrus fulvidraco in ponds is related to pond conditions, environmental factors, fish species specifications, feeding level, water sources and consumption habits. In the south of the Yangtze River, 2cm full-length fry are 8000- 10000 per mu, 3cm full-length fry are 6000-9000 per mu, and 4-5 cm full-length fry are 4000-6000 per mu. When the stocked Pelteobagrus fulvidraco grows to about 7-8 cm in length, the water quality has already become fat. At this time, about 200 silver carp and bighead carp are put into each mu. Its size is 2-3 inches, which is used to control the water quality of Pelteobagrus fulvidraco pond. The fry of that year can develop into commercial fish with the specification of 100- 150g. The yield per mu can reach 300-400 kg, or more than 800 kg (ideal pond conditions and bait).

Pond conditions, water sources and aerobic equipment are good, which can increase stocking by 50%- 100%.

3. Feed and feed

There are two kinds of feed for adult Pelteobagrus fulvidraco, pure animal feed and artificial compound feed, depending on the resources in various places.

(1) Pure animal feed: including small miscellaneous fish, shrimp, terrestrial earthworms, etc. These feeds are deeply loved by Pelteobagrus fulvidraco, but their sources vary from place to place, some places are rich in resources, and some places are limited in resources. Generally speaking, most farmers chop small fish and shrimp into fish paste and feed it directly. In some places, small miscellaneous fish and shrimp are chopped into pulp and mixed with plant powder feed to feed. First, mix dry powder feed for later use, and the standards are: fish meal 10%, soybean meal 30%, corn meal 10%, third-grade powder 25%, and mixture of vitamins and inorganic salts 1%. When feeding, powder feed is added to the fish slurry and can be used after being stirred into balls.

(2) Artificial compound feed: The nutritional requirements of the compound feed for Pelteobagrus fulvidraco commercial fish are: crude protein 38-40%, fat 7-9%, carbohydrate 20-23% and cellulose 5-6%. Animal raw materials of commercial fish feed for Pelteobagrus fulvidraco include fish meal, silkworm chrysalis, meat and bone meal, feather meal, blood meal, bacterial protein powder, yeast and so on. Plant raw materials include bean cake, cottonseed cake, corn and wheat flour. After the feed is crushed, it is processed into particles with the diameter of 1.5-2mm according to the formula, and then dried and stored. The formula of its adult fish feed is: fish meal 28%, feather meal 5%, meat and bone meal 5%, blood meal 8%, feed yeast 5%, soybean meal 14%, corn meal 3%, vegetable oil 2%, wheat flour 20%, vitamin mixture10% and inorganic salt additive 2%.

(3) Feeding: Feeding is the key technology in feeding. The so-called scientific feeding method is to adjust the feeding amount, feeding time and feeding types in time according to the different fish species and the changes of environmental factors, so as to meet the needs of fish for nutrients in a balanced way and give full play to the maximum utilization rate of feed. It is best to domesticate and feed in groups on the water like carp, grass and crucian carp.

4. Daily management of feeding

The daily management of the pond must be meticulous and lasting. The management scope mainly includes technical measures such as feed management, water quality management, daily management and fish disease prevention and control.

(2) Running water feeding

Pelteobagrus fulvidraco is a kind of fish suitable for intensive feeding. In recent years, in some places in China, other fish are mixed and fed by running water, and in a few places, the difference of reservoir water body and surplus hot water from factories are used for feeding, especially in small ponds, and other yields have reached 30-50 kilograms per cubic meter, which can be higher.

1, flow pool condition

According to the feeding characteristics and activity habits of Pelteobagrus fulvidraco, it is suitable for feeding in rectangular cement ground (the bottom of the pond must be hard mud or sand) and small ponds. Water keeps flowing in from one end and out from the other. Its specifications depend on its own conditions, and the size is appropriate. In general, it is best to control the flow rate of dissolved oxygen in the running water pool at 5 mg/L.

2. Fish stocking

Generally, the size of fish in the running pond is about 5cm, and 300-400 fish are stocked per cubic meter of water. When released, the fish should be strictly disinfected with 3% salt, and then put into the inflow pool.

3, bait and feeding

The key of running water feeding is to feed the complete compound bait, and the protein content of the compound bait is 40-48%. The feeding method is to set a certain number of bait tables on both sides of the running water pool, and there must be 10㎡ every 1.5㎡, and the bait tables should be set at the bottom of the pool about 5- 10 cm. The water supply varies according to the water temperature. When the general water temperature is 12- 18℃, the feeding amount accounts for 2.5% of the body weight. When the water temperature is 18-25℃, the feeding amount accounts for 3-3.5% of the total weight. When the water temperature is 25-30℃, the feeding amount accounts for 4-5% of the total weight, with more feeding times in the morning and evening, and less feeding times at noon and under strong light.

4. Feeding management

The water source for tap water cannot carry pollutants, the dissolved oxygen content is above 5 mg/L, and the pH value is 7.0-8.5. Feed should not be excessive, so as not to affect the water quality. Prevention and control of fish diseases must be carried out regularly. The carrying capacity of fish per cubic meter of water is generally maintained at about 30 kg.

(3) Intercropping in ponds

Pelteobagrus fulvidraco is mixed in the pond, and there are other kinds of fish in the pond. Usually, 2-3 cm long fry are directly interplanted in the pond to increase the yield and economic benefits of high-quality fish in the pond. There are two ways: one is to interplant about 300 fry with a length of more than 2 cm per mu in the pond with conventional feeding method, without feeding feed; Secondly, 500-600 Pelteobagrus fulvidraco are put into the pond to replace the carp and crucian carp in the conventional feeding method.

1, nesting conditions of fish ponds

The pond in which Pelteobagrus fulvidraco is interplanted in the pond must have pollution-free material water, and domestic sewage and other environments cannot be interplanted. The pond is equipped with escape prevention equipment, with pH value of 7-8.5 and dissolved oxygen of 4 mg/L. It is rich in natural bait resources (such as zooplankton, earthworms, small fish and shrimp, aquatic and terrestrial insects, etc.). ).

2. Planting density

The density of polyculture depends on the bait. General commercial fish ponds are fed with artificial bait, with 300 fish per mu and a yield of 30-40 kg. In carp-free crucian carp ponds, 500-600 carp are interplanted per mu, and the output is 60-80 kg. The specifications of interplanted fry are generally more than 2 cm.

3. Setup management

In the interplanting management of Pelteobagrus fulvidraco, the dissolved oxygen in the feeding water should be kept above 4 mg/L, and the escape prevention in the pond should be done well to prevent Pelteobagrus fulvidraco from escaping. Attention should be paid to using drugs to prevent other fish diseases from affecting the normal growth and death of Pelteobagrus fulvidraco. When the yellow croaker does not grow to about 100g, it is best not to hook the fish, because it is easier for yellow croaker to take the bait when swimming.

Fourth, disease control.

In the feeding process, the disease prevention of Pelteobagrus fulvidraco is more important. While increasing the yield per unit area, increasing the stocking density and expanding the feeding area, a series of epidemics may occur. The harm of fish diseases has been found in the cultivation of fry and adult fish. Therefore, strengthening disease prevention is an important management measure to improve survival rate and yield.

(A) the cause of the disease

1, the fish pond is not disinfected, or the disinfection treatment is not strict, or the disinfection drug fails.

2. The stocking density of fry is too high, and the water quality becomes worse, which reduces the disease resistance of fish.

3. Live baits such as Daphnia and earthworm are brought into pathogens without disinfection; Or because these baits are rich in heavy metal ions, fish get sick after eating a lot of live baits; Fish diseases may be caused by feed deterioration, uneven feeding or improper fertilization.

4. The fish is in poor health, or injured during transportation, invaded by pathogens, or the fry itself is sick.

5. Seeds and tools were not disinfected, and pathogens were brought in.

6, the water source is not good, or the dead fish cross repeatedly infected.

(2) Preventive measures

1. Thoroughly clean the fish pond and strictly clean and disinfect the pond.

2. When the fry are stocked, they should be disinfected with nitrofurazone solution and 2-3% salt solution.

3. Stocking disease-free seedlings with strong physique and large specifications.

4. It is best not to feed live baits such as Daphnia and Eisenia foetida from urban sewage culverts and drainage ditches, but to cultivate live baits artificially.

5. Do not feed the spoiled feed, and implement the feeding rules of "four determinations" and "four observations". The fertilizer must be fully fermented and decomposed before entering the pool.

6. Investigate and summarize the types and incidence of fish diseases in this area, and take effective preventive measures. Sprinkle with quicklime, trichlorfon, strong chlorine essence and copper sulfate. Disinfect live bait, eating table and eating ground regularly. One of the most effective measures to prevent diseases in cage culture of Pelteobagrus fulvidraco is to set the cage in open water with certain wind waves or running water, and the cage density should not be too high. It is best to move the cage often in dry season.

(3) Tolerance of Pelteobagrus fulvidraco fry to several commonly used drugs

The 24-hour lethal concentration of Pelteobagrus fulvidraco to commonly used aquatic drugs is: copper sulfate 0.69 mg/L: 90%% crystal trichlorfon 2.8 mg/L; 2.5% salt; Malachite green 0.1.5mg/l; Formalin 68 mg/L; Aminamine -T 8.4mg/L: The tolerance of Pelteobagrus fulvidraco to common aquatic drugs is not as good as that of the four major fishes, which may be due to the fact that Pelteobagrus fulvidraco is a scaleless fish and the drugs are easily immersed in the body from the skin. Therefore, the dosage of Pelteobagrus fulvidraco must be strictly controlled to prevent death from acute and chronic poisoning. Sensitive to malachite green, copper sulfate, mercurous nitrate, potassium permanganate, trichlorfon, etc., use with caution.

(D) prevention and treatment of several common frequently-occurring diseases

1, hemorrhagic edema disease

(1). Pathogen: According to preliminary research, the pathogen system is bacteria.

(2) Symptoms: the body surface of the diseased fish turns yellow and mucus increases; Pharyngeal skin is damaged and congested, with round holes; Abdominal swelling, anal swelling, eversion; The head is congested, the dorsal fin is swollen, the base of pectoral fin and ventral fin is congested, the fins are ulcerated, and even the abdomen is longitudinally split from pectoral fin to ventral fin, and bile extravasates. There is a lot of blood or yellow glue in the abdominal cavity, no food in the gastrointestinal tract, pale stomach, yellow glue in the intestine, yellow liver, necrosis of the spleen and moldy black spots on the kidney.

(3) Harm and epidemic The disease is the most harmful in the breeding period of fry and adult fish. Sometimes, some sick fish can be seen spinning around in the water and die soon. Especially in the process of seedling raising, the mortality rate is as high as 80%. The outbreak of high temperature season is fierce and spreads rapidly. When the water temperature is 25-30℃, a large number of sick fish will obviously die.

(4) Prevention and control methods

(1) Pay close attention to the water quality, maintain good pond environmental conditions, keep the dissolved oxygen in the pond above 5mg/L, and halve the pond water body.

② Reduce the stocking density of fry appropriately.

③ 0.25-0.3g/m strong chlorine essence? Disinfect the water once a day for three days.

④ Add 0.6—0.7g tetracycline per kg of dry feed, 1 time, 3 days a day.

⑤ When feeding fish pulp, add 1% salt to the feed every day.

2, enteritis

(1) pathogen: Aeromonas punctata.

(2) Symptoms: the sick fish has swollen abdomen, red and swollen anus and mild abdominal pressure. Yellow mucus flowed out of the anus, and the sick fish swam alone. When the belly of the fish is cut open, the esophagus and foregut are congested and inflamed, and the inflammation of the whole intestine is reddish in severe cases, and the blood is thicker than the whole intestine, so both species and adults can occur.

(3) Harm and epidemic: enteritis mainly harms fish species and salted fish. This disease may be directly transmitted by fish, so it can also be transmitted by mixing sick fish with healthy fish. Because bacteria can survive in pond sludge, infection may also come from sludge. In addition, zooplankton and earthworms eaten by fish, as well as fish slurry in artificial feed, may also carry pathogens.

(4) Prevention and control methods:

① The pond should be thoroughly cleaned and disinfected, and the fish should be bathed and disinfected with 2 ~ 3% salt solution before entering the pond.

(2) Don't feed moldy and rotten feed, disinfect the moving animals with 2 ~ 3% salt solution, and add 1% salt to the mixed feed regularly; Or add 0. 1% fresh garlic juice.

③ Spraying 1ppm bleaching powder in the whole pond and feeding sulfaguanidine bait. For every 100kg of fish, the dosage is 10g on the first day and halved on the second day. Continuous use for 6 days is a course of treatment; Or 0.3-0.4g of furazolidone is mixed into each kilogram of feed for 2-3 days continuously; Or add 40- 100 g oxytetracycline feed powder per 100kg feed for 5-7 days continuously.

3. Hydromycetes

(1) pathogen: water mold.

(2) Symptoms: When the water mold parasitized for the first time, it was invisible to the naked eye. When visible to the naked eye, the mycelium has invaded the wound and grown inward and outward. Spread, spread, like gray cotton wool. The sick fish swam abnormally and fidgeted until their muscles rotted, they lost their appetite and died of emaciation: the fish eggs were covered with hyphae and turned into white fluffy balls, and the moldy fish eggs turned into dead fish eggs.

(3) Endangering and spreading the hatched eggs, injured fry and adult fish that seriously endanger the surface of fish. This disease is most likely to occur in early spring and winter.

(4) Prevention and control methods

① Cleaning the pond with quicklime and disinfection can reduce the occurrence of this disease.

(2) In the process of fishing, transportation and stocking, try to avoid hurting fish. And master the reasonable stocking density.

③ Apply 1% malachite green ointment or an appropriate amount of iodonium ointment to the injured fish.

④ Soak sick fish with malachite green, 4-5 mg/L for big fish and 2 mg/L for small fish, and pay attention to the soaking time.

⑤ When hatching fish eggs, it can be disinfected with 7 mg/L malachite green for 8- 10 minutes for 2 days, and then on the water surface near the fish egg incubator every morning and evening 1 time, the dosage is to make the pool water light green until the fry hatch. When unbonded flowing water hatches, malachite 1 time reaches 0.5 mg/L every 6-8 hours, which can effectively inhibit the infection of water mold.

4. Cucumber disease

(1) pathogenic root-knot nematode

(2) The symptoms are on the skin, fins and gills of the diseased fish, and small white cysts can be seen with naked eyes. In severe cases, the body surface seems to be covered with a white film. Sick fish react slowly or float on the water. Due to bacterial infection at the focus, the surface of the fish is inflamed, or local necrosis, scale shedding, fin crack, gill epithelial hyperplasia and gill small piece destruction occur. If a worm invades the cornea, it will become inflamed and become blind. Eventually he died of dyskinesia and dyspnea. Pelteobagrus fulvidraco is prone to melon diseases and often leads to explosive death. The suitable breeding water temperature of summer squash is 15-25℃, and the pH value is 6.5-8.0, which is rare in summer. In the case that melons are cultivated too densely, the bait is lacking and the fish is thin, it is particularly easy to be infected by melons.

(3) Prevention and control methods

① Production measures, such as cleaning the quicklime pond, disinfection of fish and reasonable stocking, can prevent the spread of cucurbitaceae.

② Soak the sick fish in 60-80 mg/L formalin for 65,438+00-65,438+08 minutes (depending on the water temperature), soak them again for 65,438+0 times the next day, and then transfer them to the pond for breeding. The original pool was thoroughly disinfected with formalin. This method is only effective in the early stage of the disease. If it is found late, the diseased fish will be covered with white spots, and even if it is used continuously, the fry will lose a lot. It should be pointed out that Pelteobagrus fulvidraco is very sensitive to mercurous nitrate, so the dosage must be accurate. The waiting time for soaking sick fish should also be strictly controlled, otherwise it will easily cause phytotoxicity.

5, flagellate disease and rotavirus disease

(1) The pathogens of carp, trypanosoma and rotifer, are common complications.

(2) The L gill and skin of symptomatic fish are parasitized by a large number of worms, which often make the fry of Pelteobagrus fulvidraco sick, and sometimes adult fish and parent fish are infected. Oblique tube worms like to parasitize in the edges or gaps of Pelteobagrus fulvidraco, and also attack the skin on the body surface, stimulating the host to secrete a lot of mucus, forming a yellowish or bluish viscous liquid layer on the body surface, making sick fish wander. Head down, tail up, lying on the surface of the water or lying sideways under the water, breathing difficulties, and soon died. Rotifers parasitic on the body surface are larger, while rotifers parasitic on gills are generally smaller. When seriously infected, the sick fish swim wildly along the pond, showing the phenomenon of "horse racing", and sometimes a layer of white line appears on the body surface: ring rot is most likely to occur in the case of small area, shallow water, poor water quality, high stocking density, insufficient feed, continuous drizzle and water temperature 18-28℃.

(3) Prevention and control methods

① Thoroughly clean and disinfect the pond with quicklime.

② Soak the fish with 1-2 mg/L copper sulfate solution, and pay attention to the soaking time according to the water temperature.

③ Spraying 0.4 ~ 0.5 mg/L mixture of copper sulfate and ferrous sulfate all over the body has a good effect.

In addition, Pelteobagrus fulvidraco belongs to the bottom fish, and the residue, bait and fish manure are easy to accumulate at the bottom of the pond, causing the increase of fish skin mucus, leading to fish diseases, affecting fish breathing and thus dying. At the peak of feeding, it is necessary to spray or drain the bottom water of the whole pond with quicklime slurry every half month, and inject new water to improve the bottom material and water quality.

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