Efficient breeding of Astragalus membranaceus with bait
Huang Wei, also known as Huang Lading and Gayu, is a small freshwater economic fish. It is omnivorous, has strong adaptability, does not require high water quality, and is easy to introduce and domesticate. Because of its high nutritional value, it is increasingly favored by consumers, and it is also an excellent variety suitable for eating and fishing to improve the structure of cultured varieties. In recent years, we have continuously carried out the main culture experiments in small ponds, and all of them have achieved good results. Now, the key link bait technology for efficient culture of Astragalus membranaceus in small ponds is introduced as follows:
1, bait preparation
The food in natural waters is mainly shrimp, fish and fish eggs and some aquatic insects. Aquatic plants, etc., so fresh animal bait can be used for artificial breeding. In recent years, we have adopted self-made compound bait for domestication and feeding. The bait is made of imported fish meal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worms and other feed additives, with an early protein content of more than 34% and a fat content of 4%. In the later stage, some imported fish meal can be replaced by small miscellaneous fish meal, with protein content of 30% and fat of 6%. Feeding bait must be fresh and free from mildew and rancidity.
2. Domestication
Wild Astragalus membranaceus likes to eat in the daytime and at night. After 5-7 days domestication under artificial breeding conditions, it can completely feed on the bait table during the day. After two days in the pond, the seedlings were domesticated by artificial feeding, with fixed feeding signals during domestication, and fixed-point and regular feeding training was carried out. After patient domestication for 5-7 days, the feed can be fed normally; The domesticated fry released in this way can be fed normally the next day after entering the pond, and the feeding method can adopt two forms: 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 3 times a day in July, August and September, and the feeding rate is 2%-3%; After the third stage 10, the bait was fed twice a day, and the feeding rate was 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, the fish on the bait should stop eating after 90% leaves the table; In the second stage, because the weather is hot and the water quality is easy to fluctuate, 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 the bait should be increased accordingly, and the particle size of the adult fish feed can reach more than 5 mm with the particle size of 2.0 mm as the opening feed. It is required that the particles should have the stability of 15 minutes in water when using sinking hard particle bait; Using floating bait will better improve the utilization rate of bait.
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Intensive culture technology of Pelteobagrus fulvidraco in pond
Pseudobagrus fulvidraco is a catfish order. Family, Pelteobagrus. Some places are also called Huang Lading, Huang Yagu, Yellow-fin Fish, Silurus japonicus and so on. Its body color is gorgeous, its meat is tender and delicious, its nutrition is rich, its edible rate is high, its vitality is strong, and its temperature range is wide, so it is a new breed that can be developed. The biological characteristics and intensive culture techniques in ponds are introduced as follows:
I. Biological characteristics
1.Morphological characteristics: long body length, wide and flat head, bulging back, flat abdomen, slightly flat rear part of body, thick and short tail handle, big mouth crack, shorter jaw than upper jaw, with fine teeth and 4 pairs of whiskers, small lateral eyes, hard spines on dorsal fin and pectoral fin, serrated upper pectoral fin, slightly fan-shaped, near ventral fin at the end, 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 reach16 ~ 20 cm, and the largest individual can reach more than 500g g. Generally, the second-year-old fish is mature, and the sexual mature individuals is generally male than female. The spawning period is 5 ~ 7 months, which is a multi-year spawning type. In the reproductive period, the male fish has nesting, egg protection and larvae. The suitable breeding water temperature is 23 ~ 30℃, and the number of eggs per tail is 2000 ~ 3600, which usually lays eggs at night. The fertilized egg is slightly yellow and sticky, with an egg diameter of about 2 mm. The water temperature is 23 ~ 28℃, and the seedlings can emerge after 50 ~ 60 hours of incubation.
Second, pond culture technology
1.Pond preparation: Generally, the size of 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 inlet (the slope should not be too large), and a fish-collecting pit of 50 ~ 60m2 with a depth of 20 ~ 40cm should be dug for dry pond fishing; It is required that the pond has sufficient water, fresh water quality, convenient water intake and drainage, and the water depth can be kept at1.5 ~ 2m. The planned output is above 1 50kg/667m2, and12kw aerator shall be equipped; Eliminate excessive silt and keep about 10cm; Clean the pond with 150kg quicklime dry method every 667m2 water surface, mix the bottom mud with lime as well as possible, and inject water 80cm； per week after exposure/kloc-0; After applying fermented organic fertilizer100 ~ 200 kg every 667m2, when a large number of plankton are cultivated, fish can be released.
2. Fish stocking: The stocking time is generally from March to April, and the stocking density can be flexibly mastered according to the pond conditions, management level, feed and expected specifications. The fingerlings should be stocked by individuals with neat specifications, bright colors, smooth surface and strong physique. Generally, 2,000 ~ 4,000 Astragalus membranaceus seedlings with a length of 5cm are stocked in 667m2, and if the fingerlings are about 30g, they are stocked every 667m21500 ~ 3,000. Soak10 ~15 minutes with 5% salt solution before stocking, and try to avoid using drugs with strong oxidation such as potassium permanganate. After stocking Pelteobagrus fulvidraco15 ~ 20 days, 200 ~ 400 silver carp with body length10 ~15 cm were reared on every 667m2 water surface.
3. Feed feeding: under the condition of artificial feeding, small fish and shrimp and animal leftovers can be fed, and fish meal, meat and bone meal, blood meal, soybean meal and feed additives can also be made into pellets 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, and promote growth and reduce feed coefficient. However, it should be noted that it cannot be used with colistin sulfate and furazolidone. 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 seedlings, they can be fed normally on the second day after entering the pond. After eating normally, the feeding rate is1%~ 3% before April, and it is 4% ~ 6% in the peak season. Feed 1 time every morning and afternoon. Feed feeding should be "four fixed".
4. Daily management: In the process of Pelteobagrus fulvidraco culture, water quality management is the key, with water injection 1 time per month from May to June, with a depth of 30cm, and water injection 1 time per half month from June to September, with a depth of 20cm. Sprinkle15g/m3 quicklime once a month in hot season, and start the aerator at the right time. Usually pay attention to patrol the pond, observe, fish weeds and dirt, and keep records. Pelteobagrus fulvidraco is a scaleless fish with low tolerance to commonly used drugs, so high-efficiency and low-toxicity drugs should be used as far as possible to prevent and treat fish diseases. This species is sensitive to malachite green, copper sulfate, trichlorfon, potassium permanganate and other drugs, so it should be used with caution.
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Biology and artificial culture technology of Pelteobagrus fulvidraco (yellow larding)
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 per100g contains protein 16. 1g, fat 2. 1g, carbohydrate 2.3g, calcium 154mg, and phosphorus 504mg．, which contains various essential substances in human body. According to medical history books, Pelteobagrus fulvidraco has anti-inflammatory and analgesic effects.
Second, biological characteristics of Pelteobagrus fulvidraco
(A) classification is status
Pelteobagrus fulvdrace (Richardson) is a fresh water economic fish widely distributed in fresh water bodies in China, commonly known as Gayazi, Yellow Labing, Yellow Finfish, etc., and its English name is Yellow catfish, which belongs to Silurus, Lepidoptera and Pelteobagrus in fish classification. There are 4 species in this genus: Pelteobagrus fulvidraco, Pelteobagrus fulvidraco (Pelteobagrus vachelli), Pelteobagrus fulvidraco and Pelteobagrus fulvidraco. At present, the main breeding target 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 belongs to benthic fish. Baitianxi lives in the bottom of the water body and swims to the top of the water body for food at night, so it has strong adaptability to ecological environment conditions. According to relevant data, the average oxygen consumption rate is 0. 14 1mg/ hour and the ventricular resting point is 0.3 14mg/L at the water temperature of 28-29℃, so it has strong adaptability in the hypoxic environment. In winter, the temperature is low, even after leaving the water body for several hours (as long as a certain humidity is maintained). Can still survive. Sometimes in late autumn and early winter, when people transport Pelteobagrus fulvidraco to the market for short distance, they use a layer of aquatic plants at the bottom of the bamboo basket, then put Pelteobagrus fulvidraco on it, and then put aquatic plants to keep it moist for transportation. After a few hours, all the inflated fish put into the temporary culture pond on the market can survive. Pelteobagrus fulvidraco often lives in the environment with slow river flow and rocky or pebble, 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 the wintering place and eat in the nearby rocky shoals and near rocks. During the day, they mainly lived among the rocky or pebbles with deep water, and swam to the rocky areas in shallow water at night to prey. At dawn, they often saw Pelteobagrus fulvidraco rushing to find caves and crevices. When the water in rivers, lakes and reservoirs rises in summer, the water becomes turbid. During this period, Pelteobagrus fulvidraco mostly swims to the wide chamfer to feed on mosquito larvae brought or grown by the water body, and gradually swims to rocky rivers and deep caves of lakes with deep water to feed in autumn and winter with the changes of the clear water body of rivers and lakes and the drop of water temperature. Pelteobagrus fulvidraco likes to congregate and feed and move in low light.
(3) Feeding habits
Pelteobagrus fulvidraco is an omnivorous fish, and the feeding habits of Pelteobagrus fulvidraco are significantly different with different individual sizes. From the 4th to 5th day after hatching, it began to eat zooplankton, such as rotifers, copepods and cladocera, and artificially fed with feed such as egg yolk. The body length is 5-8 cm, and the main foods are cladocera, copepods, chironomid larvae, earthworm and artificial mixed feed (fish paste and plant feed mixture). The main foods above body length 10cm are: snails, shrimps, small fish, chironomid larvae, ephemera larvae, COLEOPTERA larvae, insect eggs, green water spiders, sowthistle leaves, POTAMOGETON malayi leaves, plant fibrous roots and detritus, fish scales, silt and other fish that are produced on aquatic plants and stones. Under the condition of artificial feeding in ponds, in addition to feeding the natural bait organisms in ponds, it is generally necessary to feed artificially prepared soft compound bait, hard pellet feed and floating feed, especially under the condition of intensive cage running water feeding, the protein content of the compound bait must reach 35-40%.
Third, adult fish breeding
The commercial fish breeding of Pelteobagrus fulvidraco is called adult fish breeding, which refers to the production process of raising commercial fish with fish species over 2cm. 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 those in this field) have begun to actively carry out the research on the main culture and mixed culture of Pelteobagrus fulvidraco in artificial ponds, and have obtained a series of mature technical data, especially in the large-scale artificial propagation of fry, thus alleviating the contradiction of tight supply of fry. The experimental research shows that Astragalus membranaceus is suitable for raising in ponds, cages, large and small lakes, rice fields and other water bodies, which can be mainly raised and mixed with silver carp, bighead carp, bream and grass carp. But it is not suitable to be mixed 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 raised in ponds.
Pond farming is a new farming method that emerged in recent two years. Pond farming has the characteristics of small investment, no limitation of 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 of fishery water, and does not contain substances harmful to fish. It is best to choose fish ponds close to reservoirs, lakes, rivers and ditches, or fish ponds equipped with mechanical equipment such as aerators and pumps for main culture of Pelteobagrus fulvidraco. The main culture density of the pond is high, and the water quality is easy to deteriorate because of 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 ponds, 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 bottom material of Pelteobagrus fulvidraco are not strict with adult fish breeding ponds, and both large and small fish ponds can be used to cultivate adult fish. It is best to choose a pond whose bottom at the outlet of the pond is 10%-20% deeper than other places, which is mainly convenient for commercial fish to catch in the dry pond and each pond must have controllable inlet and outlet. Generally, the main pond area is 3-5 mu or less than 10 mu. The water depth of1.5-2.0m is ideal, and the pond is shallow and the illumination is strong, which is not conducive to the requirement of Pelteobagrus fulvidraco feeding in weak light. Practice has proved that sandy soil is the best bottom material in ponds, and clay and hard ponds with little mud are also acceptable. The mud at the bottom should not be too thick, about 10cm, and it is required to have strong water and fertility conservation, fast decomposition of organic substances and easy fertilization of pond water.
2. Stocking density
The stocking density of the main cultured yellow catfish in the pond is related to the conditions of the fish pond, environmental factors, fish species specifications, feeding level, water source and consumption habits. In the south of the Yangtze River, the full-length fry of 2cm per mu are 8000-10000, the full-length fry of 3cm are 6000-9000 per mu, and the full-length fry of 4-5 cm are 4000-6000 per mu. When the stocked Pelteobagrus fulvidraco grows to a body length of about 7-8 cm, the water quality has begun to become fat. At this time, about 200 silver carp and bighead carp are put into each mu. Its size is 2-3 inches to control the water quality in Pelteobagrus fulvidraco pond. The fry of that year can develop commercial fish with the specification of100-150g. The yield per mu can reach 300-400 kg, or more than 800kg (ideal pond conditions and bait).
If the pond conditions, water sources and aerobic equipment are good, the stocking amount can be increased by 50%- 100%.
3. Feed and feeding
There are two kinds of feed for adult Pelteobagrus fulvidraco, pure animal feed and artificial compound feed, depending on the resource situation in various places.
(1) Pure animal feed: including small miscellaneous fish, shrimp, terrestrial earthworms, etc. These feeds are popular with Pelteobagrus fulvidraco, but their sources are different from place to place, some places are rich in resources, while others are limited. In general, most breeders mince small fish and shrimp into fish slurry and feed it directly. In some places, small miscellaneous fish and shrimp are minced into slurry and mixed with plant powder feed and fed. The method comprises the following steps: firstly, mixing dry powder feed for later use, and the standard is: fish meal 10%, soybean meal 30%, corn meal 10%, third-class flour 25%, and the mixture of vitamins and inorganic salts each accounts for 1%. When feeding, powder feed is added to the fish slurry, and it can be used after being stirred into a ball.
(2) Artificial compound feed: The nutritional requirements of the compound feed for Pelteobagrus fulvidraco commercial fish are as follows: crude protein is 38-40%, fat is 7-9%, carbohydrate is 20-23%, and cellulose is 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, etc., and plant raw materials include soybean cake, cottonseed cake, corn and wheat flour, etc. After the feed is crushed, it is processed into granules with the diameter of1.5-2mm according to the formula, and then it is dried for reserve. Its adult fish feed formula: 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 mixture 1% 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 adopt domestication to feed in groups on the water surface like carp, grass and crucian carp.
4. Daily management of feeding
The daily management of ponds must be meticulous and lasting. The management scope mainly includes technical measures such as feeding feed management, water quality management, daily management and fish disease prevention and control.
(2) Feeding with running water
Pelteobagrus fulvidraco is a kind of fish suitable for intensive feeding. In recent years, in some places in our country, mixed culture is carried out among other fish for running water feeding, and in a few places, the difference of reservoir water body and residual hot water from factories are used for feeding, especially in small ponds, and other yields have reached 30-50kg per cubic meter, which can be higher.
1, flow pool conditions
According to the feeding characteristics and activity habits of Pelteobagrus fulvidraco, it is suitable for feeding in rectangular cement (the bottom of the pond must be hard mud or sandy) and small ponds. Water flows in from one end continuously and flows out from the other end. Its specifications depend on its own conditions, and its size can be suitable. Generally, it is best to keep the flow rate of dissolved oxygen in the running water pool at 5 mg/L.
2. Fish stocking
Generally, the fish species in the running pool are about 5cm in size, and 300-400 fish are stocked per cubic meter of water. When releasing, the fish should be strictly disinfected with 3% salt, and then the fish should be put into the inflow pool.
3, bait and feeding
The key of running water feeding is to feed the complete compound bait, the protein content of which is 40-48%. The feeding method is to set a certain number of bait tables on both sides of the running water pool, and every 10㎡ must have 1.5㎡, and the bait tables should be set at the bottom of the pool about 5-10 cm. The feeding amount varies according to the water temperature. Generally, when the water temperature is12-18℃, the feeding amount accounts for 2.5% of the body weight. When the water temperature is18-25℃, 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, and the feeding times are more in the morning and evening, and less at noon and when the light is strong.
4. Feeding management
The water source used for running water can't carry pollutants, the dissolved oxygen content is above 5 mg/L, and the pH value is 7.0-8.5. The 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 around 30kg.
(3) Pond intercropping
Pelteobagrus fulvidraco is polycultured in ponds where other species are raised. Usually, 2-3 cm long fry are directly interplanted in ponds to increase the yield of high-quality fish and economic benefits in ponds. There are two ways: one is to interplant about 300 fry with a length of more than 2cm per mu in the pond with conventional feeding methods, without feeding feed; Secondly, 500-600 Pelteobagrus fulvidraco were put in the pond instead of carp and crucian carp in the conventional feeding method.
1, fish pond conditions
The pond in which Pelteobagrus fulvidraco is interplanted in the pond must have pollution-free substance water, and the environment such as domestic sewage 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, and is rich in natural bait resources (such as zooplankton, earthworm, small fish and shrimp, aquatic and terrestrial insects, etc.).
2. Planting density
The density of polyculture should be determined according to the bait situation. Generally, the pond fed with artificial bait in commercial fish ponds has 300 fish per mu, and its output is 30-40kg. In ponds without carp and crucian carp, 500-600 fish per mu are interplanted, and its output is 60-80kg, and the specifications of the fry for interplanting are generally required to be more than 2cm long.
3. Set-up 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 fleeing. Attention should be paid to the drugs used to prevent other fish diseases from affecting the normal growth and death of Pelteobagrus fulvidraco. When the yellow-bearded fish does not grow to the weight of 100g, it is best not to hook the fish, because it is easier for Pelteobagrus fulvidraco to be hooked when swimming.
Fourth, disease control
In the feeding process, the disease prevention and control of Pelteobagrus fulvidraco is more important. While increasing the yield per unit area and increasing the stocking density to expand the feeding area, a series of epidemic diseases may occur. The harm of fish diseases has been found in the breeding of fry and adult fish. Therefore, strengthening disease prevention is an important management measure to improve the 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. The live baits such as Daphnia and Eisenia lumbricoides were not disinfected and brought in pathogens; Or because these baits are rich in heavy metal ions, fish eat a lot of these live baits and get sick; Fish diseases may be caused by spoilage of feed, uneven feeding or improper fertilization.
4. The fish's physique is poor, or it is injured during transportation, pathogen invades, or the fry itself is sick.
5. The seeds and tools were not disinfected and brought in pathogens.
6, poor water sources, or cross-repeated infection of dead fish.
(2) Preventive measures
1, thoroughly clean the fish pond and strictly clean the pond for disinfection.
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 bait such as Daphnia and Eisenia from urban sewage culvert and drainage ditch, and adopt the method of artificially cultivating live bait.
5. Do not feed spoiled feed, and implement the feeding rules of "four decisions" and "four observations", and the fertilizer will not go into the pond until it is fully fermented and decomposed.
6. Investigate and summarize the types and incidence of fish diseases in this area, and take effective preventive measures. Sprinkle quicklime, trichlorfon, strong chlorine essence, copper sulfate, etc. on a regular basis, and disinfect live bait, eating table and eating ground. One of the most effective measures to prevent disease in cage culture of Pelteobagrus fulvidraco is to set the cage in an open water area with certain wind and waves or running water, and the density of the cage should not be too high. It is best to move the cage frequently 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; Salt 2.5%; Malachite green 0.15 mg/l; Formalin 68mg/l; Aminamine -T 8.4mg/L: The tolerance of Pelteobagrus fulvidraco to common water 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 caused by acute and chronic poisoning. It is sensitive to malachite green, copper sulfate, mercurous nitrate, potassium permanganate and trichlorfon, so it should be used with caution.
(D) Several common and frequently-occurring disease prevention and treatment methods
1, hemorrhagic edema disease
(1), pathogen: According to the preliminary study, the pathogen system is bacterial.
(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 and 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 cracked from pectoral fin to ventral fin, and bile is extravasated. There is a lot of blood or yellow jelly in the abdominal cavity, there is no food in the stomach and intestine, the stomach is pale, the intestine is full of yellow glue, the liver is yellowish, the spleen is necrotic, and there are mildew black spots on the kidney.
(3) Harm and epidemic The disease is the most harmful during the breeding period of fry and adult fish, and sometimes it can be seen that some sick fish keep spinning in the water and die soon. Especially in the process of seedling cultivation, the mortality rate is as high as 80%. Outbreaks in high temperature season, with fierce force and rapid spread. When the water temperature is 25-30℃, a large number of sick fish will die obviously.
(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 change the pond water body to half.
② Reduce the stocking density of fry appropriately.
③ 0.25-0.3g/m of strong chlorine essence? Disinfect water once a day for three consecutive days.
④ Add 0.6—0.7g tetracycline to the feed per kg dry feed, once a day 1 time for 3 days.
⑤ When feeding fish pulp, add 1% salt to the feed every day.
2, enteritis
(1) Pathogen: Aeromonas punctata.
(2) Symptoms: The sick fish's abdomen is swollen, the anus is red and swollen, and the abdomen is lightly pressed. There is yellow mucus flowing out of the anus, and the sick fish swims alone. When the belly of the fish is cut open, the esophagus and foregut are congested and inflamed in patients with mild illness, and the inflammation of the whole intestine is light red in severe cases, and the blood is thick enough to fill the intestine, and both species and adults may occur.
(3) Harm and epidemic: Enteritis mainly harms fish species and salted fish. This disease may be directly transmitted by fish, so the disease can 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 the fish, as well as fish slurry in artificial compound feed, may also carry the pathogen.
(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 going into the pond.
(2) Don't feed moldy and rotten feed, disinfect active 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, feeding sulfaguanidine bait, and taking 10g on the first day for every 100kg of fish, and halving it the next day. Continuous use for 6 days as a course of treatment; Or 0.3-0.4g of furazolidone is mixed in each kg of feed for 2-3 days; Or add 40-100g of oxytetracycline feed powder to every100g of feed for 5-7 days continuously.
3. Water mold
(1) pathogen: water mold.
(2) Symptoms: When the water mold is parasitized for the first time, it can't be seen by naked eyes. When it can be seen by naked eyes, the mycelium has invaded the wound and grown inward and outward. Spread and spread, like gray cotton wool. Sick fish swim abnormally and are restless until their muscles rot, they lose their appetite, and they die of emaciation: the fish eggs are covered with hyphae and turn into white velvet balls, and the moldy eggs become dead fish eggs.
(3) Harm and epidemic seriously harm the hatching fish eggs and the wounded fry and adult fish on the fish body surface. 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 fish injury. And master the reasonable stocking density.
③ Apply 1% malachite green ointment or an appropriate amount of iodoamine ointment to the injured fish.
④ Soak sick fish with malachite green, big fish with 4-5 mg/L and small fish with 2 mg/L. Pay attention to the time of soaking.
⑤ For hatching fish eggs, 7 mg/L malachite green can be used for soaking and disinfection for 8-1 0 minutes, for 2 consecutive days, and then1time can be sprinkled on the water surface near the fish egg incubation rack every morning and evening, and the dosage is to make the pool water light green until the fry hatch. When unbonded flowing water hatches, malachite 1 time is added every 6-8 hours to reach 0.5 mg/L, which can effectively inhibit the infection of water mold.
4, small melon disease
(1) Pathogen Polygamous Meloidogyne
(2) The symptoms are on the skin, fins and gills of the diseased fish, and small white punctate cysts can be seen with naked eyes. In severe cases, the body surface seems to be covered with a white film. Sick fish are slow to respond or float on the water. Due to the infection of bacteria at the focus, the fish surface is inflamed, or there is local necrosis, scale shedding, fin cracking, gill epithelial hyperplasia and gill small piece destruction. If the worm invades the cornea, it can become inflamed and blind. Eventually he died of dyskinesia and dyspnea. Pelteobagrus fulvidraco is susceptible to cucurbit disease, and often leads to fulminant death. The suitable breeding temperature of Cucurbita maxima is15-25℃, and the pH value is 6.5-8.0, which is rare in summer. It is especially easy to be infected by cucurbits when they are over-densely cultivated, lack of bait and thin fish.
(3) Prevention and control methods
① Production measures such as quicklime pond cleaning, fish disinfection and reasonable stocking can prevent the spread of cucurbitaceae.
(2) Soak the sick fish 1 0-18 minutes with formalin 60-80 mg/L (depending on the water temperature), then soak1time every other day, and then transfer to the pond for feeding. 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 small white spots, and even if it is used continuously, the loss of fry will be great. It should be pointed out that Pelteobagrus fulvidraco is very sensitive to mercurous nitrate, so the dosage must be accurate. The waiting time of soaking sick fish should also be strictly controlled, otherwise it will easily cause phytotoxicity.
5, trichuriasis and wheel disease
(1) Pathogens of Cyprinus carpio, 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 causes the disease in the fry of Pelteobagrus fulvidraco, and sometimes the 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 pale or light blue sticky and liquid layer on the surface, and making sick fish stray. Head down, tail up, lying on the surface of the water or lying on your side underwater, breathing difficulties, and soon died. The rotifers parasitic on the body surface are larger, while the rotifers parasitic on the gills are generally smaller. When seriously infected, the sick fish swim wildly along the pond, showing the phenomenon of "horse racing", and sometimes there is a layer of white line on the body surface: wheel disease is most likely to occur in the case of small area, shallow water, poor water quality, high stocking density, insufficient feed, continuous continuous rain and water temperature18-28℃.
(3) Prevention and control methods
① Thoroughly clean and disinfect the pond with quicklime.
② Soak fish with1-2 mg/L copper sulfate solution, and pay attention to the soaking time according to the water temperature.
③ The mixture of 0.4 ~ 0.5 mg/L copper sulfate and ferrous sulfate was sprayed all over, and the curative effect was good.
In addition, Pelteobagrus fulvidraco belongs to the bottom fish, and the residue, bait and fish feces are easy to accumulate at the bottom of the pond, causing the increase of fish skin mucus, leading to fish diseases and affecting fish breathing, thus dying. In the peak period of breeding and feeding, it is also necessary to spray or drain the bottom water with quicklime slurry in the whole pool every half month, and inject new water to improve the bottom material and water quality.
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