Eel alias: white eel, white eel, river eel, eel, green eel, wind man, Japanese eel. Eel refers to the general name of species belonging to eel classification. Below, I will provide you with eel farming technology, hoping to help you!

Disease control and eel disease control

Eel culture should pay special attention to the prevention and treatment of fish diseases. The main diseases are water mold, melon diseases, ring rot, anchor head disease, gill rot, eel nematode disease and red fin disease, which can be controlled by conventional methods.

Etiological symptoms, prevention and treatment of branchial diseases

During the high temperature period in summer, eels eat too much, the sewage can't be discharged, and the organic sundries in the pond rot and deteriorate; Heavy rain causes changes in water sources; Frequent use of highly irritating pesticides is a latent factor leading to gill diseases of eel, while parasites lead to gill filament gaps, which easily lead to the breeding of pathogenic microorganisms and eventually lead to the outbreak of gill diseases of eel.

Different eel farms have different kinds of eels (referring to Japanese eels and European eels), but the symptoms of sick eels are basically the same: the body surface of sick eels is black and white, with annular striped spots, some seriously ill eels have red pectoral fins, swollen anus, gently pressing gill cover and yellow pus flowing out; Visceral anatomy, liver whitening (partly related to medication), gallbladder enlargement, gastrointestinal emptying, congestion of the outer wall, and severe abdominal hematocele; When the gill cover is removed, the gill filaments of most diseased eels are in the shape of white stripes and white stripes, and the gill filaments of the second or third gill flap have a large defect, and a layer of dirt such as mud is attached to the defect gill filament wound. Scrape off the dirt, cut off the gill filaments at the defect and examine them under a low-power microscope. After careful observation, we can see that the branched gill mold silk is attached to the gill of the sick eel.

In addition, in some eel farms, due to the incomplete treatment of parasites in the early stage, rotifers (the epidermis on the body surface will also be parasitic) or dactylogyrus infection may appear on the gill filaments.

therapeutic method

For the treatment of comprehensive gill diseases, it is generally to kill parasites first, then treat gill mold, and finally treat bacterial diseases. However, according to the degree of eel disease in different eel farms, some steps should be properly selected in the subsequent treatment process.

1. Treating bacteria

When it is determined that gill mold is no longer the main pathogen by microscopic examination or judging the number of dead eels caused by medication, bacterial treatment can be carried out. First of all, Prozac (10% florfenicol) 7g/ time for continuous medicinal bath twice, 24 hours each time;

Finally, use "povidone iodine" or other iodine preparations to bathe twice continuously to prevent the secondary infection of pathogenic bacteria.

During the whole treatment, if eels have appetite, it is best to keep feeding, but the daily feeding rate should be controlled between 1.0%- 1.2%. At the same time, add "VC"1.5g/kg, "ve"1g/kg, and "Radix Isatidis granules" 5g/kg. Every time sewage is discharged, it should be completely discharged. The dead eels in the pond were fished out in time.

Illness is inevitable when eel is cultured. It is the key to treat the disease to judge the symptoms in time and correctly and determine the cause. Some eel farms treated by the above methods have achieved very obvious effects on the popular eel gill disease.

2. Parasitic infection

Slice the gill of diseased eel, make it into glass, and observe it under low power microscope. If there are more than 5 Dactylogyrus or 10 trochanters in a visual field, the parasites must be treated first.

(1) Dactylogyrus:

Bath with "potassium permanganate" 1.5g/m for 2 ~ 3 hours;

Then change a lot of water (more than 80%);

Then use 0.5g/m+ 1.2g/m "Muwangwang" for continuous medicinal bath for more than 36 hours.

If there are many giant salamander larvae, use 0.5g/m "AEZ-Insecticidal King" (Wuxi) and 0.6g/m "Ousan" (Xiamen) for continuous medicinal bath for more than 36 hours.

If eels are particularly weak in the severe period of onset, use potassium permanganate 1.8g/m "Insecticidal Ling ц" (Chengdu) 3g/ m3 for continuous medicinal bath for more than 36 hours.

During pest control, the number of eel deaths may increase, but it is very beneficial to continue treatment after pest control. In addition, it usually takes more than 72 hours to kill the giant salamander, but considering the main cause of eel death, after 36 hours of medicinal bath, if the giant salamander is properly reduced or controlled through microscopic examination, the following gill mold treatment can be carried out.

(2) Worm gear:

Use "potassium permanganate" 1.5g/m 2 ~ 3 hours.

Then change a lot of water (more than 80%);

Then use Der Blaue Engel or angel blue (copper complex) 1.5g/m+ baichongsha (formaldehyde concentrated solution) 1.5g/m for continuous medicinal bath for 24 hours.

Step 3: treating gill mold.

First, salt 1‰+ baking soda 1‰+ methylene blue 2.5g/m for two days, and then changed a lot of water.

Followed by "Der Blaue Engel" or "Angel Blue" 1.5g/m+ "Viral Net" (single chain quaternary ammonium salt) 1.5g/m 2 days (1 day), (these two drugs are best used in sunny mornings);

Finally, "Antekang" (double-chain quaternary ammonium salt) was bathed in 0.7g/m for 2 ~ 3 times, 24 hours each time.

If the eel's condition recovers obviously, you can consider using 2.5g/m methylene blue for 2 ~ 3 days, or do it again according to the above process. In addition, in the treatment of eel diseases, in some eel farms, except parasites, the main pathogen is gill mold, which has been treated with gill mold, and eels can fully recover.

Eel fry breeding is a production process of raising eel fry to more than10g. At this stage, three different types of ponds are needed for aquaculture, namely, primary pond, secondary pond and tertiary pond. Eel species are the basis of adult eel culture, and the quantity and quality of eel species directly affect the quality of adult eel culture. Therefore, in order to develop eel production, we should first pay special attention to the cultivation of eel fry.

In order to ensure the smooth progress of eel fry cultivation, in addition to all the above preparations, the following production links need to be grasped.

First, the stocking density of eel fry

Due to different breeding methods, the stocking density of eel fry is also different. In general, the stocking density of the check pond is150 ~ 300 g/m2, and that of the flowing pond is 500 ~1000 m/m2. Low density stocking grows faster and has a high survival rate.

Second, the stocking time of eel fry

Since eel fry can only start feeding and growing when the water temperature is above 15℃, it is more suitable to cultivate eel fry in an open-air pond when the natural water temperature is above 13℃. In this way, eel fry can be domesticated when the water temperature rises after short-term temporary cultivation to adapt to the environment. The stocking time of eel fry in Guangdong and Fujian is around the beginning of March.

In eel farms with heating conditions or warm water supply, eel fry should be stocked as early as possible, which can prolong the feeding cycle and improve the yield and quality of eel species.

Thirdly, counting and weighing eel fry.

In order to control the stocking density of eel fry, it is necessary to count and calculate the weight, specifications and mantissa of each primary pond. The specific method is as follows: firstly, gently stir the eel fry in the cage, then randomly sample for 2-4 times, weighing 50g each time, put the eel fry into the sea and count them with a small bowl or spoon, and then calculate the average specification. Finally, the number of eels per kilogram is calculated and the average specification is obtained.

Fourthly, the adaptation of eel fry to the environment.

After long-distance transportation, eel fry are in a state of fatigue, and the temperature difference between the fry transport container and the pond is too large (especially in the heated breeding pond), which requires an adaptation process. The specific method is as follows: put the eel seedling box by the pond, gradually drench the eel seedling box with pond water, and put it into a cage placed in the pond in advance when the temperature of the eel seedling is close to the pond water temperature (generally, the difference is less than 5℃); If the nylon bag is used to transport oxygen, the nylon bag can be put into the pool first, and then the bag can be unpacked and put into the cage when the temperature of the bag is close to the temperature of the pool water. Generally, eel fry are temporarily cultured for 30 minutes to 1 hour (the aerator is turned on). After normal activities, the dead fry and dirt are skimmed, weighed and counted respectively, and put into each eel fry culture pond.

V. Disinfection of eel fry

Eel fry are delicate in constitution, and are easy to be scratched during harvesting, temporary rearing and transportation, and infected with water mold and bacterial diseases. Therefore, it must be disinfected when stocking. The disinfection method is medicated bath, one is medicated bath in the container, and the other is medicated bath splashed all over the pool.

Disinfection steps and methods: when using container medicine bath, it is usually carried out in a large water tank, so it is also called cylinder bath. Specifically, 300-400 kilograms of clean water is first put into the tank, then it is dissolved in a small amount of water according to the dosage ratio of drugs, and then it is poured into the tank, and the aerator is turned on to aerate, and the water is continuously stirred, so that the liquid medicine is evenly distributed. Then weigh about 5 kilograms of eel fry and soak them in the liquid medicine for 10- 15 minutes, and then take out the eel fry and stock them. At night, the whole pool was splashed with medicinal baths. After the medicine is dissolved, it is directly poured into the primary pool, and the aerator is turned on to stir the water, so that the liquid medicine is evenly distributed.

Disinfecting drugs and concentration: commonly used drugs mainly include methylene blue and salt.

Disinfection time: the medicinal bath in the container is carried out before the eel fry enter the pool; On the night after the eel fry entered the pond, the whole pond was sprayed and disinfected.

Open-air farming without water supply is the main farming method in China. The scale of eel farm is 50 mu. Breeding facilities mainly include eel ponds, water injection and drainage systems and ancillary facilities. Use rivers, lakes, reservoirs and groundwater as water sources. Generally, only110 ~1/7 of the pool water is exchanged every day. The water quality is mainly improved by floating cyanobacteria and increasing oxygen by waterwheel or aerator. Its advantages are low cost and low power consumption. The disadvantage is low yield, generally only 1000 ~ 2000 kg per mu.

1. Breeding facilities

(1) Specification of eel pond

Eel ponds can be divided into primary ponds, secondary ponds, tertiary ponds and adult eel ponds. The ratio of these ponds in the eel farm is 2: 8: 15: 75 respectively, that is, an eel farm with a water surface of 50 mu, a first-class pond 1 mu, a second-class pond of 4 mu, a third-class pond of 7.5 mu and an adult eel pond of 37.5 mu. The purpose and specifications of these pools are as follows.

Primary pond: it is used for feeding training of eel fry. The eel fry is raised to about 0.2g. The area is 50 ~ 60m2, the pond depth is 0.8 ~ 1.0m, and the water depth is 0.5 ~ 0.6m. ..

Secondary pond: raising eel species weighing 0.2 ~ 2g. The area is 200 ~ 400 square meters, the pool depth is 1.2 ~ 1.5m, and the water depth is 0.8 ~1.0m. ..

Three-level pond: feeding eel species weighing 2-20g. Covering an area of 400 ~ 800 square meters, the pool depth is 1.4 ~ 1.5m, and the water depth is1.0 ~1.2m. ..

Adult eel pond: the eel species weighing about 20g are bred into150 ~ 200g edible eel. The area is 800 ~ 1200m2, the pool depth is 1.5 ~ 1.6m, and the water depth is1.0 ~1.2m. ..

⑵ The shape and structure of eel pond

The shape of eel ponds at all levels should be round or square, with four corners cut off. According to the characteristics that eels are easy to escape, difficult to catch and have high water quality requirements, they must have the functions of escape prevention, easy to catch and convenient for water injection and drainage. The wall of the pond can be made of stone and brick slurry, cast-in-place concrete and precast concrete slab. The walls around the pond are vertical and smooth, with a height of 0.8 ~ 1.6 m, and the top of the wall is "pressed" by a cover plate, which extends into the pond for 5 ~ 10 cm, and the dike surface is 0.3 ~ 0.5 m higher than the water surface. The bottom of the pool has two kinds: pot bottom and flat bottom, which require hardness and impermeability. The bottom is paved with 20 cm thick stone slag, raked flat and compacted, and then paved with 5 cm thick yellow sand for joint sealing. Cement mortar should also be used to wipe the bottom of the first-class pond to collect seedlings. The bottom of the pot is located at the lowest point in the center of the pool bottom, and the flat and low pool bottom is inclined to the drain, and the water inlet and the drain cross each other. The water injection port is arranged at the top of the pond wall, which is 20 ~ 30 cm higher than the highest water level of the pond and extends into the pond for about 30 cm; The drain port is opposite to the water injection port, and there are three gates around it; The first net door plays the role of escape prevention, using stainless steel mesh or polyethylene mesh. Its mesh size is eel seedling pond 1 ~ 1.5 mm, eel seedling pond 1.5 ~ 2 mm and adult eel pond 2 ~ 4 mm The bottom of the second gate or black box is suspended, and the sewage at the bottom is pressed out. The third gate acts as an overflow to keep the water level in the eel pond constant.

Eel ponds require high water quality, not only the water injection and drainage systems of each pond are required to be separated, but also the water sources of water injection and drainage of the whole eel farm must be strictly separated. Otherwise, it will cause self-pollution due to the death of eel feces and a large number of microcystis, leading to serious death of eels.

(3) Food shed

Eels like to feed in the dark, so food sheds (including food tables, food fields and shade sheds) should be set up beside the pool in the lee of the sun. The dining table is a rectangular frame of 90 cm× 45 cm× 20 cm, and the bottom of the frame is stretched with nylon mesh, and the mesh size allows eel species to pass freely; The feeding field is located at the bottom of the water below the feeding platform, and it is covered with stone slag or snail shells, which is required to be firm and flat; Set up a sunshade above the dining table.

2. Eel culture

(1) eel culture

Eel breeding is a process of raising white eels with a weight of 0. 1 ~ 0.2 to small eels with a weight of 10 ~ 20g. In the second year, most eel species can be cultivated into edible eels (150 ~ 200g/ tail). The culture of eel fry is generally divided into three levels. The stocking specifications and densities of eel ponds at all levels are as follows: stocking 0. 1 ~ 0.2g eel fry per square meter in the primary pond and putting 0.3 ~1kg eel fry per square meter in the secondary pond; 2-20g eel species and 0.5-2kg eel species are stocked in the tertiary pond per square meter.

Selection of eel fry: high-quality eel fry requires wide head, blunt nose and neat specifications; Swimming is lively, the body is not traumatic, and the body color is bright and white; Rich skin, strong body, no pathogens parasitic. The specification is about 6000 tails per kilogram.

Eel fry stocking: the stocking time is from March to April, and it is more suitable when the water temperature is above 20℃. Before releasing the seedlings, the culture pond and eel seedlings should be disinfected with drugs. The disinfection method of the culture pond is the same as that of the family fry pond. Stocking density shall be carried out according to the requirements of primary pool.

Feeding training: Feeding training is the key technology of raising eels, and it takes about one month to train. In the first week after the eel fry enter the pond, we should try our best to change the feeding of eel fry from scattered feeding to centralized feeding. Generally, from the evening, the washed silkworms are scattered on the dining table, and fed 4-5 times a day, and the daily feeding amount accounts for 20-40% of the total weight of eel seedlings. At the same time, a 15W electric lamp was hung above the dining table to guide the eel fry around the dining table and concentrate on feeding. You can also build a canopy above the food table during the day to create a dark environment and induce eel fry to eat. A week later, if most of the eel fry are led to the food table for feeding, it means that the centralized feeding training has been successful. Then gradually postpone the feeding time, and finally completely change to daytime. From the second week, the feeding amount of earthworm was gradually reduced, and the minced meat of fresh feed such as mussel meat, pig spleen or fresh fish was increased four times a day, and the daily feeding amount accounted for 10 ~ 15% of the total weight of eel fry. After 15 days, earthworms or minced meat gradually mixed with compound feed, and the proportion of compound feed gradually increased. After 1 month, all eel fry can be fed with compound feed, and the daily feeding amount accounts for 5 ~ 8% of the total weight of eel fry. The compound feed should be fully rubbed with water, and appropriate amount of oil should be added if conditions permit. Feed immediately after stirring to prevent α -starch from cracking and affecting adhesion.

Graded feeding: Due to the different competition for food, the individual size of eel fry varies greatly. Therefore, eels of different specifications should be separated every 20 to 30 days, and no food should be eaten the day before separation. Because the eel is still young, it can be fished under the table with dense eyes in the first few times, and the strong seedlings that are served first are divided first; In the future, as individuals grow up, they can be sorted by Guangdong fishnet or knottless nets with different mesh numbers. After finishing, take a bath with furazolidone, which can be cultivated according to grades. The stocking specifications and densities of seed ponds at all levels are as mentioned above. The daily consumption of eel compound feed after single culture is 3 ~ 5% of the total weight of fish. Most of the eel fry can grow to about 20g when they are raised in the middle and late period of 1 1, so they can be put into eel ponds as eel species.

Water quality control: managing the water quality of eel pond is a reliable guarantee for high yield of eel.

The main measures are:

① Culture Microcystis to increase dissolved oxygen in water. Because the source of dissolved oxygen in eel pond water mainly depends on the microcapsules in cyanobacteria through photosynthesis, when the number of microcapsules in pond water is small and the transparency is too high, the species of microcapsules should be fished out from the nearby pond and put into eel pond, and ammonium sulfate should be applied at the dosage of 0/.0 ~1.5 kg per mu for 2 ~ 3 days, and strong chemical fertilizer should be applied.

② Master the color of water. The pool water should be kept thick with green palladium, and the transparency should be about 25 cm. When the water color changes from strong green to light green or light yellow, or the transparency is greater than 25cm, ammonium sulfate should be topdressing in time, 0.5 ~ 1kg per mu for 2 days. When there are too many Microcystis, the color of the water is too thick, and the transparency is less than 15cm, new water should be injected to increase the transparency to about 25cm.

(3) timely control of pests and diseases. Zooplankton is the enemy of Microcystis, especially rotifer. In order to limit the reproduction of rotifers, a certain number of bighead carp can be raised in the eel pond, and generally 10 ~ 20 heads can be raised per mu. If zooplankton still reproduce too fast, crystal trichlorfon can be sprinkled to make the concentration of pool water reach 0.5 ~ 1ppm.

(4) Start water injection in time. In order to improve the water quality of eel pond, a waterwheel aerator should be installed to aerate, and the start-up time can refer to the domestic fish farming part. At the same time, change the water from110 to 1/7 every day. When changing water, the residual bait and feces in the pool water should be discharged outside the pool.

⑵ Adult eel culture

Adult eel breeding is the production process of developing eel species weighing more than 20 grams into commercial eels weighing 150 ~ 200 grams. Adult eel culture has two forms: specialized culture and mixed culture.

Pond characteristic culture: it is to raise eels in high density in the pond, and the average yield per mu in the open-air pond is more than 1000 kg.

Feeding eel species: before feeding eel species, the eel pond and eel species should be disinfected with drugs and then put into the eel pond for feeding. The stocking time is generally from the middle and late March to the early April, when the water temperature is above 65438 03℃. The stocking density is determined according to the yield index, eel pond conditions, eel species specifications and culture techniques. Generally, the stocking quantity with yield per mu 1000 kg or more is about 20 grams of eel species, with yield per mu 150 ~ 200 kg; The specification is about 50 grams, and the yield per mu is 300 ~ 400 kilograms. The stocking density of the semi-mobile pond can accommodate 3-5 kilograms of eel species weighing about 20 grams per square meter, and the well-equipped mobile pond can accommodate 10- 15 kilograms per square meter.

Feeding management: Feeding management mainly includes feeding feed, round catching and round releasing, water quality management, fish disease prevention and control, etc.

There are two kinds of feed for raising eels: fresh feed and compound feed. The feeding method adopts the principle of "four fixed". Feed it once every morning at 9 ~ 10, and the daily feeding amount is 25℃. The compound feed accounts for 2 ~ 5% of the total weight of pond eel, and the fresh feed accounts for 10 ~ 15%. When the water temperature is low in early spring or late autumn, or when the water temperature exceeds 30℃, the daily feeding amount can be reduced as appropriate. Feeding is generally required within 20 minutes. The eel material should be gently stirred evenly. Feed immediately after stirring.

In the process of feeding, the growth rate of individuals varies greatly, so it is necessary to take measures such as stocking in stages, fishing in stages, catching the big ones and keeping the small ones, and catching the big ones to make up for the small ones. Generally, the eels in the same pond are graded and sparsely cultivated once every other month or so, so that the eels in the same pond have neat specifications and reasonable density. Some eel species released at the end of March have reached the market specifications in early June and can be caught for the first time; After June, when the water temperature rises, eels want to be vigorous and grow fast. The second fishing can be carried out in late July, and eel species will be supplemented immediately after fishing. At the beginning of September, a considerable part of them reached the listing specifications for the third fishing; Fishing in ponds was carried out in mid-June165438+1October, and eel species that did not meet the market specifications were reserved for fishing in the following spring. Stop feeding, change the pond water, suspend the original pond, empty the food in the stomach, and then screen the eel with smooth fish. Be careful when operating to prevent fish from being hurt.

Water quality management The water quality management measures of jujube trees can refer to the practice of seedling stage.

Mixed culture of jujube in pond There are two ways to mix eel in a fish pond with four big fish: no eel feed and eel feed. The former is equipped with 50 ~ 100 eels per mu 15 ~ 20g. Eels feed on wild fish and shrimp, benthos and fish pond feed scraps, and can catch 10 ~ 15kg weight 150 ~ 200g edible eels at the end of the year. The latter is a high-density polyculture, with/.5 ~ 20g eel species per mu/kloc-0, once a day/kloc-0, 000 ~ 2,000 eels, and the feeding amount is 1 ~ 2% of the total weight of eels. Eels can also eat wild fish, shrimp and benthos in the pond. At the end of the year, you can catch 150 ~ 300 kg of edible eels. These two polyculture methods have been widely popularized in the Pearl River Delta of Guangdong Province, which has significantly improved the economic benefits of fish ponds.

Raising eels in warm running water is an advanced method. It is required that the water temperature should be controlled at the optimum water temperature for eels (about 27℃), and the eel should be cultured in flowing water. Its advantages are less eel diseases, fast growth and high yield per unit area. Generally, when seedlings are released at the beginning of February, all edible eels can be cultivated in that year, and the yield per mu is about 15000 kg. Disadvantages are large capital investment and strong breeding technology. Due to different water sources, this culture can be divided into two types: waste heat temperature drainage culture in factories and indoor circulating filtration culture. The former uses the waste heat of the factory to drain water, which can save energy, has simple structure and low breeding cost; The latter is heated by a boiler, and the pool water is recycled, so it is necessary to build a biological filter, which has a complicated structure and a large one-time investment.

In order to automatically inject water and drain water, it is required to build an eel pond by using the terrain elevation as much as possible. Because the pool water is discharged from the field immediately after use, it is generally operated in the open air. Its main facilities are: hot and cold water pipes, temperature regulating pools, eel ponds and drainage pipes.

The circulating filtration eel farm is generally operated indoors and equipped with a biological filter pool. The scale of warm-water eel farms is generally 1 ~ 2 mu. Each pond is made of cement, with an area of 30 ~ 50m2, a depth of1.2 ~1.4m and a storage capacity of1.0 ~1.2m.. The pool is round or square with four corners cut off, and the bottom of the round pool is the pot bottom. The drainage outlet is located in the center of the pool bottom, and consists of two semicircular drainage piers and three gates on both sides of the piers. The bottom of the square pond is flat and inclined to the drain. Other equipment requirements and feeding management methods are basically the same as those of open-air ponds.

Water quality management "water" is the lifeblood of eel industry, and good water quality management is the top priority of aquaculture in high temperature season.

1. Artificial cooling method. To reduce the water temperature, we can also achieve the purpose of reducing the water temperature by artificial soil without relying on "air conditioner" or "electric fan". The method is: 1. Cover the intensive culture pond with a layer of black shading cloth, so that the shading cloth can not only ventilate, but also block the direct sunlight, increase the cooling of the water surface, and reduce the water temperature by about 1 ~ 2℃. 2. Change the sewage in advance. Under normal circumstances, sewage is discharged at 8: 00 a.m. to change water, and the high temperature season can be advanced to 6: 00 a.m. because the water body is relatively cooler at night than during the day. When the water temperature is low, the purpose of lowering the water temperature can also be achieved by discharging sewage and changing water. 3. Raise the water level. In high temperature season, the water level will rise to the highest boundary in both soil ponds and intensive ponds. High water level, large water space and slow heating are also good ways to cool down. 4. Increase the amount of water exchanged. When the temperature is the highest at noon, adding some cold water to the pool by using mechanical wells or deep wells can also achieve obvious cooling effect.

2. Flood elimination method. The high temperature season is also a season of frequent rainstorms. Eel farms often suffer from eel poisoning, insect pests, gill rot and other diseases due to floods. How to avoid flooding the pool: 1. Whenever there is a rainstorm, it is better not to feed, pollute or change water. It is better to feed a meal less than to risk flooding. 2. What if there is a little flood in the swimming pool? Once there is a little flood in the pool, use potassium permanganate 1.5ppm to adjust the water quality, or use quicklime 15 ~ 20 ppm to improve the water quality, or use water purification treasure 3ppm to purify the water quality. 3. Adjust and change the time of sewage discharge and water exchange, and stagger the opportunity of direct contact with flood. During the flood period, sometimes sewage can be discharged in advance for water exchange, and sometimes sewage can be delayed for water exchange, which is not subject to conventional restrictions and tries to avoid flooding into the pool. 4. what should I do if a large number of floods enter the pool? Once a large number of floods occur in the pond, feeding should be stopped first, then water quality improvers such as Haizhongbao should be used for purification, and finally 2 ppm+ potassium permanganate +2# pesticide should be used for pest control, sterilization and disinfection.

Water stopping in greenhouse is a cultivation method matching with open-air pond. A steel frame is placed above the culture pond, covered with plastic tiles or films, and heating measures are taken to keep the pond water at about 25℃. The specifications, stocking density and management methods of eel ponds at all levels are basically the same as those in open-air ponds. Eel fry can be separated into ponds after being raised for about one month, and the survival rate is about 80%. The eel fry released in late February can be reared for 120 ~ 150 days, and 3 ~ 5g eel species can be reared. At the end of the year, about 50g eel species can be reared, and 20 ~ 30% eel species can be reared for food.

The eel cultured in earthen ponds, also known as white eel and white loach, is a rare fish cultured in fresh water. It has tender meat, delicious taste and high nutritional value, and has the medicinal effects of removing blood stasis, promoting tissue regeneration, nourishing and recuperating. Eels grow rapidly and have strong adaptability, and can live normally even in waters where there is little dissolved oxygen and other fish can't survive. The technical requirements of artificial breeding are not high, and the feed sources are extensive. A large number of eel farmers have cultivated in soil ponds, all of which have achieved high yield and high efficiency. Eel species can be listed in late autumn and early winter, with an average yield of 800 ~ 1000 kg per mu. The key technologies of high-yield and high-efficiency eel culture in soil ponds are introduced as follows:

I. Selection and disinfection of ponds

The earthen pond for raising eels should be ventilated and sunny, with sufficient water resources, and the area should not be too large. Planting water hyacinths or water peanuts with a width of 0.8 ~ 1 m around the soil pond and enclosing them with fences or nets can not only prevent the eels from escaping, but also provide shade for their growth.

Before stocking, the excessive silt in the land should be removed, the bottom of the pond should be leveled, the ridge and the entrance and exit of the pond should be repaired, and the pond should be cleaned and disinfected 10 ~ 1000 square meters 125 days before the eel is raised in the pond, so as to completely kill wild miscellaneous fish and enemy creatures. Then water with a depth of 0.6-0.7m is injected 5-7 days before the eel enters the pond, and the water inlet is filtered by a 60-mesh screen. Finally, apply base fertilizer. Generally, 300 ~ 400 kilograms of decomposed pig cow dung is poured every 1000 square meter. After the water is light green or yellowish brown, the eel species are released so that they can eat enough natural bait after entering the pool. /kloc-deepen the pool water to 1.5m in about 0/5 days.

2. Treatment and release of eel species

The suitable temperature for eel growth is 20 ~ 28℃ and the water temperature is 65438 02℃, so the release time is generally from late February to mid-March. Soak eel seeds in water for 20-30 minutes before putting them in the bag to adapt to the water temperature. Only when the temperature difference between the inside and outside of the bag is less than 5℃ can the bag be opened, and then 2-3 pots of water are poured into the bag with a small pot, so that the eel fry can gradually adapt to the low dissolved oxygen state from the high dissolved oxygen state. At the same time, the eel species should be disinfected before being put into use, and the eel species should be soaked in 0.75 ~ 1 kg salt 15 ~ 20 minutes every 50 kg of water.

The released eel varieties should be bluish gray in color, thick in skin, elastic and active in swimming, and the specifications of eel varieties in the same pond should be neat and consistent, otherwise the competition among eels will affect the feeding of individual weak people. The stocking density is generally about 4000 ~ 5000, with 20 grams per 1000 square meter; About 50 grams can throw 3000 ~ 4000 tails; About 100g can be put into 2000 ~ 3000 tails. At the same time, 50 bighead carp, 30 silver carp and 200 tilapia can be mixed in every 65,438+0,000 square meters soil pond, which can filter plankton, eat feces excreted by eels and purify water quality. On the other hand, it can increase fish production.

Three, feed types and feeding

Eel artificial breeding mainly relies on special compound feed (available in the market), and 50-60 grams of multivitamins (vitamins A, B, C and E) and 1.5-2 kilograms of cod liver oil are added to every 50 kilograms of special feed (cod liver oil should be stopped when the water temperature is lower than 20℃ or higher than 35℃). Young eels should be added less and adult eels should be added more. If there is a temporary shortage of special feed, animal feed such as small miscellaneous fish, internal organs of livestock and poultry and silkworm chrysalis can be ground and mixed with flour to replace it, and its crude protein content must be above 40%.

Eels are carnivorous fish and greedy. When feeding, we should implement the principle of "four determinations", that is, qualitative, quantitative, timing and positioning. Quality decision: that is, to ensure the quality of feed. The prepared feed should be moderate in hardness (water addition is 1.2 ~ 1.3 times), fresh and clean, and cannot deteriorate. Quantification: that is, according to the specifications, feeding, digestion, weather, water temperature and water quality of eels, the feeding amount should be appropriate. Generally, the daily feeding amount is 65438+ 0.5% ~ 2.5% of the eel's weight, and it is appropriate to eat it within 12 hours. Timing: The fish is small in size and high in density, and it is fed at 8: 00 am and 4: 00 pm every day 1 time; The size of eel is above 1 00g, and it can be fed1time from 8: 00 to 9: 00 every morning. Positioning: that is, the feed is placed on a fixed food table, and 2 ~ 3 food tables can be set up per 1000 square meter soil pool.

Fourth, daily management and disease prevention.

Patrol the pond every morning and evening to observe the activities and feeding of eels, and check the drain after rain to prevent the fish from escaping. Add fresh water 1 time every 10 ~ 15 days at ordinary times, and add fresh water 1 time every 5 ~ 7 days in summer and autumn, and the water exchange rate is about 10% of the whole pool. At the same time, pay attention to make the pH value between 7 and 8.5. If the pH value is too high, fresh water should be replaced; if it is too low, it should be adjusted with 15 ~ 20kg quicklime per 1000m2.

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