CATDOLL : CATDOLL: As the saying goes, "Qingming snails are as fat as geese." When eating snails at this time, you should be careful and stay away from a poisonous snail.

1. As the saying goes, "Qingming snails are as fat as geese", you should be careful when eating snails at this time and stay away from a kind of poisonous snails

The annual Qingming Festival is here again. In addition to worshipping ancestors, eating seasonal delicacies is also an indispensable tradition. In the spring when Qingming Festival is approaching, many people will go to the waterside to catch snails to eat, because the snails before Qingming have just finished wintering and will eat a lot before preparing to lay seeds. At this time, the snails are tender and big in size, and taste tender and plump. It is the best time of the year to eat snails.

After the Qingming Festival, the snails will start to lay eggs, and there will be small snail eggs inside the shells. They taste like a pile of small sand and the taste is much worse. Therefore, there is a saying among the people that "Qingming snails are as fat as geese". If you want to eat snails, you have to take advantage of the Qingming Festival.

When cooking snails, we usually like to stir-fry or marinate them. Both the shell and the meat are very tasty. Many people like the process of picking the meat and sucking the shell, which is very interesting.

In addition, snails have certain medicinal effects. Snail meat is sweet, cold, non-toxic, and has the effects of removing dampness and detoxification, clearing heat and relieving pain, and promoting diuresis and relieving stranguria. "Compendium of Materia Medica" also records that snails can eliminate dampness and heat and treat jaundice.

How about this? Are you drooling after hearing this? Do you want to buy a few pounds of snails to eat right away? Don’t be in a hurry. There are a few things you should pay attention to when eating snails. Don’t turn a delicious delicacy into poison.

Snails vary in size and quality, so in the past, many businesses would choose to use larger apple snails that appear to have more meat.

The golden apple snail was originally an invasive species. It looks very similar to field snails, has a wide diet, is highly adaptable, grows and reproduces quickly, and has a high yield.

However, golden apple snails contain a large number of parasites, such as Angiostrongylus cantonensis. According to statistics, there are 3,000 to 6,000 parasites in just one golden apple snail. People who eat undercooked golden apple snails may be infected, which can cause malignant diseases such as eosinophilic meningitis and meningoencephalitis, causing symptoms such as headache, fever, stiff neck, facial nerve paralysis, and in severe cases paralysis or even death.

In order to completely kill the parasites in the body of the golden apple snail, it must be heated for at least 20 minutes. After a long period of cooking, the meat of the golden apple snail will become very tough and have a bad taste. In order to maintain the taste, most chefs cook the golden apple snail for 5 minutes before serving it on the table. The risk of infection with parasites after accidental ingestion is very high.

This caused a large number of food safety poisoning incidents in the past few years, so the golden apple snail was removed from everyone's food list.

But after the public forgot about this incident, some unscrupulous merchants secretly cooked and sold golden apple snails for profit. Therefore, when eating these aquatic products, you must choose regular restaurants and pay attention to observe. If the size is larger than ordinary field snails and the color is darker, it may be golden apple snails.

In addition, when you cook it yourself, you must cook it thoroughly, and it is recommended that you do not choose to eat apple snails.

Friends, do you like to eat snails? Do you know which species of snails are not edible? Please leave a comment in the comment section below to share your life experience.

2. Can I put some apple snails, river snails, loaches, or fish in the tank?

Snails, loaches, and eels are all famous aquatic species, especially the latter two, which are now being cultivated on a growing scale. They are cultivated all over the country, and the breeding benefits are also good. These three species can be mixed in the actual breeding process, but it is better to breed one of the latter two species as the main species and then mix them with snails. The following is a detailed explanation:

1. Living habits: Eels are benthic species with strong adaptability. They can survive in all kinds of freshwater waters. They are more numerous in still waters such as lakes, rice fields, ponds, ditches, ponds, reservoirs, etc., and also in slow-flowing streams and rivers. They like to live in the bottom of the water with a lot of humus, and often drill into the mud bottom or the cracks in the crevices of field embankments, dikes and rocks by the water to live in caves. Loaches also like to live in ditches, lakes, ponds, and rice fields. When the water temperature is too high or too low, they dive into the mud. In addition to breathing with gills, loaches also breathe with skin and intestines. When the weather is muggy and there is a lack of oxygen in the hot water, they float to the surface of the water to swallow air and expel waste gas from the anus. Snails generally live in shallow rice fields, ditches, ponds, and lakes. When the water is too shallow or the water temperature is too low, they will also dive into the mud and soil.

2. Food habits: Eel is a carnivorous species, usually feeding on small fish, shrimp, earthworms, aquatic insects, etc.; feeding earthworms under artificial breeding conditions has a better effect, and it can also be fed with clam meat and livestock offal; many large-scale breeding now domesticates it to eat granular feed. Loach is an omnivorous species, and its bait includes zooplankton, small crustaceans, insects, flat snails and higher plant debris; when artificially bred, it can be fed with rice bran, bran, bean cakes, snails, earthworms, silkworm pupa powder and feces. Snails generally feed on humus and organic debris at the bottom, and organic fertilizers are mainly applied under artificial breeding conditions.

From the living habits and feeding habits of the above three species, it can be seen that there is no big conflict in co-breeding them. Only when the size of the eel is too large and the size of the loach is too small, there may be residual cannibalism. There is no big conflict in feeding habits when the sizes are similar. However, the eel and loach are both benthic or burrowing species, so it seems unnecessary to breed them in the same pond. It is more ideal to breed one of them with field snails. The field snails can make full use of the residual organic matter and residual bait in the breeding water, and the bred small field snails can also be used as feed for the eels and loaches, which is mutually beneficial.

If you raise field snails together with other species for direct marketing, it is also a good idea, but you must pay full attention to the density of the three species; if your purpose of raising field snails together with other species is to use them as feed for eels and loaches, it is best to raise the golden apple snail (i.e. apple snail) which has stronger fertility, faster growth and stronger adaptability. This method is the most commonly used one among breeders; or you can raise earthworms as bait in the open space on the bank of the pond.

3. How to culture eels without soil in cement pool?

Farming technology

1. Operation procedures of still water and soilless ecological breeding technology for yellow eel

The content of the still water and soilless ecological breeding technology of rice field eels is quite extensive. The key technologies include the shallow water semi-artificial breeding technology of rice field eels, the rapid domestication technology with compound feed, and the disease and pest control technology. Among them, the screening and processing of eel species are the key to the success of rice field eel breeding.

2. Construction and treatment of eel ponds

The construction of eel ponds should take into account the following five design principles: simulate the natural environment; convenient drainage and irrigation, conducive to heat preservation; conducive to taming and feeding compound feed; conducive to the prevention and control of eel diseases and pests; escape prevention, easy capture and convenient management. The area of ​​outdoor static water soilless breeding ponds is 15-20m2, and the indoor breeding area is smaller, generally 6-10 m2. Pool wall height: 20-30cm indoors, 40-50cm outdoors. The wall can be built with a single brick, cement is applied inside, and the top of the wall is horizontally built with bricks in a "T" shape. Plastic film pools can also be used for breeding. Several small pools of the same specifications are strung together in a row, but the inlet and outlet are independent to prevent diseases and pests from spreading to each other. The shape of the fish pond is preferably rectangular or square. The outlet is slightly lower than the bottom of the pool to ensure thorough sewage discharge; the water inlet is set just above the food table, opposite to the outlet, and the position should be high, generally 15-20cm from the bottom of the pool; the overflow outlet is 25cm from the bottom of the pool, and the overflow outlet is not required for indoor breeding. The diameter of each water outlet is about 5-6cm and should be covered with a nylon net to facilitate the discharge of feces and prevent the eels from escaping.

After the cement pool is built, it must be de-alkali treated. Using a new pool without de-alkali treatment is one of the main reasons for the failure of many farmers. The method is: soak it with phosphate fertilizer (1 kg of phosphate fertilizer for 1 ton of water) or acetic acid for a week, drain the soaking water and replace it with clean water; or fill it with water and soak it for 30 days (it is best to put grass piles to ferment), and then drain it. Plastic film pools do not need to be de-alkali treated.

Fish nests are very important in static water and soilless culture. Various pipes, bamboo tubes, brick gaps, water plants, etc. can be used as fish nests. Since eels have a certain degree of aggregation, the area of ​​the fish nest should not be too small. The general principle of setting up eel nests is: it is convenient for eels to enter and exit freely, the interior is dark and lightless, and there is enough space. In production, it is generally better to use waste bicycle tires disinfected with potassium permanganate solution as eel nests. The tires are placed under the water plants, and 5-6 tires can be placed in each small pool. Bamboo tubes of about 2m can be used. The size of the hole depends on the eel body. It is appropriate to be larger than the eel. Every two bamboo tubes are in a row, and each pool has 3-5 rows, with a spacing of about 0.3m between each row. Bricks are placed under each row of bamboo nests to make a large space under the bamboo nests, which is convenient for water flow and sewage discharge. In order to fix the bamboo nests, it is best to press bricks above the hole, which also plays a role in shading and shading.

3. Aquatic Plant Stocking

"To raise fish, you must first raise water, and to raise water, you must first raise grass." The placement of aquatic plants is one of the key technologies for static water soilless aquaculture. Reasonable placement of aquatic plants to purify water quality can reduce the number of water changes in the eel pond to once a month, saving water and labor, and can prevent heatstroke, reduce stress reactions, provide fish nests, and prevent diseases and insect pests. Aquatic plants are selected according to the standards of "preventing fish from escaping, growing fast, purifying water quality, and facilitating fish hiding." Common ones include water peanuts, water hyacinths, water lilies, and fine green duckweed. The planting area of ​​aquatic plants should not exceed 2/3 of the total pond area. At least 1/3 of the fish pond area should be left empty to set up a feeding table and facilitate the activities of yellow eels. In different seasons, aquatic plants should be reasonably matched in a certain proportion. In summer, water hyacinths and water lilies are the main ones, while in spring and autumn, water peanuts and fine green duckweed are the main ones. In winter, no aquatic plants are left to prevent yellow eels from freezing under the aquatic plants. Generally, aquatic plants are put in 15 days before stocking eels. Before putting in, they should be disinfected by soaking in 100g/m3 potassium permanganate solution for 0.5h, or by soaking in 10g/m3 copper sulfate solution for insecticide.

In daily management, excess aquatic plants should be removed in time or overly long aquatic plants should be cut. In combination with eel pond disinfection, 10g/m3 quicklime or 0.7g/m3 copper sulfate solution should be sprinkled on the grass to prevent aquatic plant pathogen infection.

4. Eel species selection

The key to successful eel farming is the quality of seedlings. At present, the large-scale breeding technology of eels has not yet been mastered, and the seedlings used in production are basically from wild resources. There are many ways to catch wild eels, including cage catching, hook fishing, electric shock, shovel digging, clamp catching, net lifting and drug catching. Some wild eels have been transferred and stored and transported many times, and some wild eels themselves carry diseases and insect pests. Therefore, the quality of wild eel seedlings purchased from the market is uneven, and strict screening is very important in production.

There are many methods for screening eel seedlings. The sensory screening method (based on body color, external injuries, strength, mucus, etc.), water flow screening method, behavioral screening method, and burrowing screening method are highly subjective and cannot screen eels with latent diseases in the body. It is also troublesome to screen them one by one. The drug immersion method is highly irritating to eels, the drug concentration is difficult to control, and the operation is also troublesome. The feeding screening method has a better screening effect, but there are no reports on its specific operation process and quantitative method.

The eel selection method we use in production is: put the eel seedlings in a shallow plastic container at a certain density, soak them in medicine, feed them a fixed amount of empty mealworm larvae for 5 consecutive days, change the water once every morning, and check the eel's food intake. In the range of 18-30℃, if the average daily food intake of the eel exceeds 0.5% of the eel's body weight, then keep the seedlings; if the average daily food intake of the eel is less than 0.5% of the eel's body weight, then eliminate the seedlings. The eel stocking time is generally 10-15 days after the water plants are put in.

5. Semi-artificial breeding technology of yellow eel

The semi-artificial breeding technology of the yellow eel has the advantages of high fertilization rate and hatching rate, concentrated breeding time, convenient management and high efficiency, and is an inevitable trend for the large-scale breeding of yellow eels. The breeding pond is designed and built according to the requirements of static water soilless breeding, with an area of ​​20-30m2. The types of aquatic plants vary from place to place, including water hyacinth (Eichhornia Crassipes Solm.), water peanut (Alternanthera Philoxeroides Griseb), water lily (Pistia stratiotes), and goldfish algae (Ceratophyllum demersum). From March to July each year, 10 parent eels are stocked per square meter of the breeding pond (female: male ratio is 6:4). The management method is the same as static water soilless ecological breeding, but the number of water changes is increased during the breeding season (May to August), that is, the water is changed once every 7 days, the water depth is 20-25cm, and the pH is 6.0-8.5. After the yellow eel lays eggs, it is promptly fished out for artificial incubation, and the unfertilized eggs should be removed in time. The drip incubation method is: the incubator is a shallow dish of 40cm×40cm×7cm, with 2cm thick sterilized river sand on the bottom, water drips in from a high container and overflows from the side wall of the dish, the water depth is kept at about 5cm, and the daily temperature difference does not exceed 2℃. When the fertilized eggs just enter the incubator, the water dripping frequency is 10 drops/min, which lasts for 24 hours, and then the water dripping speed is gradually increased until the seedlings are hatched.

6. Eel Taming

Rice field eels are very selective about food, and once they adapt to a certain food, it is difficult for them to change their eating habits. At present, the artificially cultured eels mainly come from wild eels that eat live bait. If they are fed with live bait alone, it is not conducive to the healthy growth of rice field eels, and it increases the input cost, and may be limited by the fact that feed resources cannot be available for a long time. If they are fed with compound feed or a small amount of live bait is mixed into compound feed, it is possible to effectively reduce feed costs, ensure comprehensive nutrition, facilitate the addition of additives and drugs, and prevent and control diseases and insect pests. Therefore, feeding compound feed is an important measure to develop the rice field eel farming industry.

1. Taming conditions

(1) The feeder must be patient. The feeding process takes at least 7-10 days. It is normal to succeed in feeding in 10-30 days.

(2) The eel pond should be small, generally 15-20m2. The eel feeds by using its sense of smell, taste and lateral line system in an integrated manner. The eel must be within an effective range to find and prey on food.

(3) Feeding training must be based on the four principles of “fixed location, fixed time, fixed quality and fixed quantity” that the eel can eat.

(4) Feeding should be done according to the season, weather and the size of the eel species. For example, it is very suitable for feeding eels when they just finish hibernation, the temperature rises and they start to feed.

(5) If it is a wild eel, the leeches should be carefully screened and killed, and the eel should be domesticated and eaten after being stabilized for a period of time.

(6) It is not advisable to release loaches or other fish into the water before taming the eels. Releasing them too early will cause them to compete with the eels for food, which will be detrimental to taming the eels.

2. Food Taming Method

Taking advantage of the eel's swallowing and greedy nature, live bait is mixed with compound feed for feeding training. The eel's start feeding time, peak feeding time and finishing time are required to be mastered to facilitate artificial feeding training.

(1) Before training, the eels must be starved for 1-2 days without being fed any food.

(2) Before starting to train the eels, feed them with live bait that accounts for about 1% of their weight for 2-3 days, such as river frogs, earthworms, mealworms, etc., and the "four determinations" must be achieved.

(3) After stopping feeding for another 1-2 days, make the compound feed and live bait into a "cake" style, that is, cut part of the live bait into pieces and mix it with the compound feed, and stick part of it to the outside, or use a dough press to press it into thin strips for feeding. The total amount is about 1% of the weight of the stocked eels. On the first day, it is 80% live bait and 20% compound feed, on the 2nd-3rd day, it is 60% live bait and 40% compound feed, on the 4th-5th day, it is 40% live bait and 60% compound feed, and so on. Generally, it will take 7-10 days for the eels to be fully tamed and eat artificial compound feed.

(4) During the feeding process, observe the leftover food, water quality and excrement every day to judge the feeding situation of the eel. If the feeding is abnormal, remove the leftover bait and reduce the proportion of compound feed or appropriately reduce the feeding amount. If the eel still cannot eat normally, stop feeding for 1-2 days and then continue. If the eel can finish eating, gradually increase the proportion of compound feed until the feeding is successfully trained. After the feeding is successfully trained, immediately mix drugs into the compound feed to kill parasites. For the eels that have been successfully trained, make the compound feed into dry granules the size of mung beans or peas and feed them. The total amount should also be gradually increased to 2%-10% of the eel weight, and then enter the daily management work.

7. Summer Shade

The still water soilless breeding pond for yellow eel is small (15-20m2), with shallow water level (about 15-20cm), and the water temperature can easily exceed 30℃ in summer. Shading is an essential step to avoid the heat. Generally, a shade net is set up on the pond, and climbing plants such as grapes, loofah, trichosanthes, and pumpkins are planted by the pond. But pay attention to leaving 10% to 30% of light on the surface of the pond. At the same time, when the temperature exceeds 33℃, the water level in the pond should be deepened to reduce the density of yellow eels, and new water should be slowly injected. Groundwater can be used to adjust the water temperature of the eel pond.

8. Water quality control

The pH value, transparency, dissolved oxygen, ammonia nitrogen, temperature, nitrite and sulfide of the aquaculture water are the main ecological factors that induce fish diseases besides pathogens. To maintain good water quality in the eel pond, the following points are generally required:

(1) Drug control. Every 10 to 15 days, use 10g/m3 of quicklime or 1g/m3 of bleaching powder to spray the whole pond. In the north, the water quality is alkaline, so bleaching powder should be used more often; in the south, the water quality is acidic, so quicklime can be used more often. Mix oxytetracycline, sulfonamides and other drugs into feed for oral administration. Each drug should be used for 3 to 5 days, and then used alternately every 20 to 30 days.

(2) Maintain a suitable water level. If the water level is too deep, the water temperature will drop, and the water quality will not be easy to improve. In addition, the eel needs to stick its head out of the water frequently to eat and breathe. To reduce the eel's physical consumption, the water level should be shallow. However, if the water level is too shallow, the water temperature will change dramatically, and the eel's activity space will be small, which is extremely unfavorable for the eel's growth and development. The general water level is 15-20 cm, and it can be deepened to 30 cm when the temperature is high. The water level may also change under special circumstances. For example, the water level in the seedling pond, the pond for sale, and the sick eel pond should be shallow, while the water level in the adult eel breeding pond can be deeper. If the aquatic plants grow luxuriantly, it is sufficient to change the water once a month. Generally, fresh water should be added in time according to the amount of water evaporation, but the leftover food on the feeding table should be cleaned every day to avoid deteriorating the water quality. When changing the water, the temperature difference between the inlet water and the water in the pond should be controlled. The temperature of small eels should not exceed 2°C, and that of large eels should not exceed 5°C. The daily temperature difference of the water temperature should be less than 10°C. It is best to build a reservoir to facilitate water changes.

(3) Maintain biodiversity. Eel ponds should be stocked with golden apple snails, field snails, small fish, loaches, etc. to remove residual bait and regulate water quality. Many organisms are also indicators of water quality. However, it is important to maintain a reasonable proportion of these organisms in terms of quantity. Generally, the food intake (dry weight) of yellow eels is 1% to 2% of their body weight, and the dry weight of fish feces is 2% to 10% of their food intake. Generally, the stocking density of eels does not exceed 3kg/m2. Calculated based on the dry food intake of loaches being 2% to 4% of their body weight, the number of loaches stocked per m2 of eel pond should not exceed 0.3kg. Loaches should be stocked after yellow eels have been tamed and fed with compound feed, so that they can fully play the role of eating yellow eel feces and preventing yellow eels from "fevering". Stocking toads is particularly effective in preventing the yellow eel's unique plum spot disease. Generally, 1 to 2 toads can be stocked in each small pond. The stocking density of snails should not exceed 0.25kg/m2. In addition, appropriate amount of green algae can be cultivated and photosynthetic bacteria (PSB) can be added.

Observing the water color is the key to regulating water quality. Generally, yellow-green, blue and clear water is good. Brown, gray or black water is abnormal and remedial measures should be taken in time.

IX. Diseases and prevention of eel farming

Disease prevention and treatment of eels The eels have relatively strong disease resistance and rarely get sick during artificial breeding. However, if they are poorly managed or the environmental factors are seriously adverse, their growth rate and survival rate may be affected.

1. Construction of cement pool

Choose a place with good lighting, warmth and ventilation, convenient transportation, sufficient water source, convenient water inlet and outlet, and no pollution source within 3 kilometers to build a pond.

2. Loach stocking

It is best to use wild loach seedlings caught in cages. There are two ways to grow loach seedlings: directly growing them in the same year and growing them in the next year. For growing loach seedlings directly in the same year, the loach seedlings with a body length of 3-5 cm are grown in June and harvested in June-August of the following year.

3. Feeding

Loaches have a mixed diet and can eat both natural and artificial baits. Artificial baits mainly include animal feeds such as maggots, earthworms, snails and clams, fish meal, silkworm pupae, pig blood, livestock and poultry waste, and plant feeds such as grains, wheat bran-based tung ears, rice bran, bean dregs, soy sauce residue, vegetable cakes, and cake dregs.

Nutritional value and efficacy of eel:

The eel has no scales, is yellow-brown in color, has irregular dark spots on the sides of its body, has underdeveloped and almost disappeared fins, has only one three-edged spine on its body, and is tender and delicious. The eel is rich in nutritional value, rich in protein, fat, calcium, phosphorus, iron, vitamins and a variety of phytochemicals, and is a good tonic. It is mainly used to treat deficiency of qi and blood, and weakness caused by chronic diarrhea and dysentery. The eel also has the effect of dredging meridians and benefiting joints, so patients with rheumatism can choose to eat it or soak it in wine.

Farming technology

1. Operation procedures of still water and soilless ecological breeding technology for yellow eel

There is a lot of content in the still water and soilless ecological breeding technology of rice field eels. The key technologies include shallow water semi-artificial breeding technology of rice field eels, compound feed domestication technology, and pest and disease control technology. Among them, eel species screening and processing are the key to the success or failure of rice field eel breeding.

2. Construction and treatment of eel ponds

The construction of eel ponds should take into account the following five design principles: simulate the natural environment; convenient drainage and irrigation, conducive to heat preservation; conducive to taming and feeding compound feed; conducive to the prevention and control of eel diseases and pests; escape prevention, easy capture and convenient management. The area of ​​outdoor static water soilless breeding ponds is 15-20m2, and the indoor breeding area is smaller, generally 6-10 m2. Pool wall height: 20-30cm indoors, 40-50cm outdoors. The wall can be built with a single brick, cement is applied inside, and the top of the wall is horizontally built with bricks in a "T" shape. Plastic film pools can also be used for breeding. Several small pools of the same specifications are strung together in a row, but the inlet and outlet are independent to prevent diseases and pests from spreading to each other. The shape of the fish pond is preferably rectangular or square. The outlet is slightly lower than the bottom of the pool to ensure thorough sewage discharge; the water inlet is set just above the food table, opposite to the outlet, and the position should be high, generally 15-20cm from the bottom of the pool; the overflow outlet is 25cm from the bottom of the pool, and the overflow outlet is not required for indoor breeding. The diameter of each water outlet is about 5-6cm and should be covered with a nylon net to facilitate the discharge of feces and prevent the eels from escaping.

After the cement pool is built, it must be de-alkali treated. Using a new pool without de-alkali treatment is one of the main reasons for the failure of many farmers. The method is: soak it with phosphate fertilizer (1 kg of phosphate fertilizer for 1 ton of water) or acetic acid for a week, drain the soaking water and replace it with clean water; or fill it with water and soak it for 30 days (it is best to put grass piles to ferment), and then drain it. Plastic film pools do not need to be de-alkali treated.

Fish nests are very important in static water and soilless culture. Various pipes, bamboo tubes, brick gaps, water plants, etc. can be used as fish nests. Since eels have a certain degree of aggregation, the area of ​​the fish nest should not be too small. The general principle of setting up eel nests is: it is convenient for eels to enter and exit freely, the interior is dark and lightless, and there is enough space. In production, it is generally better to use waste bicycle tires disinfected with potassium permanganate solution as eel nests. The tires are placed under the water plants, and 5-6 tires can be placed in each small pool. Bamboo tubes of about 2m can be used. The size of the hole depends on the eel body. It is appropriate to be larger than the eel. Every two bamboo tubes are in a row, and each pool has 3-5 rows, with a spacing of about 0.3m between each row. Bricks are placed under each row of bamboo nests to make a large space under the bamboo nests, which is convenient for water flow and sewage discharge. In order to fix the bamboo nests, it is best to press bricks above the hole, which also plays a role in shading and shading.

3. Aquatic Plant Stocking

"To raise fish, you must first raise water, and to raise water, you must first raise grass." The placement of aquatic plants is one of the key technologies for static water soilless aquaculture. Reasonable placement of aquatic plants to purify water quality can reduce the number of water changes in the eel pond to once a month, saving water and labor, and can prevent heatstroke, reduce stress reactions, provide fish nests, and prevent diseases and insect pests. Aquatic plants are selected according to the standards of "preventing fish from escaping, growing fast, purifying water quality, and facilitating fish hiding." Common ones include water peanuts, water hyacinths, water lilies, and fine green duckweed. The planting area of ​​aquatic plants should not exceed 2/3 of the total pond area. At least 1/3 of the fish pond area should be left empty to set up a feeding table and facilitate the activities of yellow eels. In different seasons, aquatic plants should be reasonably matched in a certain proportion. In summer, water hyacinths and water lilies are the main ones, while in spring and autumn, water peanuts and fine green duckweed are the main ones. In winter, no aquatic plants are left to prevent yellow eels from freezing under the aquatic plants. Generally, aquatic plants are put in 15 days before stocking eels. Before putting in, they should be disinfected by soaking in 100g/m3 potassium permanganate solution for 0.5h, or by soaking in 10g/m3 copper sulfate solution for insecticide.

In daily management, excess aquatic plants should be removed in time or overly long aquatic plants should be cut. In combination with eel pond disinfection, 10g/m3 quicklime or 0.7g/m3 copper sulfate solution should be sprinkled on the grass to prevent aquatic plant pathogen infection.

4. Eel species selection

The key to successful eel farming is the quality of seedlings. At present, the large-scale breeding technology of eels has not yet been mastered, and the seedlings used in production are basically from wild resources. There are many ways to catch wild eels, including cage catching, hook fishing, electric shock, shovel digging, clamp catching, net lifting and drug catching. Some wild eels have been transferred and stored and transported many times, and some wild eels themselves carry diseases and insect pests. Therefore, the quality of wild eel seedlings purchased from the market is uneven, and strict screening is very important in production.

There are many methods for screening eel seedlings. The sensory screening method (based on body color, external injuries, strength, mucus, etc.), water flow screening method, behavioral screening method, and burrowing screening method are highly subjective and cannot screen eels with latent diseases in the body. It is also rather troublesome to screen them one by one. The drug immersion method is highly irritating to eels, the drug concentration is difficult to control, and the operation is rather troublesome. The feeding screening method has a better screening effect, but there are no reports on its specific operation process and quantitative method.

The eel selection method we use in production is: put the eel seedlings in a plastic container in shallow water at a certain density, soak them in medicine, feed them a fixed amount of empty mealworm larvae for 5 consecutive days, change the water once every morning, and check the eel's food intake. In the range of 18-30℃, if the average daily food intake of the eel exceeds 0.5% of the eel's body weight, then keep the seedlings; if the average daily food intake of the eel is less than 0.5% of the eel's body weight, then eliminate the seedlings. The eel stocking time is generally 10-15 days after the water plants are released.

5. Semi-artificial breeding technology of yellow eel

The semi-artificial breeding technology of the yellow eel has the advantages of high fertilization rate and hatching rate, concentrated breeding time, convenient management and high efficiency, and is an inevitable trend for the large-scale breeding of yellow eels. The breeding pond is designed and built according to the requirements of static water soilless breeding, with an area of ​​20-30m2. The types of aquatic plants vary from place to place, including water hyacinth (Eichhornia Crassipes Solm.), water peanut (Alternanthera Philoxeroides Griseb), water lily (Pistia stratiotes), and goldfish algae (Ceratophyllum demersum). From March to July each year, 10 parent eels are stocked per square meter of the breeding pond (female: male ratio is 6:4). The management method is the same as static water soilless ecological breeding, but the number of water changes is increased during the breeding season (May to August), that is, the water is changed once every 7 days, the water depth is 20-25cm, and the pH is 6.0-8.5. After the yellow eel lays eggs, it is promptly fished out for artificial incubation, and the unfertilized eggs should be removed in time. The drip incubation method is: the incubator is a shallow dish of 40cm×40cm×7cm, with 2cm thick sterilized river sand on the bottom, water drips in from a high container and overflows from the side wall of the dish, the water depth is kept at about 5cm, and the daily temperature difference does not exceed 2℃. When the fertilized eggs just enter the incubator, the water dripping frequency is 10 drops/min, which lasts for 24 hours, and then the water dripping speed is gradually increased until the seedlings are hatched.

6. Eel Taming

Rice field eels are very selective about food, and once they adapt to a certain food, it is difficult for them to change their eating habits. At present, the artificially cultured eels mainly come from wild eels that eat live bait. If they are fed with live bait alone, it is not conducive to the healthy growth of rice field eels, and it increases the input cost, and may be limited by the fact that feed resources cannot be available for a long time. If they are fed with compound feed or a small amount of live bait is mixed into compound feed, it is possible to effectively reduce feed costs, ensure comprehensive nutrition, facilitate the addition of additives and drugs, and prevent and control diseases and insect pests. Therefore, feeding compound feed is an important measure to develop the rice field eel farming industry.

1. Taming conditions

(1) The feeder must be patient. The feeding process takes at least 7-10 days. It is normal to succeed in feeding in 10-30 days.

(2) The eel pond should be small, generally 15-20m2. The eel feeds by using its sense of smell, taste and lateral line system in an integrated manner. The eel must be within an effective range to find and prey on food.

(3) Feeding training must be based on the four principles of “fixed location, fixed time, fixed quality and fixed quantity” that the eel can eat.

(4) Feeding should be done according to the season, weather and the size of the eel species. For example, it is very suitable for feeding eels when they just finish hibernation, the temperature rises and they start to feed.

(5) If it is a wild eel, the leeches should be carefully screened and killed, and the eel should be domesticated and eaten after being stabilized for a period of time.

(6) It is not advisable to release loaches or other fish into the water before taming the eels. Releasing them too early will cause them to compete with the eels for food, which will be detrimental to taming the eels.

2. Food Taming Method

Taking advantage of the eel's swallowing and greedy nature, live bait is mixed with compound feed for feeding training. The eel's start feeding time, peak feeding time and finishing time are required to be mastered to facilitate artificial feeding training.

(1) Before training, the eels must be starved for 1-2 days without being fed any food.

(2) Before starting to train the eels, feed them with live bait that accounts for about 1% of their weight for 2-3 days, such as river frogs, earthworms, mealworms, etc., and the "four determinations" must be achieved.

(3) After stopping feeding for another 1-2 days, make the compound feed and live bait into a "cake" style, that is, cut part of the live bait into pieces and mix it with the compound feed, and stick part of it to the outside, or use a dough press to press it into thin strips for feeding. The total amount is about 1% of the weight of the stocked eels. On the first day, it is 80% live bait and 20% compound feed, on the 2nd-3rd day, it is 60% live bait and 40% compound feed, on the 4th-5th day, it is 40% live bait and 60% compound feed, and so on. Generally, it will take 7-10 days for the eels to be fully tamed and eat artificial compound feed.

(4) During the feeding process, observe the leftover food, water quality and excrement every day to judge the feeding situation of the eel. If the feeding is abnormal, remove the leftover bait and reduce the proportion of compound feed or appropriately reduce the feeding amount. If the eel still cannot eat normally, stop feeding for 1-2 days and then continue. If the eel can finish eating, gradually increase the proportion of compound feed until the feeding is successfully trained. After the feeding is successfully trained, immediately mix drugs into the compound feed to kill parasites. For the eels that have been successfully trained, make the compound feed into dry granules the size of mung beans or peas and feed them. The total amount should also be gradually increased to 2%-10% of the eel weight, and then enter the daily management work.

7. Summer Shade

The still water soilless breeding pond for yellow eel is small (15-20m2), with shallow water level (about 15-20cm), and the water temperature can easily exceed 30℃ in summer. Shading is an essential step to avoid the heat. Generally, a shade net is set up on the pond, and climbing plants such as grapes, loofah, trichosanthes, and pumpkins are planted by the pond. But pay attention to leaving 10% to 30% of light on the surface of the pond. At the same time, when the temperature exceeds 33℃, the water level in the pond should be deepened to reduce the density of yellow eels, and new water should be slowly injected. Groundwater can be used to adjust the water temperature of the eel pond.

8. Water quality control

The pH value, transparency, dissolved oxygen, ammonia nitrogen, temperature, nitrite and sulfide of the aquaculture water are the main ecological factors that induce fish diseases besides pathogens. To maintain good water quality in the eel pond, the following points are generally required:

(1) Drug control. Every 10 to 15 days, use 10g/m3 of quicklime or 1g/m3 of bleaching powder to spray the whole pond. In the north, the water quality is alkaline, so bleaching powder should be used more often; in the south, the water quality is acidic, so quicklime can be used more often. Mix oxytetracycline, sulfonamides and other drugs into feed for oral administration. Each drug should be used for 3 to 5 days, and then used alternately every 20 to 30 days.

(2) Maintain a suitable water level. If the water level is too deep, the water temperature will drop, and the water quality will not be easy to improve. In addition, the eel needs to stick its head out of the water frequently to eat and breathe. To reduce the eel's physical consumption, the water level should be shallow. However, if the water level is too shallow, the water temperature will change dramatically, and the eel's activity space will be small, which is extremely unfavorable for the eel's growth and development. The general water level is 15-20 cm, and it can be deepened to 30 cm when the temperature is high. The water level may also change under special circumstances. For example, the water level in the seedling pond, the pond for sale, and the sick eel pond should be shallow, while the water level in the adult eel breeding pond can be deeper. If the aquatic plants grow luxuriantly, it is sufficient to change the water once a month. Generally, fresh water should be added in time according to the amount of water evaporation, but the leftover food on the feeding table should be cleaned every day to avoid deteriorating the water quality. When changing the water, the temperature difference between the inlet water and the water in the pond should be controlled. The temperature of small eels should not exceed 2°C, and that of large eels should not exceed 5°C. The daily temperature difference of the water temperature should be less than 10°C. It is best to build a reservoir to facilitate water changes.

(3) Maintain biodiversity. Eel ponds should be stocked with golden apple snails, field snails, small fish, loaches, etc. to remove residual bait and regulate water quality. Many organisms are also indicators of water quality. However, it is important to maintain a reasonable proportion of these organisms in terms of quantity. Generally, the food intake (dry weight) of yellow eels is 1% to 2% of their body weight, and the dry weight of fish feces is 2% to 10% of their food intake. Generally, the stocking density of eels does not exceed 3kg/m2. Calculated based on the dry food intake of loaches being 2% to 4% of their body weight, the number of loaches stocked per m2 of eel pond should not exceed 0.3kg. Loaches should be stocked after yellow eels have been tamed and fed with compound feed, so that they can fully play the role of eating yellow eel feces and preventing yellow eels from "fevering". Stocking toads is particularly effective in preventing the yellow eel's unique plum spot disease. Generally, 1 to 2 toads can be stocked in each small pond. The stocking density of snails should not exceed 0.25kg/m2. In addition, appropriate amount of green algae can be cultivated and photosynthetic bacteria (PSB) can be added.

Observing the water color is the key to regulating water quality. Generally, yellow-green, blue and clear water is good. Brown, gray or black water is abnormal and remedial measures should be taken in time.

IX. Diseases and prevention of eel farming

Disease prevention and treatment of eels The eels have relatively strong disease resistance and rarely get sick during artificial breeding. However, if they are poorly managed or the environmental factors are seriously adverse, their growth rate and survival rate may be affected.

Farming technology

1. Operation procedures of still water and soilless ecological breeding technology for yellow eel

The content of the still water and soilless ecological breeding technology of rice field eels is quite extensive. The key technologies include the shallow water semi-artificial breeding technology of rice field eels, the rapid domestication technology with compound feed, and the disease and pest control technology. Among them, the screening and processing of eel species are the key to the success of rice field eel breeding.

2. Construction and treatment of eel ponds

The construction of eel ponds should take into account the following five design principles: simulate the natural environment; convenient drainage and irrigation, conducive to heat preservation; conducive to taming and feeding compound feed; conducive to the prevention and control of eel diseases and pests; escape prevention, easy capture and convenient management. The area of ​​outdoor static water soilless breeding ponds is 15-20m2, and the indoor breeding area is smaller, generally 6-10 m2. Pool wall height: 20-30cm indoors, 40-50cm outdoors. The wall can be built with a single brick, cement is applied inside, and the top of the wall is horizontally built with bricks in a "T" shape. Plastic film pools can also be used for breeding. Several small pools of the same specifications are strung together in a row, but the inlet and outlet are independent to prevent diseases and pests from spreading to each other. The shape of the fish pond is preferably rectangular or square. The outlet is slightly lower than the bottom of the pool to ensure thorough sewage discharge; the water inlet is set just above the food table, opposite to the outlet, and the position should be high, generally 15-20cm from the bottom of the pool; the overflow outlet is 25cm from the bottom of the pool, and the overflow outlet is not required for indoor breeding. The diameter of each water outlet is about 5-6cm and should be covered with a nylon net to facilitate the discharge of feces and prevent the eels from escaping.

After the cement pool is built, it must be de-alkali treated. Using a new pool without de-alkali treatment is one of the main reasons for the failure of many farmers. The method is: soak it with phosphate fertilizer (1 kg of phosphate fertilizer for 1 ton of water) or acetic acid for a week, drain the soaking water and replace it with clean water; or fill it with water and soak it for 30 days (it is best to put grass piles to ferment), and then drain it. Plastic film pools do not need to be de-alkali treated.

Fish nests are very important in static water and soilless culture. Various pipes, bamboo tubes, brick gaps, water plants, etc. can be used as fish nests. Since eels have a certain degree of aggregation, the area of ​​the fish nest should not be too small. The general principle of setting up eel nests is: it is convenient for eels to enter and exit freely, the interior is dark and lightless, and there is enough space. In production, it is generally better to use waste bicycle tires disinfected with potassium permanganate solution as eel nests. The tires are placed under the water plants, and 5-6 tires can be placed in each small pool. Bamboo tubes of about 2m can be used. The size of the hole depends on the eel body. It is appropriate to be larger than the eel. Every two bamboo tubes are in a row, and each pool has 3-5 rows, with a spacing of about 0.3m between each row. Bricks are placed under each row of bamboo nests to make a large space under the bamboo nests, which is convenient for water flow and sewage discharge. In order to fix the bamboo nests, it is best to press bricks above the hole, which also plays a role in shading and shading.

3. Aquatic Plant Stocking

"To raise fish, you must first raise water, and to raise water, you must first raise grass." The placement of aquatic plants is one of the key technologies for static water soilless aquaculture. Reasonable placement of aquatic plants to purify water quality can reduce the number of water changes in the eel pond to once a month, saving water and labor, and can prevent heatstroke, reduce stress reactions, provide fish nests, and prevent diseases and insect pests. Aquatic plants are selected according to the standards of "preventing fish from escaping, growing fast, purifying water quality, and facilitating fish hiding." Common ones include water peanuts, water hyacinths, water lilies, and fine green duckweed. The planting area of ​​aquatic plants should not exceed 2/3 of the total pond area. At least 1/3 of the fish pond area should be left empty to set up a feeding table and facilitate the activities of yellow eels. In different seasons, aquatic plants should be reasonably matched in a certain proportion. In summer, water hyacinths and water lilies are the main ones, while in spring and autumn, water peanuts and fine green duckweed are the main ones. In winter, no aquatic plants are left to prevent yellow eels from freezing under the aquatic plants. Generally, aquatic plants are put in 15 days before stocking eels. Before putting in, they should be disinfected by soaking in 100g/m3 potassium permanganate solution for 0.5h, or by soaking in 10g/m3 copper sulfate solution for insecticide.

In daily management, excess aquatic plants should be removed in time or overly long aquatic plants should be cut. In combination with eel pond disinfection, 10g/m3 quicklime or 0.7g/m3 copper sulfate solution should be sprinkled on the grass to prevent aquatic plant pathogen infection.

4. Eel species selection

The key to successful eel farming is the quality of seedlings. At present, the large-scale breeding technology of eels has not yet been mastered, and the seedlings used in production are basically from wild resources. There are many ways to catch wild eels, including cage catching, hook fishing, electric shock, shovel digging, clamp catching, net lifting and drug catching. Some wild eels have been transferred and stored and transported many times, and some wild eels themselves carry diseases and insect pests. Therefore, the quality of wild eel seedlings purchased from the market is uneven, and strict screening is very important in production.

There are many methods for screening eel seedlings. The sensory screening method (based on body color, external injuries, strength, mucus, etc.), water flow screening method, behavioral screening method, and burrowing screening method are highly subjective and cannot screen eels with latent diseases in the body. It is also troublesome to screen them one by one. The drug immersion method is highly irritating to eels, the drug concentration is difficult to control, and the operation is also troublesome. The feeding screening method has a better screening effect, but there are no reports on its specific operation process and quantitative method.

The eel selection method we use in production is: put the eel seedlings in a shallow plastic container at a certain density, soak them in medicine, feed them a fixed amount of empty mealworm larvae for 5 consecutive days, change the water once every morning, and check the eel's food intake. In the range of 18-30℃, if the average daily food intake of the eel exceeds 0.5% of the eel's body weight, then keep the seedlings; if the average daily food intake of the eel is less than 0.5% of the eel's body weight, then eliminate the seedlings. The eel stocking time is generally 10-15 days after the water plants are put in.

5. Semi-artificial breeding technology of yellow eel

The semi-artificial breeding technology of the yellow eel has the advantages of high fertilization rate and hatching rate, concentrated breeding time, convenient management and high efficiency, and is an inevitable trend for the large-scale breeding of yellow eels. The breeding pond is designed and built according to the requirements of static water soilless breeding, with an area of ​​20-30m2. The types of aquatic plants vary from place to place, including water hyacinth (Eichhornia Crassipes Solm.), water peanut (Alternanthera Philoxeroides Griseb), water lily (Pistia stratiotes), and goldfish algae (Ceratophyllum demersum). From March to July each year, 10 parent eels are stocked per square meter of the breeding pond (female: male ratio is 6:4). The management method is the same as static water soilless ecological breeding, but the number of water changes is increased during the breeding season (May to August), that is, the water is changed once every 7 days, the water depth is 20-25cm, and the pH is 6.0-8.5. After the yellow eel lays eggs, it is promptly fished out for artificial incubation, and the unfertilized eggs should be removed in time. The drip incubation method is: the incubator is a shallow dish of 40cm×40cm×7cm, with 2cm thick sterilized river sand on the bottom, water drips in from a high container and overflows from the side wall of the dish, the water depth is kept at about 5cm, and the daily temperature difference does not exceed 2℃. When the fertilized eggs just enter the incubator, the water dripping frequency is 10 drops/min, which lasts for 24 hours, and then the water dripping speed is gradually increased until the seedlings are hatched.

6. Eel Taming

Rice field eels are very selective about food, and once they adapt to a certain food, it is difficult for them to change their eating habits. At present, the artificially cultured eels mainly come from wild eels that eat live bait. If they are fed with live bait alone, it is not conducive to the healthy growth of rice field eels, and it increases the input cost, and may be limited by the fact that feed resources cannot be available for a long time. If they are fed with compound feed or a small amount of live bait is mixed into compound feed, it is possible to effectively reduce feed costs, ensure comprehensive nutrition, facilitate the addition of additives and drugs, and prevent and control diseases and insect pests. Therefore, feeding compound feed is an important measure to develop the rice field eel farming industry.

1. Taming conditions

(1) The feeder must be patient. The feeding process takes at least 7-10 days. It is normal to succeed in feeding in 10-30 days.

(2) The eel pond should be small, generally 15-20m2. The eel feeds by using its sense of smell, taste and lateral line system in an integrated manner. The eel must be within an effective range to find and prey on food.

(3) Feeding training must be based on the four principles of “fixed location, fixed time, fixed quality and fixed quantity” that the eel can eat.

(4) Feeding should be done according to the season, weather and the size of the eel species. For example, it is very suitable for feeding eels when they just finish hibernation, the temperature rises and they start to feed.

(5) If it is a wild eel, the leeches should be carefully screened and killed, and the eel should be domesticated and eaten after being stabilized for a period of time.

(6) It is not advisable to release loaches or other fish into the water before taming the eels. Releasing them too early will cause them to compete with the eels for food, which will be detrimental to taming the eels.

2. Food Taming Method

Taking advantage of the eel's swallowing and greedy nature, live bait is mixed with compound feed for feeding training. The eel's start feeding time, peak feeding time and finishing time are required to be mastered to facilitate artificial feeding training.

(1) Before training, the eels must be starved for 1-2 days without being fed any food.

(2) Before starting to train the eels, feed them with live bait that accounts for about 1% of their weight for 2-3 days, such as river frogs, earthworms, mealworms, etc., and the "four determinations" must be achieved.

(3) After stopping feeding for another 1-2 days, make the compound feed and live bait into a "cake" style, that is, cut part of the live bait into pieces and mix it with the compound feed, and stick part of it to the outside, or use a dough press to press it into thin strips for feeding. The total amount is about 1% of the weight of the stocked eels. On the first day, it is 80% live bait and 20% compound feed, on the 2nd-3rd day, it is 60% live bait and 40% compound feed, on the 4th-5th day, it is 40% live bait and 60% compound feed, and so on. Generally, it will take 7-10 days for the eels to be fully tamed and eat artificial compound feed.

(4) During the feeding process, observe the leftover food, water quality and excrement every day to judge the feeding situation of the eel. If the feeding is abnormal, remove the leftover bait and reduce the proportion of compound feed or appropriately reduce the feeding amount. If the eel still cannot eat normally, stop feeding for 1-2 days and then continue. If the eel can finish eating, gradually increase the proportion of compound feed until the feeding is successfully trained. After the feeding is successfully trained, immediately mix drugs into the compound feed to kill parasites. For the eels that have been successfully trained, make the compound feed into dry granules the size of mung beans or peas and feed them. The total amount should also be gradually increased to 2%-10% of the eel weight, and then enter the daily management work.

7. Summer Shade

The still water soilless breeding pond for yellow eel is small (15-20m2), with shallow water level (about 15-20cm), and the water temperature can easily exceed 30℃ in summer. Shading is an essential step to avoid the heat. Generally, a shade net is set up on the pond, and climbing plants such as grapes, loofah, trichosanthes, and pumpkins are planted by the pond. But pay attention to leaving 10% to 30% of light on the surface of the pond. At the same time, when the temperature exceeds 33℃, the water level in the pond should be deepened to reduce the density of yellow eels, and new water should be slowly injected. Groundwater can be used to adjust the water temperature of the eel pond.

8. Water quality control

The pH value, transparency, dissolved oxygen, ammonia nitrogen, temperature, nitrite and sulfide of the aquaculture water are the main ecological factors that induce fish diseases besides pathogens. To maintain good water quality in the eel pond, the following points are generally required:

(1) Drug control. Every 10 to 15 days, use 10g/m3 of quicklime or 1g/m3 of bleaching powder to spray the whole pond. In the north, the water quality is alkaline, so bleaching powder should be used more often; in the south, the water quality is acidic, so quicklime can be used more often. Mix oxytetracycline, sulfonamides and other drugs into feed for oral administration. Each drug should be used for 3 to 5 days, and then used alternately every 20 to 30 days.

(2) Maintain a suitable water level. If the water level is too deep, the water temperature will drop, and the water quality will not be easy to improve. In addition, the eel needs to stick its head out of the water frequently to eat and breathe. To reduce the eel's physical consumption, the water level should be shallow. However, if the water level is too shallow, the water temperature will change dramatically, and the eel's activity space will be small, which is extremely unfavorable for the eel's growth and development. The general water level is 15-20 cm, and it can be deepened to 30 cm when the temperature is high. The water level may also change under special circumstances. For example, the water level in the seedling pond, the pond for sale, and the sick eel pond should be shallow, while the water level in the adult eel breeding pond can be deeper. If the aquatic plants grow luxuriantly, it is sufficient to change the water once a month. Generally, fresh water should be added in time according to the amount of water evaporation, but the leftover food on the feeding table should be cleaned every day to avoid deteriorating the water quality. When changing the water, the temperature difference between the inlet water and the water in the pond should be controlled. The temperature of small eels should not exceed 2°C, and that of large eels should not exceed 5°C. The daily temperature difference of the water temperature should be less than 10°C. It is best to build a reservoir to facilitate water changes.

(3) Maintain biodiversity. Eel ponds should be stocked with golden apple snails, field snails, small fish, loaches, etc. to remove residual bait and regulate water quality. Many organisms are also indicators of water quality. However, it is important to maintain a reasonable proportion of these organisms in terms of quantity. Generally, the food intake (dry weight) of yellow eels is 1% to 2% of their body weight, and the dry weight of fish feces is 2% to 10% of their food intake. Generally, the stocking density of eels does not exceed 3kg/m2. Calculated based on the dry food intake of loaches being 2% to 4% of their body weight, the number of loaches stocked per m2 of eel pond should not exceed 0.3kg. Loaches should be stocked after yellow eels have been tamed and fed with compound feed, so that they can fully play the role of eating yellow eel feces and preventing yellow eels from "fevering". Stocking toads is particularly effective in preventing the yellow eel's unique plum spot disease. Generally, 1 to 2 toads can be stocked in each small pond. The stocking density of snails should not exceed 0.25kg/m2. In addition, appropriate amount of green algae can be cultivated and photosynthetic bacteria (PSB) can be added.

Observing the water color is the key to regulating water quality. Generally, yellow-green, blue and clear water is good. Brown, gray or black water is abnormal and remedial measures should be taken in time.

IX. Diseases and prevention of eel farming

Disease prevention and treatment of eels The eels have relatively strong disease resistance and rarely get sick during artificial breeding. However, if they are poorly managed or the environmental factors are seriously adverse, their growth rate and survival rate may be affected.