Detailed Explanation of Essential Techniques for Spring Rice Field Eel Farming
Essential Techniques for Spring Rice Field Eel Farming
The rice field eel farming method is simple, with abundant feed sources, low cost, and quick results; rural households can all carry out farming according to local conditions. Today we introduce to farmer friends the technical key points, precautions, and latest methods of rice field eel farming. In spring, the incidence of disease in rice field eels is relatively high, and the vast number of farmers farming rice field eels must raise them scientifically.
Eel Fry Breeding
For selecting new fish as broodstock for breeding, female eels should be chosen with a body length of 35 cm or more, weighing 50-150 g, with a swollen abdomen showing a transparent band, and a red and swollen genital pore; those with egg grains are best. Male eels should be chosen with a length of 55 cm or more, weighing over 150 g, with blood-streaked markings on the ventral surface, able to excrete a transparent fluid when the abdomen is squeezed, and with sperm visible under microscopic examination. It is advisable to pair 2-3 female eels with 1 male eel.
For induced spawning and reproduction, measures such as aeration, increasing water exchange, adjusting stocking density, and providing high-quality bait can be adopted to naturally induce spawning in broodstock eels and improve their reproductive capacity. Alternatively, a one-time injection of lrh-a can be given: female eels receive 10 micrograms per 50 g of body weight, and male eels receive 15-25 mg per fish; male eels should be injected 24 hours earlier than female eels via coelomic injection. During injection, the depth should not exceed 0.5 cm, and the injection volume should not exceed 1 ml, for the best induced spawning effect.
For artificial insemination, hold the front part of the female eel with one hand using a towel, and squeeze the abdomen backward with the other hand. If the cloaca is blocked, it can be cut open before squeezing out the eggs; place the squeezed eggs into a disinfected jar or basin. Kill the selected male eel, cut the testis into pieces and grind them fine, wrap the minced testis in a 100-mesh sieve, squeeze the semen into the container holding the eggs, stir thoroughly for 5 minutes, wash away testis remnants and blood with clean water, and place the fertilized eggs into a temperature-controlled incubator or indoors for incubation. Regardless of the number of eggs, at least 2 or more male eels should be used for fertilization.
For temperature-controlled incubation, the water depth should preferably be about 10 cm. Water should be changed frequently during the process, but the temperature difference must not exceed 4°C. The higher the water temperature, the shorter the time required for incubation.
For fry cultivation, cement ponds are preferable. A small amount of manure fertilizer water should be applied appropriately in the pond for tubifex reproduction, and aquatic plants such as water hyacinth should be grown on the water surface. The fry stocking density is about 200 per sq m. After 1-2 months, when the eel fry grow to about 10 cm, they can be moved to adult eel ponds for rearing.
Disease Prevention and Control
8-10 days before stocking rice field eels, use quicklime at 100 g/sq m to disinfect the pond. During the farming process, every 30 days insert a pipe into the pond bottom to infuse a 20 ppm calcium peroxide solution to increase oxygen at the pond bottom, preventing the bottom silt from rotting due to lack of oxygen and causing disease in the rice field eels. Every 15 days, splash the entire pond with 15 mmp quicklime for disinfection. In addition, every 5 days, use 20 g of allicin per 100 kg of rice field eels, feeding once daily for 3 consecutive days, to prevent disease. Common diseases of rice field eels include:
Tail rot disease: In the early stage, the tail of the rice field eel becomes congested and inflamed, the muscles undergo necrosis and ulceration, and reactions become sluggish. In severe cases, the tail rots off, and the eel eventually loses mobility and dies. Prevention and treatment methods: prevent injury to seed stock during transport, avoid excessive stocking density, pay attention to frequently changing clean water sources, and splash the entire pond with eel disease remedy.
Skin rot disease: In the early stage, red spots of varying sizes appear on the body surface of the rice field eel, with pinpoint congestion and inflammation, especially obvious on both sides of the abdomen, and weak swimming. When the condition is severe, the epidermis of the diseased eel ulcerates in pinpoint patches, with irregular small holes on the body surface, and infection of internal organs leads to death. Prevention and treatment methods: thoroughly clean the pond with quicklime to eliminate pathogens and prevent contamination. In spring, splash the entire pond with 5-10 ml of eel disease remedy per cubic meter of water, using 3 consecutive days as one treatment course.
Cold: Pay attention to ensuring the temperature difference is not too large when changing water, which can prevent the occurrence of this disease.
Enteritis disease: Diseased eels show reduced appetite, slow swimming, darkened body color, swollen abdomen, and red and swollen anus. Local or entire intestinal congestion and inflammation occur. Prevention and treatment methods: strengthen feeding management, do not feed rotten bait. Soak and wash with 1-2 g of bleaching powder or 10 g of quicklime per cubic meter of water for 5 minutes, and feed with eel stop medicine mixed into the feed for 3 consecutive days.
Capillariasis: Parasitizes inside the eel body, causing the fish to become emaciated and die, accompanied by edema and red and swollen anus. Use 0.1 g of 90% crystalline trichlorfon per kg of rice field eel, mix into the feed and feed for 6 consecutive days.
Artificial Fattening
Pond construction: Rice field eel farming ponds should be built in wind-sheltered, sunny places with guaranteed water sources and relatively solid soil. Cement ponds, earthen ponds, and rice field farming are all acceptable. The pond area for farming rice field eels depends on the scale of farming, generally 20-100 sq m is suitable, with a pond depth of 70 cm. The pond wall should be about 30 cm above the water surface to prevent the rice field eels from escaping. The pond shape is best as a long oval. The pond perimeter should be built with bricks, and the top of the pond side wall should be made into a "t" shape with an overhang of about 20 cm. The pond bottom should be paved with cement, and then about 25 cm of pond mud should be spread on top to facilitate the rice field eels burrowing and hiding. The cement in the pond should not be too deep, preferably maintained at about 15 cm. Drainage holes should be equipped with low-lying anti-escape ponds and old nylon nets. One-third of the pond water surface area should be planted with aquatic plants such as water hyacinth, serving as shade and hiding habitat for the rice field eels.
For eel stocking, the seed stock should preferably come from artificially bred and domesticated excellent dark yellow large-spotted rice field eels. The eel fry should mainly be wild, selecting seed stock with no body damage, no parasites, strong physique, and uniform size, 60-80 fish per kg, stocking about 1 kg of rice field eel fry per sq m. For eel fry of 20-30 fish/kg, the stocking density is 3-4 kg/sq m; for eel fry of 10-20 fish/kg, the stocking density is 4-6 kg/sq m. Eel fry of different sizes should be raised in separate ponds, and at the same time, a small amount of loach should be added at a ratio of 10%.
Feeding management 1. Feed feeding: Rice field eel feed can be earthworms, river mussel meat, snail meat, small miscellaneous fish, small tadpoles, small insects, animal viscera, and fruits and vegetables. Rice field eels hide by day and come out at night. Within one week after stocking, generally feed after dark in the afternoon, then gradually advance the feeding time, training them until they can be fed at 2 PM at the earliest; the feeding rate for fresh bait is 5%-6%, and the feeding rate for dry bait is 1%-2%, with adjustments based on water temperature. The animal-based bait to be fed must be fresh. 2. Daily management: mainly maintain the water quality as "fertile, lively, tender, and refreshing." When just stocking, the pond water should be shallower, preferably 10 cm, then gradually deepen the water level, generally maintained at 15-20 cm. Water should be changed frequently, once every 3 days, with 1/2 of the water changed each time. In summer during high temperatures, change water once daily, preferably in the early morning, when the temperature of the water source is basically consistent with the pond water temperature, preventing the rice field eels from catching "cold" due to too large a temperature difference (greater than 3 degrees). Every morning, promptly remove dead eels, diseased eels, and weak eels. Vine plants such as loofah and grapes can be planted along the pond edge for shade and cooling.
Three Farming Methods
Rice Field Eel Cage Farming
Cage farming is suitable for large water bodies. The main advantage is that water flows through the mesh, creating a flowing water environment inside the cage, resulting in fresh water quality and rich dissolved oxygen, allowing for high-density intensive farming. The main farming techniques are as follows:
The cage area is best at about 20 sq m, with a net length of 5 m, width of 4 m, and height of 1 m, with the above-water part being 40 cm and the underwater part being 60 cm. The net quality should be good, the mesh should be dense, and the net strips should be tight. The cages should be set in ponds with a water depth of 0.8 m or more. The cages can be arranged side by side in the pond, with bamboo racks built between the two rows of cages for walking and feeding management. The cage installation area should not exceed 50% of the total pond area, otherwise it easily causes water quality deterioration. Aquatic plants should be placed in the cages, preferably water peanut, with a coverage area of 90-95% of the cage area.
Rice Field Eel Plastic Greenhouse Soilless Flowing Water Farming
Using plastic greenhouses to farm rice field eels allows continuous production throughout the year. Soilless flowing water farming can effectively control diseases and multiply benefits. Plastic greenhouse soilless flowing water farming mainly has the following two methods:
(1) Open type. Suitable for building ponds in places with warm flowing water year-round, suitable for larger-scale operations. The rearing ponds are built with bricks and cement, each pond with an area of 10-20 sq m, pond depth of 40 cm, width of 1-2 m, and pond ridge width of 20-40 cm. At opposite positions in the pond, install 2 inlet pipes and 2 drainage pipes each with a diameter of 3-4 cm. (2) Closed recirculating filtration type. Suitable for use in large cities or places lacking water sources. The rearing water can be reused, with relatively low water consumption and easy temperature control, but the investment is slightly larger. In addition, aeration ponds and sedimentation ponds need to be built, along with some water purification equipment, pumping equipment, and heating equipment.
Rice Field Eel Rice Field Farming
Using rice fields to farm rice field eels has low cost and is convenient to manage. It produces both rice grain and fish, and is an effective way for farmers to increase income. Selection and requirements of rice fields: Rice fields for farming rice field eels should be selected with good water retention, low-lying terrain, and convenient irrigation and drainage. First, raise and reinforce the field ridges to achieve no seepage or leakage. Second, dig a set of surrounding trenches inside and outside the field perimeter, with a width of 5 m and depth of 1 m. In addition, dig "+" or "well"-shaped small trenches in the middle of the field, with a width of 50 cm and depth of 30 cm, connected to the surrounding trenches. Third, establish a good irrigation and drainage system, and install sturdy fish-blocking facilities at the inlet and outlet to prevent fish from escaping. The seed stocking time is concentrated in mid-to-late April with a one-time full stocking. When stocking fingerlings, soak and wash them in 3%-4% salt water for 10 minutes to prevent epidermal abrasions and kill water mold and external parasites.
Eel Fry Breeding
For selecting new fish as broodstock for breeding, female eels should be chosen with a body length of 35 cm or more, weighing 50-150 g, with a swollen abdomen showing a transparent band, and a red and swollen genital pore; those with egg grains are best. Male eels should be chosen with a length of 55 cm or more, weighing over 150 g, with blood-streaked markings on the ventral surface, able to excrete a transparent fluid when the abdomen is squeezed, and with sperm visible under microscopic examination. It is advisable to pair 2-3 female eels with 1 male eel.
For induced spawning and reproduction, measures such as aeration, increasing water exchange, adjusting stocking density, and providing high-quality bait can be adopted to naturally induce spawning in broodstock eels and improve their reproductive capacity. Alternatively, a one-time injection of lrh-a can be given: female eels receive 10 micrograms per 50 g of body weight, and male eels receive 15-25 mg per fish; male eels should be injected 24 hours earlier than female eels via coelomic injection. During injection, the depth should not exceed 0.5 cm, and the injection volume should not exceed 1 ml, for the best induced spawning effect.
For artificial insemination, hold the front part of the female eel with one hand using a towel, and squeeze the abdomen backward with the other hand. If the cloaca is blocked, it can be cut open before squeezing out the eggs; place the squeezed eggs into a disinfected jar or basin. Kill the selected male eel, cut the testis into pieces and grind them fine, wrap the minced testis in a 100-mesh sieve, squeeze the semen into the container holding the eggs, stir thoroughly for 5 minutes, wash away testis remnants and blood with clean water, and place the fertilized eggs into a temperature-controlled incubator or indoors for incubation. Regardless of the number of eggs, at least 2 or more male eels should be used for fertilization.
For temperature-controlled incubation, the water depth should preferably be about 10 cm. Water should be changed frequently during the process, but the temperature difference must not exceed 4°C. The higher the water temperature, the shorter the time required for incubation.
For fry cultivation, cement ponds are preferable. A small amount of manure fertilizer water should be applied appropriately in the pond for tubifex reproduction, and aquatic plants such as water hyacinth should be grown on the water surface. The fry stocking density is about 200 per sq m. After 1-2 months, when the eel fry grow to about 10 cm, they can be moved to adult eel ponds for rearing.
Disease Prevention and Control
8-10 days before stocking rice field eels, use quicklime at 100 g/sq m to disinfect the pond. During the farming process, every 30 days insert a pipe into the pond bottom to infuse a 20 ppm calcium peroxide solution to increase oxygen at the pond bottom, preventing the bottom silt from rotting due to lack of oxygen and causing disease in the rice field eels. Every 15 days, splash the entire pond with 15 mmp quicklime for disinfection. In addition, every 5 days, use 20 g of allicin per 100 kg of rice field eels, feeding once daily for 3 consecutive days, to prevent disease. Common diseases of rice field eels include:
Tail rot disease: In the early stage, the tail of the rice field eel becomes congested and inflamed, the muscles undergo necrosis and ulceration, and reactions become sluggish. In severe cases, the tail rots off, and the eel eventually loses mobility and dies. Prevention and treatment methods: prevent injury to seed stock during transport, avoid excessive stocking density, pay attention to frequently changing clean water sources, and splash the entire pond with eel disease remedy.
Skin rot disease: In the early stage, red spots of varying sizes appear on the body surface of the rice field eel, with pinpoint congestion and inflammation, especially obvious on both sides of the abdomen, and weak swimming. When the condition is severe, the epidermis of the diseased eel ulcerates in pinpoint patches, with irregular small holes on the body surface, and infection of internal organs leads to death. Prevention and treatment methods: thoroughly clean the pond with quicklime to eliminate pathogens and prevent contamination. In spring, splash the entire pond with 5-10 ml of eel disease remedy per cubic meter of water, using 3 consecutive days as one treatment course.
Cold: Pay attention to ensuring the temperature difference is not too large when changing water, which can prevent the occurrence of this disease.
Enteritis disease: Diseased eels show reduced appetite, slow swimming, darkened body color, swollen abdomen, and red and swollen anus. Local or entire intestinal congestion and inflammation occur. Prevention and treatment methods: strengthen feeding management, do not feed rotten bait. Soak and wash with 1-2 g of bleaching powder or 10 g of quicklime per cubic meter of water for 5 minutes, and feed with eel stop medicine mixed into the feed for 3 consecutive days.
Capillariasis: Parasitizes inside the eel body, causing the fish to become emaciated and die, accompanied by edema and red and swollen anus. Use 0.1 g of 90% crystalline trichlorfon per kg of rice field eel, mix into the feed and feed for 6 consecutive days.
Artificial Fattening
Pond construction: Rice field eel farming ponds should be built in wind-sheltered, sunny places with guaranteed water sources and relatively solid soil. Cement ponds, earthen ponds, and rice field farming are all acceptable. The pond area for farming rice field eels depends on the scale of farming, generally 20-100 sq m is suitable, with a pond depth of 70 cm. The pond wall should be about 30 cm above the water surface to prevent the rice field eels from escaping. The pond shape is best as a long oval. The pond perimeter should be built with bricks, and the top of the pond side wall should be made into a "t" shape with an overhang of about 20 cm. The pond bottom should be paved with cement, and then about 25 cm of pond mud should be spread on top to facilitate the rice field eels burrowing and hiding. The cement in the pond should not be too deep, preferably maintained at about 15 cm. Drainage holes should be equipped with low-lying anti-escape ponds and old nylon nets. One-third of the pond water surface area should be planted with aquatic plants such as water hyacinth, serving as shade and hiding habitat for the rice field eels.
For eel stocking, the seed stock should preferably come from artificially bred and domesticated excellent dark yellow large-spotted rice field eels. The eel fry should mainly be wild, selecting seed stock with no body damage, no parasites, strong physique, and uniform size, 60-80 fish per kg, stocking about 1 kg of rice field eel fry per sq m. For eel fry of 20-30 fish/kg, the stocking density is 3-4 kg/sq m; for eel fry of 10-20 fish/kg, the stocking density is 4-6 kg/sq m. Eel fry of different sizes should be raised in separate ponds, and at the same time, a small amount of loach should be added at a ratio of 10%.
Feeding management 1. Feed feeding: Rice field eel feed can be earthworms, river mussel meat, snail meat, small miscellaneous fish, small tadpoles, small insects, animal viscera, and fruits and vegetables. Rice field eels hide by day and come out at night. Within one week after stocking, generally feed after dark in the afternoon, then gradually advance the feeding time, training them until they can be fed at 2 PM at the earliest; the feeding rate for fresh bait is 5%-6%, and the feeding rate for dry bait is 1%-2%, with adjustments based on water temperature. The animal-based bait to be fed must be fresh. 2. Daily management: mainly maintain the water quality as "fertile, lively, tender, and refreshing." When just stocking, the pond water should be shallower, preferably 10 cm, then gradually deepen the water level, generally maintained at 15-20 cm. Water should be changed frequently, once every 3 days, with 1/2 of the water changed each time. In summer during high temperatures, change water once daily, preferably in the early morning, when the temperature of the water source is basically consistent with the pond water temperature, preventing the rice field eels from catching "cold" due to too large a temperature difference (greater than 3 degrees). Every morning, promptly remove dead eels, diseased eels, and weak eels. Vine plants such as loofah and grapes can be planted along the pond edge for shade and cooling.
Three Farming Methods
Rice Field Eel Cage Farming
Cage farming is suitable for large water bodies. The main advantage is that water flows through the mesh, creating a flowing water environment inside the cage, resulting in fresh water quality and rich dissolved oxygen, allowing for high-density intensive farming. The main farming techniques are as follows:
The cage area is best at about 20 sq m, with a net length of 5 m, width of 4 m, and height of 1 m, with the above-water part being 40 cm and the underwater part being 60 cm. The net quality should be good, the mesh should be dense, and the net strips should be tight. The cages should be set in ponds with a water depth of 0.8 m or more. The cages can be arranged side by side in the pond, with bamboo racks built between the two rows of cages for walking and feeding management. The cage installation area should not exceed 50% of the total pond area, otherwise it easily causes water quality deterioration. Aquatic plants should be placed in the cages, preferably water peanut, with a coverage area of 90-95% of the cage area.
Rice Field Eel Plastic Greenhouse Soilless Flowing Water Farming
Using plastic greenhouses to farm rice field eels allows continuous production throughout the year. Soilless flowing water farming can effectively control diseases and multiply benefits. Plastic greenhouse soilless flowing water farming mainly has the following two methods:
(1) Open type. Suitable for building ponds in places with warm flowing water year-round, suitable for larger-scale operations. The rearing ponds are built with bricks and cement, each pond with an area of 10-20 sq m, pond depth of 40 cm, width of 1-2 m, and pond ridge width of 20-40 cm. At opposite positions in the pond, install 2 inlet pipes and 2 drainage pipes each with a diameter of 3-4 cm. (2) Closed recirculating filtration type. Suitable for use in large cities or places lacking water sources. The rearing water can be reused, with relatively low water consumption and easy temperature control, but the investment is slightly larger. In addition, aeration ponds and sedimentation ponds need to be built, along with some water purification equipment, pumping equipment, and heating equipment.
Rice Field Eel Rice Field Farming
Using rice fields to farm rice field eels has low cost and is convenient to manage. It produces both rice grain and fish, and is an effective way for farmers to increase income. Selection and requirements of rice fields: Rice fields for farming rice field eels should be selected with good water retention, low-lying terrain, and convenient irrigation and drainage. First, raise and reinforce the field ridges to achieve no seepage or leakage. Second, dig a set of surrounding trenches inside and outside the field perimeter, with a width of 5 m and depth of 1 m. In addition, dig "+" or "well"-shaped small trenches in the middle of the field, with a width of 50 cm and depth of 30 cm, connected to the surrounding trenches. Third, establish a good irrigation and drainage system, and install sturdy fish-blocking facilities at the inlet and outlet to prevent fish from escaping. The seed stocking time is concentrated in mid-to-late April with a one-time full stocking. When stocking fingerlings, soak and wash them in 3%-4% salt water for 10 minutes to prevent epidermal abrasions and kill water mold and external parasites.