Device and method for improving survival rate of monopterus albus fries in pond

Abstract

The invention discloses a device and method for increasing the survival rate of monopterus albus fries in a pond, the device comprises net cages, a sunshade net, a water inlet device and a feeding box, and 30 net cages are erected in each mu of the pond; the sunshade net is provided with 5 needles and 65% of sunshade rate, and is erected at a position 10-20 cm right above the net cage; the water inlet device comprises a submersible pump and a water inlet pipe, the water inlet pipe is erected right above the net cages, and each net cage corresponds to one water inlet, so that exchange of water inside and outside the net cages can be increased, deterioration of water quality is avoided, and water temperature in the net cages can be reduced; the edge of the feeding box is adhered with a foam ring, so that the feeding box floats on the water surface; according to the method, the water temperature is effectively reduced, bird damage is prevented, the ingestion efficiency is improved, diseases are reduced, and the survival rate of ricefield eel fries in one month after the ricefield eel fries are put into the pond reaches 90% or above; the method is easy to operate, low in cost, capable of remarkably improving the monopterus albus fry breeding effect and suitable for large-scale application and popularization.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically relating to a device and method for improving the survival rate of juvenile eel seedlings after stocking. Background Technology

[0002] The swamp eel, an important freshwater economic fish in my country, is prized for its delicious and nutritious meat, making it a popular choice among consumers and possessing high economic value. However, the development of the swamp eel industry has long been severely constrained by a shortage of seedlings. Currently, the swamp eel farming industry mainly relies on wild-caught seedlings, but the low survival rate of wild seedlings leads to poor farming efficiency and fails to meet the industry's development needs. With the gradual development of swamp eel farming, the demand for seedlings is increasing year by year. In recent years, the techniques for simulated ecological breeding and artificial breeding of swamp eels have been continuously improved, which has promoted the development of the swamp eel farming industry to some extent. However, swamp eel seedling cultivation technology is still immature, and the survival rate of seedlings is low, especially the mortality rate within one month after stocking, which has become a key factor restricting the further development of the swamp eel industry. The main reasons for the low survival rate of eel fry are as follows: First, high temperature affects the eel fry, which are delicate and sensitive and are prone to stress-induced death in high-temperature environments; second, excessive stocking density and uneven feeding lead to different growth rates of the fry, and if they are not graded and separated in time, cannibalism will occur; third, there are many defects in the existing breeding technology.

[0003] Patent CN112237158A discloses a method for the factory-scale cultivation of swamp eel fry. This method utilizes factory-scale cultivation facilities, employing a constant-temperature greenhouse, equipped with an air-source heat pump to control water temperature, and also includes physical filtration, biological filters, ultraviolet sterilization processors, and an aeration system. While this method can guarantee the cultivation environment to a certain extent, it requires the use of various expensive equipment, resulting in high cultivation costs and hindering large-scale application. Patent CN112056244A relates to a method for cultivating swamp eel fry using mesh cages, employing nested use of small, medium, and large fry cages. However, this method cannot avoid high mortality rates due to high temperatures and feeding problems with outdoor birds. Furthermore, directly feeding live tubifex worms inside the cages can cause the worms to escape through the mesh, making it difficult to accurately assess feeding activity and resulting in significant losses.

[0004] Therefore, it is necessary to develop a device and method that can effectively improve the survival rate of eel fry after stocking, is simple to operate, and has low cost, which is of great significance for promoting the healthy development of the eel farming industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as low survival rate, high cost, and complex operation in the cultivation of eel fry, and to provide a device and method for improving the survival rate of eel fry after they are released into ponds.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A device for improving the survival rate of swarm eel fry in a pond includes a pond (1), in which multiple net cages (6) are arranged in an array. The net cages (6) are 20 cm above the water surface. Each net cage (6) is surrounded by wooden stakes (3) and has a feeding box (8) inside. The feeding box (8) is a cubic structure made of high-density polyethylene (HDPE). Foam rings (10) are attached to the edges of the feeding box (8) so that the feeding box (8) floats on the water surface. Each of the four sides has four inlets and outlets (11) with a diameter of 15 cm. A shade net (2) is installed 10-20 cm above the net cages (6). The shade net (2) has a 5-needle 65% shading rate and is fixed to the wooden stakes (3) by steel wire. A water inlet pipe (4) is installed above each net cage (6) and is connected to a submersible pump (5).

[0008] In a preferred embodiment of the present invention, the net cage (6) is made of nylon mesh with a mesh size of 40 meshes and the net cage (6) has a size of 1m×1m×0.8m.

[0009] In a preferred embodiment of the present invention, the inlet / outlet (11) is located 3-5 cm away from the bottom of the feeding box (8).

[0010] In a preferred embodiment of the present invention, the feeding box (8) has a size of 0.4m × 0.4m × 0.4m.

[0011] In a preferred embodiment of the present invention, an oxygenation device (9) is provided on both the front and rear sides of the pond (1).

[0012] In a preferred embodiment of the present invention, 3-5 water hyacinths (7) are also planted inside each feeding box (8).

[0013] In a preferred embodiment of the present invention, the net cages (6) are installed at a density of 30 cages per mu of pond.

[0014] This invention also provides a method for improving the survival rate of eel fry after stocking, which is achieved using the aforementioned device for improving the survival rate of eel fry after stocking, and includes the following steps:

[0015] Step 1, Pond Preparation: Select a pond far away from residential areas, livestock and poultry breeding areas, and industrial pollution areas. Ensure access to water, electricity, and roads. The pond area should be 5-20 mu (approximately 0.33-0.33 hectares) with a water depth of 1.5-2.0 m. Equip the pond with a ring ditch 8-10 meters wide and 2-3 meters deep for water conditioning in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Begin sun-drying the pond from late February to early March until cracks are visible in the bottom mud. At the end of April, spray the pond with 80-100 catties / mu (approximately 40-50 kg / mu) of quicklime mixed with water, and simultaneously clean the river mussels from the bottom of the pond. Complete the installation of net cages, water inlet devices, and shade nets by mid-May. Before setting up the net cages, soak them in water for 2-3 days.

[0016] Step 2, Seedling release: Collect artificial or semi-natural eel fry in May and June, and release them into net cages. Release 300-500 eel fry (3-5cm) into each net cage.

[0017] Step 3, Feeding Management: Place one feeding box in each net cage, and plant 3-5 healthy water hyacinths with well-developed root systems in the feeding box; feed tubifex worms every other day, 40-50g per net cage each time. Rinse the tubifex worms with well water for 24 hours before feeding, and turn them over every 2 hours during the day to ensure that they are turned over 6-8 times a day to wash away impurities and dead individuals from the tubifex worms and prevent the eel fry from getting sick and dying after feeding.

[0018] In a preferred embodiment of the present invention, step 2 includes: after the eel fry are released, a 5-needle shade net with a 65% shading rate is erected 10-20cm directly above each net cage, which can effectively prevent birds from feeding on it and at the same time reduce the water temperature in hot weather; the submersible pump is turned on for 1-3 hours every day from 9-10 am to increase the exchange of water inside and outside the pond, which can maintain the water quality in the net cage and at the same time reduce the water temperature in the hot season. According to the measurement, the water temperature in the net cage after the shade net and water inlet device are erected is 2-3 degrees lower than the water temperature in the net cage without the shade net and water inlet device, which can effectively reduce the mortality of eel fry caused by high temperature.

[0019] In a preferred embodiment of the present invention, step 2 includes: after the eel fry are placed in the net cage, a feeding box with a size of 0.4m×0.4m×0.4m is placed in each net cage. The top of the feeding box is glued with a foam ring using 520 glue to facilitate the feeding box floating on the water surface. 3-5 water hyacinths with good growth and well-developed root systems are planted in the feeding box. Taking advantage of the eel fry's preference for shade and their natural tendency to attach to roots, the eel fry are induced to stay in the feeding box. At the same time, an inlet and outlet with a diameter of 15cm is set 3-5cm from the bottom of the feeding box to facilitate the entry and exit of the eel fry, while preventing the escape of the tubifex worms at the bottom, improving feeding efficiency, and facilitating the observation of remaining feed and the mortality of the eel fry.

[0020] Compared with the prior art, the embodiments of the present invention provide a device and method for improving the survival rate of eel fry after stocking, which has the following beneficial effects:

[0021] (1) Effectively reduce water temperature: By setting up a 5-needle shade net with a 65% shading rate above the net cage, and at the same time setting up a water inlet device above the net cage, the water exchange inside and outside the net cage is increased, which can make the water temperature in the net cage 2-3 degrees lower than that in the net cage without shade net and water inlet device, thus avoiding stress-induced death of eel seedlings due to high temperature and providing a suitable growth temperature environment for the seedlings.

[0022] (2) Significant bird protection effect: Shade nets can block birds from approaching the net cages, reduce birds' feeding on the eel seedlings, and improve the survival rate of the seedlings.

[0023] (3) Improve feeding efficiency: Set up feeding boxes with specific openings and plant water hyacinths in the boxes to induce the eel fry to gather and feed, while preventing the water worms from escaping. This makes it easier to observe the feeding situation and clean up the remaining feed, thus improving feeding efficiency and opening rate.

[0024] (4) Reduce the risk of disease outbreaks: Rinse the tubifex worms with well water for 24 hours and turn them over multiple times to effectively remove pathogens carried by the tubifex worms and reduce the occurrence of diseases.

[0025] (5) Optimize the stocking density: 300-500 eel fry of 3-5cm are stocked per square meter of net cage to avoid uneven growth and cannibalism caused by excessive density, and reduce mortality.

[0026] (6) Simple operation and low cost: This invention optimizes the traditional net cage seedling cultivation method. The equipment materials used are readily available, easy to manufacture and set up, and do not require expensive equipment, thus reducing cultivation costs and making it suitable for large-scale promotion and application.

[0027] In summary, the device and method of the present invention can significantly improve the survival rate of eel fry after stocking, providing strong technical support for the eel farming industry and having broad application prospects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a device for improving the survival rate of swarm eel fry after being planted in ponds, as provided in this application embodiment.

[0030] Figure 2 This application provides a schematic diagram of a feeding box.

[0031] Attached diagram labels: 1. Pond, 2. Shade net, 3. Wooden stake, 4. Inlet pipe, 5. Submersible pump, 6. Net cage, 7. Water hyacinth, 8. Feeding box, 9. Aerator, 10. Foam ring, 11. Inlet / outlet. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The terms "upper," "lower," "front," "rear," "left," and "right," etc., used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation shown in the accompanying drawings. They are merely for convenience of description, used to distinguish the relative positions of various components or directions, and do not represent the orientation of the system or functional components in this embodiment during use.

[0033] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a device for improving the survival rate of swarm eel fry in ponds. The device includes a pond 1, within which multiple net cages 6 are arranged in an array at a density of 30 cages per acre of pond. The net cages 6 are positioned 20 cm above the water surface. Each net cage 6 is surrounded by wooden stakes 3 and contains a feeding box 8. The feeding box 8 is a cubic structure made of high-density polyethylene (HDPE), with foam rings 10 attached to its edges to allow it to float on the water surface. Each of its four sides has four inlets / outlets 11 with a diameter of 15 cm. A shade net 2, with a 5-needle design and a 65% shading rate, is installed 10-20 cm directly above each net cage 6 and is fixed to the wooden stakes 3 by steel wire. A water inlet pipe 4 is installed above each net cage 6 and connected to a submersible pump 5.

[0034] Net cage 6 is made of nylon netting with a mesh size of 40 meshes and measures 1m × 1m × 0.8m. This mesh size prevents eel fry from escaping while ensuring normal water circulation, providing a good growth environment for the fry. The 1m × 1m × 0.8m size of net cage 6 facilitates management and operation, while providing suitable space for the eel fry to move around. Net cages 6 are installed at a density of 30 cages per acre of pond, with the top of the cages 20cm above the water. This setup prevents eel fry from escaping and ensures a stable living environment for the fry.

[0035] A water inlet pipe 4 is installed above the net cage 6. The water inlet pipe 4 is connected to a submersible pump 5. By pumping water from the middle layer of the pond into each net cage, the exchange of water inside and outside the net cage can be increased, the accumulation of debris caused by the clogging of the mesh can be avoided, the water quality can be prevented from deteriorating, and the water temperature inside the net cage can be reduced.

[0036] The 5-needle, 65% shade net effectively blocks some sunlight, lowers the water temperature in the net cage 6, and prevents stress damage to the eel fry caused by high temperatures. At the same time, the shade net 2 provides a darker environment for the eel fry, which is in line with the natural habits of eels and is conducive to the healthy growth of the eel fry. In addition, the shade net can also prevent birds from feeding on the eel fry.

[0037] The feeding box 8 measures 0.4m × 0.4m × 0.4m and is made of HDPE. HDPE material has advantages such as corrosion resistance and good stability, making it suitable for long-term use in water. Foam rings 10 are attached to the edges of the feeding box 8, allowing it to float on the water surface, facilitating access and feeding for eel fry. The feeding box 8 has multiple 15cm diameter inlets and outlets 11 on each of its four sides, facilitating the entry and exit of eel fry. The inlets and outlets 11 are located 3-5cm from the bottom of the feeding box 8. Taking advantage of the fact that tubifex worms like to congregate, placing the worms at the bottom of the feeding box effectively prevents them from escaping, facilitates observation of the eels' feeding behavior, improves feeding efficiency, and makes it easy to clean up any remaining worms, preventing water quality deterioration.

[0038] A set of aeration equipment 9 is set up on both the front and back sides of pond 1. Each feeding box 8 is also planted with 3-5 water hyacinths 7. Taking advantage of the eel fry's preference for shade and their natural tendency to attach to roots, the eel fry are induced to stay in the feeding box, increasing the opening rate and feeding rate. The water hyacinths are used as habitats for the eel fry and make it easier for them to feed on the water worms inside the feeding box.

[0039] The present invention, through measures such as setting up net cages in outdoor ponds, equipping them with special feeding boxes, installing shade nets, installing water inlets, equipping the ponds with aeration equipment, and rationally controlling density and feeding strategies, effectively reduces water temperature, ensures water quality, prevents birds, and improves feeding efficiency, resulting in a high survival rate of fry. By installing shade nets and water inlets above the net cages, the water temperature can be effectively reduced, preventing fry mortality due to high temperatures; the shade nets provide a darker environment for the eel fry, conforming to their natural habits and promoting healthy growth; the shade nets also serve a bird-proof function; the water inlet device, including a submersible pump and inlet pipe, improves water exchange between the inside and outside of the net cages, preventing mesh blockage and water quality deterioration inside the cages. By setting up feeding boxes with eel fry inlets and outlets on all four sides, and planting water hyacinths above the feeding boxes, the eel fry are induced to gather in the feeding boxes, taking advantage of their preference for shade and attachment to water hyacinth roots, thus improving feeding efficiency, opening rate, and survival rate. By setting up feeding boxes with inlets and outlets on all four sides, positioned 3-5 cm from the bottom of the box, and taking advantage of the tubifex worms' tendency to congregate, placing the worms at the bottom of the feeding box effectively prevents them from escaping. This also facilitates observation of the eels' feeding behavior, improving feeding efficiency and making it easier to remove dead worms and prevent water contamination. Optimizing the stocking density to 300-500 eel fry per square meter of net cage effectively reduces the high mortality rate caused by overcrowding. Using well water to flush the tubifex worms 24 hours a day effectively prevents the introduction of pathogens, reducing the risk of disease outbreaks. This optimized traditional net cage fry cultivation method is simple to operate and low in cost.

[0040] This invention provides a method for improving the survival rate of eel fry after stocking, which is achieved using the aforementioned device for improving the survival rate of eel fry after stocking, and includes the following steps:

[0041] Step 1, Pond Preparation: Select a pond far away from residential areas, livestock and poultry breeding areas, and industrial pollution areas. Ensure access to water, electricity, and roads. The pond area should be 5-20 mu (approximately 0.33-0.33 hectares) with a water depth of 1.5-2.0 m. Equip the pond with a ring ditch 8-10 meters wide and 2-3 meters deep for water conditioning in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Start sun-drying the pond from late February to early March until cracks are visible in the bottom mud. At the end of April, spray quicklime mixed with water at a rate of 80-100 catties / mu (approximately 40-50 kg / mu) while cleaning the river mussels at the bottom of the pond. Complete the installation of net cages and shade nets by mid-May. Before setting up the net cages, soak them in water for 2-3 days.

[0042] This embodiment selects ponds far from densely populated residential areas, livestock and poultry breeding areas, and industrial pollution areas to ensure unpolluted water quality and provide a clean growth environment for eel fry. The ponds must have access to water, electricity, and roads for convenient daily management and operation. The pond area is 5-20 mu (approximately 0.33-0.33 hectares), with a water depth of 1.5-2.0 meters. This size and depth are conducive to water stability and temperature regulation. The ponds are equipped with a ring ditch 8-10 meters wide and 2-3 meters deep for water conditioning in the ponds for silver carp and bighead carp. These fish can filter plankton from the water, thus purifying the water. An intelligent and automated system is installed to monitor water quality physicochemical indicators and control oxygenation equipment, allowing for real-time monitoring of water quality and timely oxygenation to ensure excellent water quality. From late February to early March, the ponds are sun-dried until cracks are visible in the bottom mud. Sun-drying kills pathogens and pests in the bottom mud and improves the bottom environment. At the end of April, spray quicklime mixed with water at a rate of 80-100 catties / mu. Quicklime has a disinfecting and sterilizing effect, further purifying the pond environment. At the same time, clean up the river mussels at the bottom of the pond to prevent them from polluting the water after they die. Complete the installation of net cages and shade nets in mid-May. Before setting up the net cages, soak them in water for 2-3 days to reduce the abrasion of the net surface on the eel fry.

[0043] Step 2, Seedling release: Collect artificial or semi-natural eel fry in May and June, and release them into net cages. Release 300-500 eel fry (3-5cm in length) into each net cage.

[0044] In this embodiment, artificially raised or semi-natural eel fry were collected in May and June, when the fry were in good condition and had strong adaptability. They were then released into net cages, with 300-500 fry (3-5cm in length) per cage. By optimizing the stocking density, the mortality rate caused by overcrowding was effectively reduced.

[0045] Step 3, Feeding Management: Place one feeding box in each net cage, and plant 3-5 healthy water hyacinths with well-developed root systems in the feeding box; feed each net cage 40-50g of tubifex worms each time, every other day, to avoid liver and gallbladder problems caused by overfeeding. Rinse the tubifex worms with well water for 24 hours before feeding, and turn them over every 2 hours during the day to ensure that they are turned over 6-8 times a day to wash away impurities and dead individuals from the tubifex worms and prevent the eel fry from getting sick and dying after feeding.

[0046] In this embodiment, each net cage is equipped with one feeding box, containing 3-5 healthy water hyacinths with well-developed root systems. Taking advantage of the eel fry's preference for shade and their tendency to attach to the water hyacinth roots, the feeding box encourages them to gather, increasing feeding efficiency, opening rate, and survival rate. Tubifex worms are fed every other day, 40-50g per cage per feeding, with no feeding the following day. This feeding strategy avoids water quality deterioration and liver and gallbladder problems caused by overfeeding, while simultaneously promoting the feeding enthusiasm of the eel fry. The tubifex worms are rinsed with well water for 24 hours before feeding, and turned every 2 hours during the day, ensuring 6-8 times daily cleaning. This thoroughly cleans the worms, effectively preventing the introduction of pathogens into the breeding environment and reducing the risk of disease outbreaks.

[0047] Preferably, step 2 further includes: after the eel fry are released, a 5-needle shade net with a 65% shading rate is erected 10-20cm directly above each net cage. This effectively prevents birds from feeding on the eel and lowers the water temperature during hot weather. The water inlet device includes a submersible pump and an inlet pipe. An inlet pipe is erected above each net cage and connected to the submersible pump. The submersible pump is turned on for 1-3 hours daily from 9-10 am to increase water exchange between the inside and outside of the pond, maintain water quality in the net cages, and lower the water temperature during hot seasons. This effectively increases water exchange between the inside and outside of the net cages, prevents the accumulation of large amounts of debris in the net cages, prevents water quality deterioration, and lowers the water temperature inside the net cages. Measurements have shown that the water temperature in the net cages after installing the shade net and water inlet device is 2-3 degrees Celsius lower than that in net cages without the shade net and water inlet device, effectively reducing the mortality of eel fry caused by high temperatures.

[0048] Preferably, step 2 includes: after the eel fry are placed in the net cage, a feeding box with a size of 0.4m×0.4m×0.4m is placed in each net cage. The top of the feeding box is glued with a foam ring using 520 glue to facilitate the feeding box floating on the water surface. 3-5 healthy water hyacinths with well-developed root systems are planted in the feeding box. Taking advantage of the eel fry's preference for shade and their natural tendency to attach to roots, the eel fry are induced to stay in the feeding box. At the same time, an inlet and outlet with a diameter of 15cm is set 3-5cm from the bottom of the feeding box to facilitate the entry and exit of the eel fry, while preventing the escape of the tubifex worms at the bottom, improving feeding efficiency, and facilitating the observation of remaining feed and the mortality of the eel fry.

[0049] Example 1

[0050] A method to improve the survival rate of eel fry after stocking in ponds, the specific steps of which are as follows:

[0051] Step 1, Pond Preparation: Select a pond 10 mu (approximately 1.65 acres) away from densely populated residential areas, livestock and poultry breeding areas, and industrial pollution areas. The pond should be 1.8 meters deep and equipped with a 9-meter-wide, 2.5-meter-deep ring ditch for water management in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Begin sun-drying the pond in late February; by early March, cracks should be visible in the bottom mud. At the end of April, spray quicklime mixed with water at a rate of 90 jin (approximately 45 catties) per mu (approximately 1.5 kg / acre), while simultaneously cleaning the river mussels from the bottom of the pond. Complete the installation of net cages, shade nets, and water inlet devices by mid-May. The net cages should be 1m × 1m × 0.8m, made of 40-mesh nylon netting. Soak the cages in water for 2 days before installation. Install 30 net cages per mu (approximately 1.65 acres), with the top of the net cages 20 cm above the water. The shade nets should be 5-needle nets with a 65% shading rate, installed 15 cm directly above the net cages and secured to wooden stakes with steel wire. The water intake device includes an inlet pipe and a submersible pump. The inlet pipe is installed above the net cage and connected to the submersible pump. The submersible pump is installed in the middle water level of the pond and runs for 1 hour every day from 9 to 10 am.

[0052] Step 2, Seedling Release: In mid-May, collect 1 million artificial eel fry and release them into 2,000 net cages, with 500 eel fry of 3-5cm in length released into each net cage.

[0053] Step 3, Feeding Management: Place one 0.4m × 0.4m × 0.4m feeding box in each net cage. The feeding box is made of HDPE, with foam glued to the edges to float on the water surface. Each of the four sides has four 15cm diameter openings, 4cm from the bottom. Plant four healthy water hyacinths with well-developed root systems inside the feeding box. Feed with tubifex worms every other day, 45g per cage per feeding. Rinse the tubifex worms with well water for 24 hours before feeding. Turn them over every 2 hours during the day, 7 times a day.

[0054] After one month of cultivation, the survival rate of the eel fry reached 92%.

[0055] Example 2

[0056] A method to improve the survival rate of eel fry after stocking in ponds, the specific steps of which are as follows:

[0057] Step 1, Pond Preparation: Select a pond 5 mu (approximately 0.33 hectares) away from densely populated residential areas, livestock and poultry breeding areas, and industrial pollution areas. The pond should be 1.5 meters deep and equipped with an 8-meter-wide, 2-meter-deep ring ditch for water management in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Begin sun-drying the pond in late February; by early March, cracks should be visible in the bottom mud. At the end of April, spray quicklime mixed with water at a rate of 80 jin (approximately 40 catties) per mu (approximately 0.067 hectares), while simultaneously cleaning the river mussels from the bottom of the pond. Complete the installation of net cages, water inlet devices, and shade nets by mid-May. The net cages should be 1m × 1m × 0.8m, made of 40-mesh nylon netting. Soak the net cages in water for 3 days before installation. Install 30 net cages per mu (approximately 0.067 hectares), with the top of the net cages 20 cm above the water. The shade nets should be 5-needle netting with a 65% shading rate, installed 10 cm directly above the net cages and secured to wooden stakes with steel wire. The water intake device includes an inlet pipe and a submersible pump. The inlet pipe is installed above the net cage and connected to the submersible pump. The submersible pump is installed in the middle water level of the pond and runs for 2 hours every day from 9 to 10 am.

[0058] Step 2, Seedling Release: In early June, collect 3 million artificial eel fry and release them into 1,000 net cages, with 300 eel fry of 3-5cm in length released into each net cage.

[0059] Step 3, Feeding Management: Place one 0.4m × 0.4m × 0.4m feeding box in each net cage. The feeding box is made of HDPE, with foam glued to the edges to float on the water surface. Each of the four sides has four 15cm diameter openings, 3cm from the bottom. Plant three healthy water hyacinths with well-developed root systems inside the feeding box. Feed with tubifex worms every other day, 40g per cage per feeding. Rinse the tubifex worms with well water for 24 hours before feeding. Turn them over every 2 hours during the day, 6 times a day.

[0060] After one month of cultivation, the survival rate of the eel fry reached 90%.

[0061] Example 3

[0062] A method to improve the survival rate of eel fry after stocking in ponds, the specific steps of which are as follows:

[0063] Step 1, Pond Preparation: Select a pond 20 mu (approximately 3.3 hectares) away from densely populated residential areas, livestock and poultry breeding areas, and industrial pollution areas. The pond should be 2.0 meters deep and equipped with a 10-meter-wide, 3-meter-deep ring ditch for water management in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Begin sun-drying the pond in late February; by early March, cracks should be visible in the bottom mud. At the end of April, spray quicklime mixed with water at a rate of 100 catties / mu (approximately 50 kg / hectare) while simultaneously cleaning the river mussels from the bottom of the pond. Complete the installation of net cages, water intake devices, and shade nets by mid-May. The net cages should be 1m × 1m × 0.8m, made of 40-mesh nylon netting. Soak the net cages in water for 2 days before installation. Install 30 net cages per mu (approximately 0.067 hectares), with the top of the net cages 20 cm above the water. The shade nets should be 5-needle netting with a 65% shading rate, installed 20 cm directly above the net cages and secured to wooden stakes with steel wire. The water intake device includes an inlet pipe and a submersible pump. The inlet pipe is installed above the net cage and connected to the submersible pump. The submersible pump is installed in the middle water level of the pond and runs for 3 hours every day from 9 to 10 am.

[0064] Step 2, Seedling Release: In late May, collect 2 million artificial eel fry and release them into 4,000 net cages, with 400 eel fry of 3-5cm in length released into each net cage.

[0065] Step 3, Feeding Management: Place one 0.4m × 0.4m × 0.4m feeding box in each net cage. The feeding box is made of HDPE, with foam glued to the edges to float on the water surface. Each of the four sides has four 15cm diameter openings, 5cm from the bottom. Plant five healthy water hyacinths with well-developed root systems inside the feeding box. Feed with tubifex worms every other day, 50g per cage per feeding. Rinse the tubifex worms with well water for 24 hours before feeding. Turn them over every 2 hours during the day, 8 times a day.

[0066] After one month of cultivation, the survival rate of the eel fry reached 91%.

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for improving the survival rate of juvenile eel fry after stocking, characterized in that, The system includes a pond (1), in which multiple net cages (6) are arranged in an array. The net cages (6) are 20 cm above the water surface. Each net cage (6) is surrounded by wooden stakes (3) and has a feeding box (8) inside. The feeding box (8) is a cubic structure made of high-density polyethylene (HDPE). Foam rings (10) are attached to the edges of the feeding box (8) so that the feeding box (8) floats on the water surface. Each of the four sides has four inlets and outlets (11) with a diameter of 15 cm. A shade net (2) is installed 10-20 cm above the net cages (6). The shade net (2) has a 5-needle 65% shading rate and is fixed to the wooden stakes (3) by steel wire. A water inlet pipe (4) is installed above each net cage (6) and is connected to a submersible pump (5).

2. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, The net cage (6) is made of nylon net with a mesh size of 40 meshes and the net cage (6) has a size of 1m×1m×0.8m.

3. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, The inlet / outlet (11) is located 3-5 cm from the bottom of the feeding box (8).

4. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, The feeding box (8) has dimensions of 0.4m × 0.4m × 0.4m.

5. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, A set of aeration equipment (9) is set on both the front and back sides of the pond (1).

6. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, Each feeding box (8) contains 3-5 water hyacinths (7).

7. The device for improving the survival rate of eel fry in ponds according to claim 1, characterized in that, The net cages (6) are installed at a density of 30 cages per mu of pond.

8. A method for improving the survival rate of eel fry after stocking, implemented using the apparatus for improving the survival rate of eel fry as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1, Pond Preparation: Select a pond far away from residential areas, livestock and poultry breeding areas, and industrial pollution areas. Ensure access to water, electricity, and roads. The pond area should be 5-20 mu (approximately 0.33-0.33 hectares) with a water depth of 1.5-2.0 m. Equip the pond with a ring ditch 8-10 meters wide and 2-3 meters deep for water conditioning in silver carp and bighead carp farming. Install an intelligent and automated system for monitoring water quality physicochemical indicators and controlling aeration equipment. Begin sun-drying the pond from late February to early March until cracks are visible in the bottom mud. At the end of April, spray the pond with 80-100 catties / mu (approximately 40-50 kg / mu) of quicklime mixed with water, and simultaneously clean the river mussels from the bottom of the pond. Complete the installation of net cages, water inlet devices, and shade nets by mid-May. Before setting up the net cages, soak them in water for 2-3 days. Step 2, Seedling release: Collect semi-natural or fully artificially bred eel seedlings in May and June, and release them into net cages. Each net cage should contain 300-500 eel seedlings of 3-5cm in length. Step 3, Feeding Management: Place one feeding box in each net cage, and plant 3-5 healthy water hyacinths with well-developed root systems in the feeding box; feed tubifex worms every other day, 40-50g per net cage each time. Rinse the tubifex worms with well water for 24 hours before feeding, and turn them over every 2 hours during the day to ensure that they are turned over 6-8 times a day to wash away impurities and dead individuals from the tubifex worms and prevent the eel fry from getting sick and dying after feeding.

9. The method for improving the survival rate of eel fry after stocking according to claim 8, characterized in that, Step 2 includes: After the eel fry are released, a 5-needle shade net with a 65% shading rate is set up 10-20cm directly above each net cage. This can effectively prevent birds from feeding on the eels and lower the water temperature during hot weather. The submersible pump is turned on for 1-3 hours every day from 9-10 am to increase the exchange of water inside and outside the pond. This can maintain the water quality in the net cages and lower the water temperature during the hot season. According to measurements, the water temperature in the net cages after setting up the shade nets and water inlet devices is 2-3 degrees lower than that in net cages without shade nets and water inlet devices, which can effectively reduce the mortality of eel fry caused by high temperatures.

10. The method for improving the survival rate of eel fry after stocking according to claim 8, characterized in that, Step 2 includes: After the eel fry are released, each net cage is equipped with a feeding box measuring 0.4m × 0.4m × 0.4m. The top of the feeding box is glued with a foam ring using 520 glue to facilitate its floating on the water surface. 3-5 healthy water hyacinths with well-developed root systems are planted inside the feeding box. Taking advantage of the eel fry's preference for shade and their natural tendency to attach to roots, the eel fry are induced to stay inside the feeding box. At the same time, an inlet and outlet with a diameter of 15cm is set 3-5cm from the bottom of the feeding box to facilitate the entry and exit of the eel fry, while preventing the escape of the tubifex worms at the bottom, improving feeding efficiency, and making it easier to observe the remaining feed and the mortality of the eel fry.

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