High-temperature and high-density-based practice method and device for ricefield eel fry

Abstract

The application discloses a high-temperature and high-density-based rice field eel training method and device, and the training method is used for training the rice field eel seedlings in a high-temperature and high-density environment, so that the seedlings are trained in the high-temperature and high-density environment, the adaptability of the seedlings to high-density breeding in the later period is improved, and the survival rate of the seedlings in summer is improved; the rice field eels with weak constitution, transport damage and high stress are selected out through a temperature transition period, and then are sold; then, the temperature of water is slowly increased for high-temperature training, the high-temperature training mortality is reduced, and the economic loss is reduced; therefore, the method has the characteristics of low cost and good benefit.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically relating to a method and apparatus for cultivating eel seedlings at high temperature and high density. Background Technology

[0002] The swamp eel (Monopterus albus) is an important freshwater economic fish in my country, but a severe shortage of fry has significantly limited the industry's development. Swamp eel farming is mainly carried out in ponds and cages, with high stocking densities; generally, 20-50g fry are stocked at densities exceeding 2kg / m². 2 High stocking density leads to a high mortality rate in the early stages of seedling release, and eels are sensitive to temperature fluctuations; high summer temperatures easily increase mortality and inhibit growth. Furthermore, eel farming primarily uses wild-caught seedlings, but the sources of these wild seedlings vary, and factors such as harvesting methods, transportation, and storage can easily cause stress reactions in the seedlings, resulting in very low survival rates if directly released into aquaculture. Releasing wild eel seedlings during the cooler months of April and May results in mass mortality within 15 days, with mortality rates sometimes reaching 100%, making wild-caught seedlings a crucial supplement to the current seedling supply.

[0003] The patent application "A device and method for artificially raising and cultivating wild eel fry in advance (CN109006589A)" includes a water storage tank, a heating tank, a cultivation tank, and a sewage tank connected in sequence. 10-15 days before releasing the wild eels, water hyacinths are first cultivated on floating beds in the cultivation tank. The water temperature is adjusted to within the range of 28-30℃ and tested for at least 3 days. Once the temperature in the cultivation tank is maintained within this range, the eels can be released. After purchasing the wild eels, they are graded by weight, and weak, injured, or diseased eels are removed. They are then disinfected with 2% saline solution for 5 minutes and placed in the cultivation tank. Each cultivation tank is stocked with 50-60 kg of eels per 1.8m² pond. 3 The eels placed in each rearing pond must be of uniform size. They are not fed for three days after release to allow them to acclimatize. On the fourth day, they are trained to eat earthworms. For the first seven days, they are fed earthworms daily at 3% of their body weight. Once the wild eels are successfully trained, the feeding amount is increased to 5%-7%. After approximately 45 days of rearing in the ponds, the wild eels can be transferred to net cages in the main pond for further aquaculture. This rearing method is cumbersome, has a long cycle, and is costly.

[0004] The patent application for "Domestication Method of Wild Eel Seedlings in Eel Farming (CN113475432A)" involves placing unpolluted water in a closed, well-insulated cement pond to a certain depth, then placing net cages inside; placing eel nests in the net cages, and then placing wild eel seedlings inside; pressurizing the closed pond to 1030-1100 hPa, slowly raising the pond water temperature to 33-37℃ and maintaining this pressure and temperature control for 3-4 days; and then slowly depressurizing and cooling the water until it matches the outdoor environment, at which point it can be put into large-scale farming. This method requires simultaneous pressure and temperature control, placing high demands on the construction of the breeding pond and the technical skills of the personnel. Furthermore, since all net cages are located in the same cement pond, if an eel in one net cage dies during the training process, the disease can easily spread to eels in other net cages via water, leading to mass mortality and economic losses.

[0005] Therefore, a new method and device for training eel seedlings is needed to solve the problems existing in the current technology. Summary of the Invention

[0006] This invention provides a method and apparatus for cultivating eel seedlings at high temperature and high density, which solves the problems existing in the prior art: eels are sensitive to temperature fluctuations, and high temperatures in summer can easily lead to increased mortality and growth inhibition.

[0007] To solve the above problems, the technical solution provided by the present invention is as follows:

[0008] This invention provides a method for acclimating eel seedlings based on high temperature and high density, comprising the following steps:

[0009] Step 1: Purchase eel fry from the market between April and June. Select eel fry that are of uniform size, healthy, unharmed, and vigorous. Temporarily raise the selected eels in water and transport them back every morning, with the transportation time not exceeding 2 hours.

[0010] Step 2, temporary rearing of seedlings: After being disinfected, the transported eel seedlings are placed in pre-prepared hardening tanks with a density of 1:4 eel seedlings to water and a temperature difference controlled within 2℃. A preliminary screening is conducted for 24 hours to remove eel seedlings that were damaged during transportation or that were under great stress, exhibiting signs of injury, stubble, and poor vitality. The poorly performing eel seedlings are then processed. The screening rate at this stage is 5%-10%, which allows the seedlings to undergo high-density hardening and improves their adaptability to high-density farming in the later stages.

[0011] Step 3, high-temperature training: On the second day, slowly raise the water temperature to the outdoor water temperature when purchasing the eel fry plus 10°C. The temperature rise should be completed within 6 hours, and the high-temperature environment should be maintained for 15 days. During this period, dead eel fry should be screened out and disposed of in an environmentally friendly manner. The survival rate at this stage is over 85%, which allows the fry to undergo high-temperature training, improving their survival rate in the later summer heat.

[0012] Step 4: Cooling down for seedling emergence. After 15 days of high-temperature training, the temperature is slowly lowered to room temperature, and the cooling process is completed within 6 hours.

[0013] In an optional embodiment of the present invention, step 1 further includes: before carrying out high-temperature and high-density seedling training, the farmer needs to make full preparations: first, disinfect the site with povidone-iodine or potassium permanganate solution to ensure the site is clean and hygienic and avoid the spread of germs; introduce fresh water and adjust the water quality to suit the growth of eels.

[0014] In an optional embodiment of the present invention, step 1 specifically includes: purchasing and transporting eel fry: purchasing eel fry from April to June, selecting eel fry of uniform size, weighing >10g, healthy and unharmed, and with good vitality; purchasing eel fry every morning from 6 to 8 am, using open containers made of wood or plastic for transportation, transporting eel fry to water in a ratio of 1:2, and the transportation time during the journey does not exceed 2 hours.

[0015] In an optional embodiment of the present invention, step 2 specifically includes: high-density initial screening: the transported eel fry are soaked in 1-1.5% saline solution for 5-10 minutes, disinfected, and then placed in a pre-prepared acclimation tank. The acclimation tank is 1m in size. 3 Prepare canvas pools or PVC seedling training tanks on both sides, and fill the tanks with artificial grass to provide habitats for the eels. Put 20-30 catties of eel fry into each training tank, add 4 times the amount of water, and control the temperature difference within 2℃. Conduct a preliminary screening for 24 hours to remove eel fry that were damaged during transportation or that were under great stress, which are characterized by poor nesting, staking, and low vitality. The selected eel fry can be sent to the market for sale. Damaged and stressed eel fry do not affect consumption and avoid mass mortality during high-temperature training, which would pollute the water. The screening rate at this stage is 5%-10%.

[0016] In an optional embodiment of the present invention, step 3 specifically includes: High-temperature training: After high-density initial screening, on the second day, the water temperature is slowly raised to the outdoor water temperature at the time of purchasing the eel fry plus 10°C, but the maximum temperature does not exceed 35°C. Furthermore, if the maximum temperature is below 35°C, the water temperature should be raised to 35°C after 15 days to continue training for 3-5 days to enhance the high-temperature training effect. The heating device is an air-source heat pump, with the power selected based on water consumption; the heating rate is controlled to be completed within 6 hours; and the high-temperature environment is maintained for 15 days without feeding. Dead eel fry are screened out and disposed of in an environmentally friendly manner. High temperatures also effectively kill harmful microorganisms, providing a healthier growth environment for the eels. The survival rate at this stage is over 85%.

[0017] In an optional embodiment of the present invention, step 3 further includes: water quality management: Under high temperature conditions, the metabolic rate of eels is relatively fast, and the water quality deteriorates rapidly in the early stages; ensure 5-6 water changes per day for the first 5 days, and 3-4 water changes per day for the next 10 days, draining all water from the seedling tank each time and adding fresh water; in addition, timely oxygenation of the water is necessary to maintain good water quality; after each water change for the first 5 days, add florfenicol according to the instructions to effectively treat parasitic diseases; after each water change for the next 10 days, add fermented lactic acid bacteria according to the instructions to regulate the intestinal microecology by inhibiting harmful intestinal bacteria and lowering the pH of the water to inhibit the reproduction of harmful bacteria. Farmers should regularly observe the condition of the eels, promptly identify any abnormalities, and take appropriate measures.

[0018] This invention provides a high-temperature, high-density eel seedling training device, comprising a water storage tank (1), a heating device (2), multiple seedling training tanks (3), and a sewage tank (4). The water storage tank (1) is connected to the heating device (2) through a first inlet pipe (5), the heating device (2) is connected to the multiple seedling training tanks (3) through a second inlet pipe (6), and the multiple seedling training tanks (3) are connected to the sewage tank (4) through a drain pipe (7). When the spring temperature gradually warms up, farmers can start preparing for seedling training from April to June. At this time, the eel seedlings have just recovered from hibernation. By setting a high-temperature and high-density environment through the eel seedling training device, the seedlings are trained under high temperature and high density, improving their adaptability to high-density farming in the later stage and increasing their survival rate in the summer heat.

[0019] In an optional embodiment of the present invention, the heating device (2) includes a water level layer and a heating layer located below the water level layer, wherein the heating layer and the water level layer are sealed together.

[0020] In one optional embodiment of the present invention, multiple seedling buckets (3) are arranged in two rows, and the second water inlet pipe (6) is provided with two branch pipes, the protruding nozzle structure of the two branch pipes being connected to the two rows of seedling buckets (3) respectively.

[0021] Compared with the prior art, the present invention provides a method and device for high-temperature and high-density training of eel seedlings, which has the following beneficial effects: (1) The present invention sets up a high-temperature and high-density environment, so that the seedlings are trained in high temperature and high density, which improves their adaptability to high-density farming in the later stage and improves their survival rate in summer high temperature. The method of the present invention is simple to operate and obtains a high survival rate of seedlings. (2) The present invention sets up a temperature transition period to select eels with weaker constitution, transportation damage and greater stress for sale, and then slowly raises the water temperature to carry out high-temperature training, which reduces the mortality rate of high-temperature training and reduces economic losses. The method of the present invention has low cost and good benefits. (3) The present invention sets up independent training tanks with independent water inlet and outlet, and puts the eel seedlings into different training tanks for training, which effectively avoids the spread of diseases during the training process and reduces economic losses. (4) The present invention sets up independent water inlet and outlet holes in each training tank, which successfully avoids the mutual influence of water quality between the training tanks, greatly reduces the spread of diseases and significantly improves the survival rate of the seedlings. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a flowchart illustrating a high-temperature, high-density method for hardening eel seedlings, as provided in an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of a high-temperature, high-density eel seedling training device provided in an embodiment of this application. Detailed Implementation

[0025] 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 device or functional component in this embodiment during use.

[0026] like Figure 1As shown, this embodiment of the invention provides a method for hardening eel seedlings based on high temperature and high density, including the following steps:

[0027] Step 1: Purchase eel fry from the market between April and June, preferably 1000 catties. Select eel fry that are uniform in size, healthy and unharmed, and have good vitality. Every morning, temporarily raise the selected eels in water and transport them back, and the transportation time should not exceed 2 hours.

[0028] Step 2, temporary rearing of seedlings: After being disinfected, the transported eel seedlings are placed in pre-prepared hardening tanks with a density of 1:4 eel seedlings to water and a temperature difference controlled within 2℃. A preliminary screening is conducted for 24 hours to remove eel seedlings that were damaged during transportation or that were under great stress, exhibiting signs of injury, stubble, and poor vitality. The poorly performing eel seedlings are then processed. The screening rate at this stage is 5%-10%, which allows the seedlings to undergo high-density hardening and improves their adaptability to high-density farming in the later stages.

[0029] Step 3, high-temperature training: On the second day, the water temperature is slowly raised to the outdoor water temperature when the eel fry were purchased plus 10°C. The temperature rise is controlled to be completed within 6 hours, and the high-temperature environment is maintained for 15 days. During this period, dead eel fry are screened out and disposed of in an environmentally friendly manner. The survival rate at this stage is over 85%, which allows the fry to undergo high-temperature training, improving the survival rate in the later summer high temperatures, as shown in Table 1.

[0030] Table 1 Survival rate of eel fry after high-temperature training.

[0031] time Mortality (g) Cumulative mortality (g) Cumulative survival rate (%) 1d 0 0 100 2d 600 600 99.88 3d 1450 2050 99.59 4d 1070 3120 99.376 5th 1750 4870 99.026 6d 1850 6720 98.656 7th day 2700 9420 98.116 8th 5100 14520 97.096 9d 3250 17770 96.446 10d 1250 19020 96.196 11d 500 19520 96.096 12th 100 19620 96.076 13th 0 19620 96.076 14th 0 19620 96.076 15d 0 19620 96.076

[0032] Step 4: Cooling down for seedling emergence. After 15 days of high-temperature training, the temperature is slowly lowered to room temperature, and the cooling process is completed within 6 hours.

[0033] Step 1 also includes: Preparations before acclimatization: Before conducting high-temperature and high-density acclimatization, farmers need to make full preparations: First, disinfect the site with povidone-iodine or potassium permanganate solution to ensure the site is clean and hygienic and avoid the spread of germs; introduce fresh water and adjust the water quality to suit the growth of eels.

[0034] Step 1 specifically includes: purchasing and transporting eel fry: purchasing eel fry from April to June, selecting eel fry of uniform size, weighing >10g, healthy and unharmed, and with good vitality; purchasing eel fry every morning from 6 to 8 am, using open containers made of wood or plastic for transportation, transporting eel fry to water in a ratio of 1:2, and ensuring that the transportation time does not exceed 2 hours.

[0035] Step 2 specifically includes: High-density initial screening: After the eel fry are transported back, they are soaked in 1-1.5% saline solution for 5-10 minutes. After disinfection, they are placed in a pre-prepared hardening-off tank. The hardening-off tank should be 1m in size. 3Prepare canvas pools or PVC seedling training tanks on both sides, and fill the tanks with artificial grass to provide habitats for the eels. Put 20-30 catties of eel fry into each training tank, add 4 times the amount of water, and control the temperature difference within 2℃. Conduct a preliminary screening for 24 hours to remove eel fry that were damaged during transportation or that were under great stress, which are characterized by poor nesting, staking, and low vitality. The selected eel fry can be sent to the market for sale. Damaged and stressed eel fry do not affect consumption and avoid mass mortality during high-temperature training, which would pollute the water. The screening rate at this stage is 5%-10%.

[0036] Step 3 specifically includes: High-temperature training: After high-density initial screening, on the second day, the water temperature is slowly raised to the outdoor water temperature at the time of purchasing the eel fry plus 10°C, but the maximum temperature does not exceed 35°C. The heating device is an air-source heat pump, and the power is selected according to the water consumption. The heating rate is controlled to be completed within 6 hours. The high-temperature environment is maintained for 15 days, during which no feeding is performed, and dead eel fry are screened out and disposed of in an environmentally friendly manner. High temperature can also effectively kill harmful microorganisms and provide a healthier growth environment for the eels. The survival rate at this stage is over 85%.

[0037] Step 3 also includes: Water quality management: In high-temperature environments, eels have a faster metabolic rate, and water quality deteriorates rapidly in the early stages; ensure 5-6 water changes per day for the first 5 days, and 3-4 water changes per day for the next 10 days, draining all water from the seedling tank each time and adding fresh water; in addition, timely oxygenation of the water is necessary to maintain good water quality. After each water change for the first 5 days, add florfenicol according to the instructions to effectively treat parasitic diseases; after each water change for the next 10 days, add fermented lactic acid bacteria according to the instructions to regulate the intestinal microecology by inhibiting harmful intestinal bacteria and lowering the pH of the water to inhibit the reproduction of harmful bacteria; farmers should regularly observe the condition of the eels, promptly identify any abnormalities, and take appropriate measures.

[0038] This invention creates a high-temperature, high-density environment, subjecting eel seedlings to high-temperature and high-density training, thereby improving their adaptability to later high-density farming and increasing their survival rate in summer heat. The method is simple to operate and yields a high survival rate for the seedlings. Furthermore, by setting a temperature transition period, this invention selects weaker eels, those damaged during transport, and those experiencing significant stress for sale. Then, the water temperature is slowly increased for high-temperature training, reducing mortality during this training and minimizing economic losses. This method is low-cost and highly effective.

[0039] This invention also provides a high-temperature, high-density eel fry training device. The eel fry training method described above utilizes this device for some process operations. As temperatures gradually warm in spring, farmers can begin fry training from April to June. At this time, the eel fry have just recovered from hibernation. By setting up a high-temperature, high-density environment using the fry training device, the fry undergo high-temperature and high-density training, improving their adaptability to later high-density farming and increasing their survival rate in the summer heat. This also lays a solid foundation for the healthy growth of eels throughout the year.

[0040] like Figure 2 As shown, a high-temperature, high-density eel acclimation device includes a water storage tank 1, a heating device 2, multiple acclimation tanks 3, and a drainage tank 4. The water storage tank 1 is connected to the heating device 2 via a first inlet pipe 5. The heating device 2 is connected to the multiple acclimation tanks 3 via a second inlet pipe 6. The multiple acclimation tanks 3 are connected to the drainage tank 4 via a drain pipe 7. The heating device 2 includes a water level layer and a heating layer located below the water level layer, with a sealed connection between the heating layer and the water level layer. The multiple acclimation tanks 3 are arranged in two rows. The second inlet pipe 6 has two branch pipes, and the protruding nozzle structures of the two branch pipes are respectively connected to the two rows of acclimation tanks 3.

[0041] By setting up independent training tanks with independent water inlet and outlet, eel fry can be placed in different training tanks for training, effectively avoiding the spread of diseases during the training process and reducing economic losses. This invention, by setting independent water inlet and outlet holes in each training tank, successfully avoids mutual influence of water quality between tanks, greatly reducing disease transmission and significantly improving the survival rate of the trained fry.

[0042] 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 method for acclimating eel seedlings based on high temperature and high density, characterized in that, Includes the following steps: Step 1: Purchase eel fry from the market between April and June. Select eel fry that are of uniform size, healthy, unharmed, and vigorous. Temporarily raise the selected eels in water and transport them back every morning, with the transportation time not exceeding 2 hours. Step 2, temporary rearing of seedlings: After being disinfected, the transported eel seedlings are placed in pre-prepared hardening tanks with a density of 1:4 eel seedlings to water and a temperature difference controlled within 2℃. A preliminary screening is conducted for 24 hours to remove eel seedlings that were damaged during transportation or that were under great stress, exhibiting signs of injury, stubble, and poor vitality. The poorly performing eel seedlings are then processed. The screening rate at this stage is 5%-10%, which allows the seedlings to undergo high-density hardening and improves their adaptability to high-density farming in the later stages. Step 3, high-temperature training: On the second day, slowly raise the water temperature to the outdoor water temperature when purchasing the eel fry plus 10°C. The temperature rise should be completed within 6 hours, and the high-temperature environment should be maintained for 15 days. During this period, dead eel fry should be screened out and disposed of in an environmentally friendly manner. The survival rate at this stage is over 85%, which allows the fry to undergo high-temperature training, improving their survival rate in the later summer heat. Step 4: Cooling down for seedling emergence. After 15 days of high-temperature training, the temperature is slowly lowered to room temperature, and the cooling process is completed within 6 hours. Step 3 specifically includes: High-temperature training: After high-density initial screening, on the second day, the water temperature is slowly raised to the outdoor water temperature at the time of purchasing the eel fry plus 10°C, but the maximum temperature does not exceed 35°C. In addition, if the maximum temperature is lower than 35°C, the water temperature is raised to 35°C after 15 days to continue training for 3-5 days to enhance the effect of high-temperature training; the heating device is an air-source heat pump, and the power selection is based on the water consumption; the heating rate is controlled to be completed within 6 hours; and the high-temperature environment is maintained for 15 days without feeding, and dead eel fry are screened out and disposed of in an environmentally friendly manner; high temperature can also effectively kill harmful microorganisms, providing a healthier growth environment for the eels, and the survival rate at this stage is over 85%; Step 3 also includes: Water quality management: In high-temperature environments, eels have a faster metabolic rate, and water quality deteriorates rapidly in the early stages; ensure 5-6 water changes per day for the first 5 days, and 3-4 water changes per day for the next 10 days, draining all water from the seedling tank each time and adding fresh water; in addition, timely oxygenation of the water is necessary to maintain good water quality. After each water change for the first 5 days, add florfenicol to effectively treat parasitic diseases; after each water change for the next 10 days, add fermented lactic acid bacteria according to the instructions, which regulates the intestinal microecology by inhibiting harmful intestinal bacteria and lowering the pH of the water to inhibit the reproduction of harmful bacteria; farmers should regularly observe the condition of the eels, promptly identify any abnormalities, and take appropriate measures.

2. The method for cultivating eel seedlings based on high temperature and high density according to claim 1, characterized in that, Step 1 also includes: Before carrying out high-temperature and high-density seedling training, farmers need to make full preparations: First, disinfect the site with povidone-iodine or potassium permanganate solution to ensure the site is clean and hygienic and avoid the spread of germs; introduce fresh water and adjust the water quality to suit the growth of eels.

3. The method for acclimating eel seedlings based on high temperature and high density according to claim 1, characterized in that, Step 1 specifically includes: purchasing and transporting eel fry: purchasing eel fry from April to June, selecting eel fry of uniform size, weighing >10g, healthy and unharmed, and with good vitality; purchasing eel fry every morning from 6 to 8 am, using open containers made of wood or plastic for transportation, transporting eel fry to water in a ratio of 1:2, and ensuring that the transportation time does not exceed 2 hours.

4. The method for cultivating eel seedlings based on high temperature and high density according to claim 1, characterized in that, Step 2 specifically includes: High-density initial screening: After the eel fry are transported back, they are soaked in 1-1.5% saline solution for 5-10 minutes, disinfected, and then placed in a pre-prepared hardening-off tank. The hardening-off tank should be 1m in size. 3 Prepare canvas pools or PVC seedling training tanks on both sides, and fill the tanks with artificial grass to provide habitats for the eels. Put 20-30 catties of eel fry into each training tank, add 4 times the amount of water, and control the temperature difference within 2℃. Conduct a preliminary screening for 24 hours to remove eel fry that were damaged during transportation or that were under great stress, which are characterized by poor nesting, staking, and low vitality. The selected eel fry can be sent to the market for sale. Damaged and stressed eel fry do not affect consumption and avoid mass mortality during high-temperature training, which would pollute the water. The screening rate at this stage is 5%-10%.

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