Cultivation Techniques of Penaeus vannamei
2018-05-25 01:41:20
I. Nursery construction
1. The geographic conditions of the construction site should be examined before the site construction, test the water quality, and carefully select the nursery site. The specific requirements are: (1) The site should be on the inner side of sheltered bays or highlands, facing south to the south, and the surrounding water quality should be clean and free of industrial and urban pollution. (2) The salinity of seawater is not less than 23, and the pH is stable at around 8.0. (3) The nursery should be close to natural broodstock production areas. (4) electricity, water, convenient transportation, vehicles and boats can be reached directly, fresh water supply is abundant.
2. The layout of nursery sites The main facilities include nursery rooms, plant bait culture ponds, animal feed (Artemia) breeding rooms, broodstock overwintering pools, spawning pools, and gas supply, heating, water supply, and power supply systems. For artificial breeding of seawater in the estuary area, it is necessary to construct a brine storage tank, a seawater distribution room, and a seawater purification device.
Second, nursery basic facilities
1. Nursery Room The shrimp breeding seedlings are susceptible to cold air in the early stage, and are susceptible to the Meiyu in the south and later stages. Therefore, the seedling nursery room is required for indoor nursery. The structure and materials of the nursery room should be light-transmitting, heat-insulating and wind-resistant, and should be durable. The civil structure is generally used. The top can be covered with glass or FRP wave tiles, and the glass windows are installed around. If glass fibre reinforced corrugated tiles are used to cover the roof, the light transmittance is required to be 60% to 70%. If glass sunroofs are used, curtains should be provided to adjust light.
2. Breeding pond nursery pond should be reasonable layout, easy operation and durability. Nursery ponds are seated, semi-embedded or buried.
Nursery ponds should be large or small in order to adapt to changes in the source and quantity of broodstock, which will help regulate the amount of spawning and shrimp production. When designing a nursery pond, the effective area of ​​the nursery room should be used to the maximum extent. The pedestrian aisle should not be too wide and should be within 1 meter.
The shape of the pool is rectangular, and the operation is convenient. The depth of the pool is 1.5 meters to 2 meters. The wall of the pool can be filled with reinforced concrete, brick or stone can also be used, and cement can be applied externally, requiring no leakage or cracking. Usually 100 tons of water body of the pool, wall brick wall thickness of 24 cm, the pool wall thickness of 36 cm, the top of the pool wall is appropriately widened in order to walk and operate. The water supply and inflation pipelines should be installed. It is better not to occupy the top of the pool wall to facilitate operations.
3. Feeding ponds The prawn larvae feed bio-cultivating pools include monilia culture ponds, rotifer culture ponds, and artemia hatching ponds. The size and number of these should be determined by the number of nursery stocks. The use of artificial bait and Artemia larvae as the main nursery, can not build or less built bait biological culture pool, if the use of pure breeding algae and rotifer breeding methods, you need to have a certain percentage of the bait pool, generally for the nursery water body 2 to 3 times (rotor pool can be earthen pond). The volumetric ratio of the nursery pond, the plant food culture pond and the Artemia hatching pond was 5:1:5 or 10:1:1. At present, shrimp rearing has tended to use non-living baits instead of live bait as far as possible, so as to save the funds for constructing food baits and the labor and materials needed to cultivate bait organisms. Many nursery units use soy milk and egg yolks or cultivate large numbers of rotifers to replace expensive Artemia eggs to reduce the cost of nursery. To sum up, the bait combinations used in nursery are often of the following types: (1) Monilia → Rotifera → Artemia larvae; (2) Monoptera (or micro-food) → Artemia larvae; (3) Soybean milk → Egg yolk → Artemia larvae.
The productive cultivation of monocytic algae uses tile pools. Each pool of 2 square meters to 10 square meters, the pool depth of 0.8 meters, the bottom of the pool and a distance of 20 cm from the bottom of the pool set a drainage hole. In order to prevent rain, heat and light adjustment, the bait pond should be built indoors. The roof should be made of light-transmissive material. The sunny daylight intensity is 10,000-meter candle to 20,000-meter candle. In order to prevent contamination between the pools, a room can be divided into several units. The animal and vegetable food ponds should be constructed separately to avoid contamination. Rotifer cultivating pools can be controlled by glass fiber reinforced plastic tanks or concrete tanks for temperature control and aeration. When expanded to the scale of production, outdoor land is generally used.
Artemia hatchery pools can be cement pools or glass steel tanks. Cement pool is generally 5 cubic meters to 10 cubic meters, pot-shaped bottom, at the bottom and from the bottom of the pool 10 cm to 20 cm at each set a drainage hole for easy drainage and collection Artemia nauplii. Artemia hatching tanks are equipped with gas lift tubes, transparent windows and bottom cones, which can prevent the accumulation of Artemia eggs, but also facilitate the separation of larvae and egg shells. Incubation should be carried out during the incubation process, heating with an electric heating rod, and a planned control of the amount and time of incubation.
4. Winter of broodstock overwintering pool The wintering mode of broodstock differs from region to region. In the southern part of Fujian, the outdoor pool can be used for winter; in the south of Zhejiang, the winter in the indoor pool with better insulation conditions; and in the north of Jiangsu, the indoor pool with warming conditions is required to overwinter. When wintering indoors, there are greenhouses, brick walls, and double-glazed windows with good insulation properties, and the indoor light is controlled at 500 meters. The wintering pond is divided into several outlets, usually 20 to 50 square meters per pool. It is better to use a long-shaped pool to remove the residual bait and feces. The pool depth is 1.2 to 1.5 meters, and the bottom of the pool is 10 to 15 meters. Centimeter diameter drainage hole. In order to prevent the broodstock from hitting the wall when jumping, hang a loop of mesh within 10 cm from the pool wall.
5. Water Supply System The system includes a reservoir, a sedimentation tank, a high water tower, a sand filter, a water pump, and an intake and drainage pipeline. (1) Reservoir Water for nursery seedlings It is best to take clean fresh seawater or seawater wells in the sea area. If conditions are limited, a tidal-type reservoir can be built. The size of the pool can be used to satisfy one flood season, and can also be replaced by a relatively clean shrimp pond. The general area is about 10 acres, and the seawater is precipitated for 24 hours to 48 hours. You can use it later. (2) The sedimentation tank is calculated according to the total storage volume equal to the total water for the nursery. To ensure daily water supply, the sedimentation tank shall be built with two or two separated to be used interchangeably. The top of the tank shall be covered or shaded by scaffolding. (3) The sand filter culture bait organisms and broodstock spawning water for hatching must be sand filtered to remove haze from enemy organisms and seawater. The sand filter is generally built at the highest point. The size of the sand filter should be determined by the water quality of the sea area and the amount of water used for nursery. It is better to build two filters for rotation. The sand filter structure is a device made up of pebbles, coarse sand, and fine sand of different sizes and has the functions of trapping, sedimentation, and coagulation. The filter membrane formed by the agglomeration action can prevent organic debris from passing through the sand layer and is more effective than mechanical filtration, and can also play a role in purifying water quality. (4) Water pump and pipeline The water pump should be selected according to the requirements of suction and lift. Generally, centrifugal pumps are used more often. The size of the pump should be determined according to the size of the water in the nursery. Pipes, brass pipes, galvanized pipes, and rubber hoses are prohibited for water pipes. Hard plastic pipes (PVC pipes) and cement pipes that are harmless to larvae should be used. Polypropylene tubes, although non-toxic, are easily deformed and broken and should be maintained during use.
6. The inflation of inflatable equipment has many aspects for nursery and is an indispensable condition for industrialized nursery. The aeration system includes an inflator, an air supply duct, a diffuser or a diffuser. (1) Roots blowers and air compressors are commonly used for inflators. Mass production uses more Roots blowers. It has the advantages of large air volume, stable pressure, gas-free oil and power saving. During the nursery period, 1% to 1.5% of the water should be injected into the water within one minute. Therefore, the specifications of the blower should be based on the total water body of the nursery, and the wind pressure is related to the depth of water. For a nursery pond with a water depth of 1.5 meters or more, a blower with a wind pressure of 0.35 kg to 0.5 kg per square centimeter should be used; the depth of water is less than 1 meter. A 0.2 kg blower per square centimeter of air pressure can be used. In order to ensure the normal operation of the nursery work, the inflator should be equipped with more than two for standby and rotation. (2) The air supply pipe is divided into the main pipe, branch pipe and branch pipe. The main pipe is connected with a blower, and the rigid plastic pipe with a diameter of 12 cm to 18 cm is usually used; the pipe diameter is 6 cm to 9 cm, and it is also a rigid plastic pipe; the branch pipe is a plastic hose with a diameter of 0.6 cm to 1.0 cm, and the air is connected to the next stone. (3) Diffusion stones are generally 5 cm to 10 cm in length and 3 cm to 4 cm in diameter. They are mostly made of abrasive wheels made of 200-400 emery. In the nursery pond, it is advisable to place 1 gas stone per square meter of the bottom of the pool, and a switch for adjusting the gas volume is provided on the gas supply pipeline. Diffusion tube is a plastic tube, diameter 20 mm, every 2 cm drilled a small hole, aperture 0.8 mm, arranged in a straight line, the distribution of the diffuser can be considered according to the pool size and pool shape, the distance between the diffuser tube is about 3 meters, and Nursery ponds are arranged vertically and can be fixed at a distance of 3 cm to 5 cm from the bottom of the pool.
7. Temperature control facilities Temperature control is an important measure for shrimp rearing. The current method of warming is:
(1) Boiler warming The northern nursery is heated by a boiler, and the hot air heats the pool water through the pipes in the pool. The heating pipes are arranged in an annular shape, and the pipes are made of stainless steel pipes. If cast steel pipes are used, in order to prevent the pipes from rusting, epoxy resin shall be applied and wrapped with glass fiber cloth. The heating pipe should be set up to facilitate installation and maintenance. Generally, the distance from the wall of the pool to the bottom of the pool is 30 centimeters. Each tank is individually provided with a valve for controlling the ventilation. A temperature control device can also be used to control the temperature. (2) The electric heating can be heated by electric heating rods (titanium rods, stainless steel rods), electric heating beds, etc. Under water heating, it can also be heated by electric heating plates, etc. Various heaters can be controlled by the controller to adjust the temperature. In addition, the use of solar energy, underground heat sources and plant waste heat. It is also possible to use a heating device to warm the air in the nursery room and gradually increase the water temperature in the nursery.
8. The power supply device can not be interrupted during seedling raising. It should be equipped with a generator and set up special personnel to manage it.
9. Nursery tools In addition to supporting facilities for shrimp seedlings, certain instruments and necessary nursery tools are needed to make them easier to use. There are many kinds of nursery tools, such as canvas buckets for transporting broodstock, holding boxes for raising broodstock, cages and cage racks for broodstock hatching, samplers for checking larvae, and drainage nets for changing water. Siphons, plastic barrels, water spoons, dip nets, scrubbing boards, bamboo brooms, etc. These tools must be disinfected before use, dedicated pools, and prevent pollution. The nursery tools are not new and are better than the old ones. The new ones are untreated and sometimes harmful, especially wooden (such as cage frames) and rubber products (rubber pipes) that are not soaked for long periods of time before use. It will poison the larvae.
In order to remove all the factors that may cause water pollution and poisoning, attention should be paid in the use of: (1) New rubber tubes, vinyl chloride products, and wooden net racks should not be easily brought into contact with the nursery water before thoroughly soaking. (2) Tools made of metal, especially copper, zinc, and chrome-plated products, will have a large number of toxic ions leaching out after entering the water, causing death or deformity of the larvae. They must be disabled; (3) Any tools must be cleaned and disinfected before use. A special disinfection tank can be set to disinfect with the formalin of 25010-6, and the tool should be washed immediately after use. (4) If the conditions are right, the tools should be dedicated to the pool, especially the sampler, which is the easiest medium for disease transmission. It is forbidden to string pool.
3. Treatment of nursery water The treatment of nursery water includes adjustment of water temperature, salinity and pH, elimination or reduction of excess metal ions in the water, and prevention and removal of enemy pests in the water. Seawater treatment usually uses methods such as sedimentation, filtration, replacement of water, aeration, and delivery of ethylenediaminetetraacetic acid sodium salt (EDTA), and if necessary seawater disinfection is also required. In general, the above method alone is less effective, and adopting comprehensive measures can achieve better results. The filtration and seawater dechlorination methods are briefly described as follows:
1.Simple filtration uses screen mesh (150 mesh for early seedling and 80 mesh for later) filtration to remove most of the enemy pests and suspended debris. This method cannot eliminate pathogenic bacteria and ciliates.
2. Sand filter The sand filter used for filtering seawater is more clean than the sieve filter. The sedimentation of the sand layer can prevent the passage of microorganisms and organic debris through the sand layer. However, if the sand layer is not washed frequently, the filtered organic matter will be decomposed, and toxic substances will be produced and harmful to the shrimp larvae.
3. Seawater disinfection (dechlorination) Dechlorination of precipitated seawater is a more thorough method that eliminates the effects of predators and diseases.
Dechlorination can directly pass chlorine into the precipitated seawater (2 mg per liter of seawater) and dechlorinate it before use. Sodium hypochlorite or bleach may also be placed in water.
The method for disinfecting seawater with sodium hypochlorite is to add 250 ml of a 8% sodium hypochlorite solution per cubic meter of precipitated seawater (allow the concentration of available chlorine in the water to reach 2010-6). After 6 hours to 8 hours, each In cubic meters of water, 35 grams of sodium thiosulfate was added to neutralize residual chlorine.
When using sodium hypochlorite, it should be noted that the amount of drug should be based on the available chlorine content. If the chlorine content is 8% sodium hypochlorite (liquid) effective dosage is 250 ml per cubic meter of water; if the sodium hypochlorite content is 5.25%, the dosage should be 381 ml, so the effective chlorine concentration is 2010-6.
Commonly used bleaching agents to disinfect seawater, nursery tools and containers. The chlorine content of the general commercial bleaching powder is 25% to 35% (60% to 70% of the chlorine content of bleached fines), but the available chlorine is very unstable. After exposure to air, it is often combined with carbon dioxide and water and rapidly decomposes. Escape. In the sun (ultraviolet) and high temperature conditions, the chlorine content of the bleach will also decrease. If the product is left unattended for a long time or if it is stored improperly, it is easy to fail. Therefore, determine the available chlorine content before using the bleaching powder. The current simpler and more practical method is to use a blue ink titration method. The procedure is: (1) Weigh 5 grams of the bleaching powder (or bleaching agent) to be tested and place it in a mortar. (2) Add cold boiled water (do not use tap water containing chlorine), ground the bleaching powder thoroughly and add water to 100 ml. (3) After the mixture is clarified, a certain amount of the supernatant is aspirated with a cleaned quantitative pipette or a medical syringe, 38 drops are dropped into the white porcelain bowl, and the number of milliliters of drops is counted, and each is obtained. Drop the supernatant in ml. (4) Take another pipette (or syringe), draw blue ink that has not been used (Beijing and Hero cards are available), titrate it into the white porcelain bowl, stir while dripping, and the blue ink is very soon Change from blue to brown, and achromatism. Continue to titrate and a steady blue-green color appears. Record the amount of blue ink consumed in the titration. (5) Substitute the obtained blue ink consumption and the number of milliliters of each supernatant in the following formula, which is the required effective chlorine content: the available chlorine content of the bleach (%) = the amount of milliliters of blue ink consumed during the titration / (per Dilute the supernatant of the bleaching solution in ml of 100).
1. The geographic conditions of the construction site should be examined before the site construction, test the water quality, and carefully select the nursery site. The specific requirements are: (1) The site should be on the inner side of sheltered bays or highlands, facing south to the south, and the surrounding water quality should be clean and free of industrial and urban pollution. (2) The salinity of seawater is not less than 23, and the pH is stable at around 8.0. (3) The nursery should be close to natural broodstock production areas. (4) electricity, water, convenient transportation, vehicles and boats can be reached directly, fresh water supply is abundant.
2. The layout of nursery sites The main facilities include nursery rooms, plant bait culture ponds, animal feed (Artemia) breeding rooms, broodstock overwintering pools, spawning pools, and gas supply, heating, water supply, and power supply systems. For artificial breeding of seawater in the estuary area, it is necessary to construct a brine storage tank, a seawater distribution room, and a seawater purification device.
Second, nursery basic facilities
1. Nursery Room The shrimp breeding seedlings are susceptible to cold air in the early stage, and are susceptible to the Meiyu in the south and later stages. Therefore, the seedling nursery room is required for indoor nursery. The structure and materials of the nursery room should be light-transmitting, heat-insulating and wind-resistant, and should be durable. The civil structure is generally used. The top can be covered with glass or FRP wave tiles, and the glass windows are installed around. If glass fibre reinforced corrugated tiles are used to cover the roof, the light transmittance is required to be 60% to 70%. If glass sunroofs are used, curtains should be provided to adjust light.
2. Breeding pond nursery pond should be reasonable layout, easy operation and durability. Nursery ponds are seated, semi-embedded or buried.
Nursery ponds should be large or small in order to adapt to changes in the source and quantity of broodstock, which will help regulate the amount of spawning and shrimp production. When designing a nursery pond, the effective area of ​​the nursery room should be used to the maximum extent. The pedestrian aisle should not be too wide and should be within 1 meter.
The shape of the pool is rectangular, and the operation is convenient. The depth of the pool is 1.5 meters to 2 meters. The wall of the pool can be filled with reinforced concrete, brick or stone can also be used, and cement can be applied externally, requiring no leakage or cracking. Usually 100 tons of water body of the pool, wall brick wall thickness of 24 cm, the pool wall thickness of 36 cm, the top of the pool wall is appropriately widened in order to walk and operate. The water supply and inflation pipelines should be installed. It is better not to occupy the top of the pool wall to facilitate operations.
3. Feeding ponds The prawn larvae feed bio-cultivating pools include monilia culture ponds, rotifer culture ponds, and artemia hatching ponds. The size and number of these should be determined by the number of nursery stocks. The use of artificial bait and Artemia larvae as the main nursery, can not build or less built bait biological culture pool, if the use of pure breeding algae and rotifer breeding methods, you need to have a certain percentage of the bait pool, generally for the nursery water body 2 to 3 times (rotor pool can be earthen pond). The volumetric ratio of the nursery pond, the plant food culture pond and the Artemia hatching pond was 5:1:5 or 10:1:1. At present, shrimp rearing has tended to use non-living baits instead of live bait as far as possible, so as to save the funds for constructing food baits and the labor and materials needed to cultivate bait organisms. Many nursery units use soy milk and egg yolks or cultivate large numbers of rotifers to replace expensive Artemia eggs to reduce the cost of nursery. To sum up, the bait combinations used in nursery are often of the following types: (1) Monilia → Rotifera → Artemia larvae; (2) Monoptera (or micro-food) → Artemia larvae; (3) Soybean milk → Egg yolk → Artemia larvae.
The productive cultivation of monocytic algae uses tile pools. Each pool of 2 square meters to 10 square meters, the pool depth of 0.8 meters, the bottom of the pool and a distance of 20 cm from the bottom of the pool set a drainage hole. In order to prevent rain, heat and light adjustment, the bait pond should be built indoors. The roof should be made of light-transmissive material. The sunny daylight intensity is 10,000-meter candle to 20,000-meter candle. In order to prevent contamination between the pools, a room can be divided into several units. The animal and vegetable food ponds should be constructed separately to avoid contamination. Rotifer cultivating pools can be controlled by glass fiber reinforced plastic tanks or concrete tanks for temperature control and aeration. When expanded to the scale of production, outdoor land is generally used.
Artemia hatchery pools can be cement pools or glass steel tanks. Cement pool is generally 5 cubic meters to 10 cubic meters, pot-shaped bottom, at the bottom and from the bottom of the pool 10 cm to 20 cm at each set a drainage hole for easy drainage and collection Artemia nauplii. Artemia hatching tanks are equipped with gas lift tubes, transparent windows and bottom cones, which can prevent the accumulation of Artemia eggs, but also facilitate the separation of larvae and egg shells. Incubation should be carried out during the incubation process, heating with an electric heating rod, and a planned control of the amount and time of incubation.
4. Winter of broodstock overwintering pool The wintering mode of broodstock differs from region to region. In the southern part of Fujian, the outdoor pool can be used for winter; in the south of Zhejiang, the winter in the indoor pool with better insulation conditions; and in the north of Jiangsu, the indoor pool with warming conditions is required to overwinter. When wintering indoors, there are greenhouses, brick walls, and double-glazed windows with good insulation properties, and the indoor light is controlled at 500 meters. The wintering pond is divided into several outlets, usually 20 to 50 square meters per pool. It is better to use a long-shaped pool to remove the residual bait and feces. The pool depth is 1.2 to 1.5 meters, and the bottom of the pool is 10 to 15 meters. Centimeter diameter drainage hole. In order to prevent the broodstock from hitting the wall when jumping, hang a loop of mesh within 10 cm from the pool wall.
5. Water Supply System The system includes a reservoir, a sedimentation tank, a high water tower, a sand filter, a water pump, and an intake and drainage pipeline. (1) Reservoir Water for nursery seedlings It is best to take clean fresh seawater or seawater wells in the sea area. If conditions are limited, a tidal-type reservoir can be built. The size of the pool can be used to satisfy one flood season, and can also be replaced by a relatively clean shrimp pond. The general area is about 10 acres, and the seawater is precipitated for 24 hours to 48 hours. You can use it later. (2) The sedimentation tank is calculated according to the total storage volume equal to the total water for the nursery. To ensure daily water supply, the sedimentation tank shall be built with two or two separated to be used interchangeably. The top of the tank shall be covered or shaded by scaffolding. (3) The sand filter culture bait organisms and broodstock spawning water for hatching must be sand filtered to remove haze from enemy organisms and seawater. The sand filter is generally built at the highest point. The size of the sand filter should be determined by the water quality of the sea area and the amount of water used for nursery. It is better to build two filters for rotation. The sand filter structure is a device made up of pebbles, coarse sand, and fine sand of different sizes and has the functions of trapping, sedimentation, and coagulation. The filter membrane formed by the agglomeration action can prevent organic debris from passing through the sand layer and is more effective than mechanical filtration, and can also play a role in purifying water quality. (4) Water pump and pipeline The water pump should be selected according to the requirements of suction and lift. Generally, centrifugal pumps are used more often. The size of the pump should be determined according to the size of the water in the nursery. Pipes, brass pipes, galvanized pipes, and rubber hoses are prohibited for water pipes. Hard plastic pipes (PVC pipes) and cement pipes that are harmless to larvae should be used. Polypropylene tubes, although non-toxic, are easily deformed and broken and should be maintained during use.
6. The inflation of inflatable equipment has many aspects for nursery and is an indispensable condition for industrialized nursery. The aeration system includes an inflator, an air supply duct, a diffuser or a diffuser. (1) Roots blowers and air compressors are commonly used for inflators. Mass production uses more Roots blowers. It has the advantages of large air volume, stable pressure, gas-free oil and power saving. During the nursery period, 1% to 1.5% of the water should be injected into the water within one minute. Therefore, the specifications of the blower should be based on the total water body of the nursery, and the wind pressure is related to the depth of water. For a nursery pond with a water depth of 1.5 meters or more, a blower with a wind pressure of 0.35 kg to 0.5 kg per square centimeter should be used; the depth of water is less than 1 meter. A 0.2 kg blower per square centimeter of air pressure can be used. In order to ensure the normal operation of the nursery work, the inflator should be equipped with more than two for standby and rotation. (2) The air supply pipe is divided into the main pipe, branch pipe and branch pipe. The main pipe is connected with a blower, and the rigid plastic pipe with a diameter of 12 cm to 18 cm is usually used; the pipe diameter is 6 cm to 9 cm, and it is also a rigid plastic pipe; the branch pipe is a plastic hose with a diameter of 0.6 cm to 1.0 cm, and the air is connected to the next stone. (3) Diffusion stones are generally 5 cm to 10 cm in length and 3 cm to 4 cm in diameter. They are mostly made of abrasive wheels made of 200-400 emery. In the nursery pond, it is advisable to place 1 gas stone per square meter of the bottom of the pool, and a switch for adjusting the gas volume is provided on the gas supply pipeline. Diffusion tube is a plastic tube, diameter 20 mm, every 2 cm drilled a small hole, aperture 0.8 mm, arranged in a straight line, the distribution of the diffuser can be considered according to the pool size and pool shape, the distance between the diffuser tube is about 3 meters, and Nursery ponds are arranged vertically and can be fixed at a distance of 3 cm to 5 cm from the bottom of the pool.
7. Temperature control facilities Temperature control is an important measure for shrimp rearing. The current method of warming is:
(1) Boiler warming The northern nursery is heated by a boiler, and the hot air heats the pool water through the pipes in the pool. The heating pipes are arranged in an annular shape, and the pipes are made of stainless steel pipes. If cast steel pipes are used, in order to prevent the pipes from rusting, epoxy resin shall be applied and wrapped with glass fiber cloth. The heating pipe should be set up to facilitate installation and maintenance. Generally, the distance from the wall of the pool to the bottom of the pool is 30 centimeters. Each tank is individually provided with a valve for controlling the ventilation. A temperature control device can also be used to control the temperature. (2) The electric heating can be heated by electric heating rods (titanium rods, stainless steel rods), electric heating beds, etc. Under water heating, it can also be heated by electric heating plates, etc. Various heaters can be controlled by the controller to adjust the temperature. In addition, the use of solar energy, underground heat sources and plant waste heat. It is also possible to use a heating device to warm the air in the nursery room and gradually increase the water temperature in the nursery.
8. The power supply device can not be interrupted during seedling raising. It should be equipped with a generator and set up special personnel to manage it.
9. Nursery tools In addition to supporting facilities for shrimp seedlings, certain instruments and necessary nursery tools are needed to make them easier to use. There are many kinds of nursery tools, such as canvas buckets for transporting broodstock, holding boxes for raising broodstock, cages and cage racks for broodstock hatching, samplers for checking larvae, and drainage nets for changing water. Siphons, plastic barrels, water spoons, dip nets, scrubbing boards, bamboo brooms, etc. These tools must be disinfected before use, dedicated pools, and prevent pollution. The nursery tools are not new and are better than the old ones. The new ones are untreated and sometimes harmful, especially wooden (such as cage frames) and rubber products (rubber pipes) that are not soaked for long periods of time before use. It will poison the larvae.
In order to remove all the factors that may cause water pollution and poisoning, attention should be paid in the use of: (1) New rubber tubes, vinyl chloride products, and wooden net racks should not be easily brought into contact with the nursery water before thoroughly soaking. (2) Tools made of metal, especially copper, zinc, and chrome-plated products, will have a large number of toxic ions leaching out after entering the water, causing death or deformity of the larvae. They must be disabled; (3) Any tools must be cleaned and disinfected before use. A special disinfection tank can be set to disinfect with the formalin of 25010-6, and the tool should be washed immediately after use. (4) If the conditions are right, the tools should be dedicated to the pool, especially the sampler, which is the easiest medium for disease transmission. It is forbidden to string pool.
3. Treatment of nursery water The treatment of nursery water includes adjustment of water temperature, salinity and pH, elimination or reduction of excess metal ions in the water, and prevention and removal of enemy pests in the water. Seawater treatment usually uses methods such as sedimentation, filtration, replacement of water, aeration, and delivery of ethylenediaminetetraacetic acid sodium salt (EDTA), and if necessary seawater disinfection is also required. In general, the above method alone is less effective, and adopting comprehensive measures can achieve better results. The filtration and seawater dechlorination methods are briefly described as follows:
1.Simple filtration uses screen mesh (150 mesh for early seedling and 80 mesh for later) filtration to remove most of the enemy pests and suspended debris. This method cannot eliminate pathogenic bacteria and ciliates.
2. Sand filter The sand filter used for filtering seawater is more clean than the sieve filter. The sedimentation of the sand layer can prevent the passage of microorganisms and organic debris through the sand layer. However, if the sand layer is not washed frequently, the filtered organic matter will be decomposed, and toxic substances will be produced and harmful to the shrimp larvae.
3. Seawater disinfection (dechlorination) Dechlorination of precipitated seawater is a more thorough method that eliminates the effects of predators and diseases.
Dechlorination can directly pass chlorine into the precipitated seawater (2 mg per liter of seawater) and dechlorinate it before use. Sodium hypochlorite or bleach may also be placed in water.
The method for disinfecting seawater with sodium hypochlorite is to add 250 ml of a 8% sodium hypochlorite solution per cubic meter of precipitated seawater (allow the concentration of available chlorine in the water to reach 2010-6). After 6 hours to 8 hours, each In cubic meters of water, 35 grams of sodium thiosulfate was added to neutralize residual chlorine.
When using sodium hypochlorite, it should be noted that the amount of drug should be based on the available chlorine content. If the chlorine content is 8% sodium hypochlorite (liquid) effective dosage is 250 ml per cubic meter of water; if the sodium hypochlorite content is 5.25%, the dosage should be 381 ml, so the effective chlorine concentration is 2010-6.
Commonly used bleaching agents to disinfect seawater, nursery tools and containers. The chlorine content of the general commercial bleaching powder is 25% to 35% (60% to 70% of the chlorine content of bleached fines), but the available chlorine is very unstable. After exposure to air, it is often combined with carbon dioxide and water and rapidly decomposes. Escape. In the sun (ultraviolet) and high temperature conditions, the chlorine content of the bleach will also decrease. If the product is left unattended for a long time or if it is stored improperly, it is easy to fail. Therefore, determine the available chlorine content before using the bleaching powder. The current simpler and more practical method is to use a blue ink titration method. The procedure is: (1) Weigh 5 grams of the bleaching powder (or bleaching agent) to be tested and place it in a mortar. (2) Add cold boiled water (do not use tap water containing chlorine), ground the bleaching powder thoroughly and add water to 100 ml. (3) After the mixture is clarified, a certain amount of the supernatant is aspirated with a cleaned quantitative pipette or a medical syringe, 38 drops are dropped into the white porcelain bowl, and the number of milliliters of drops is counted, and each is obtained. Drop the supernatant in ml. (4) Take another pipette (or syringe), draw blue ink that has not been used (Beijing and Hero cards are available), titrate it into the white porcelain bowl, stir while dripping, and the blue ink is very soon Change from blue to brown, and achromatism. Continue to titrate and a steady blue-green color appears. Record the amount of blue ink consumed in the titration. (5) Substitute the obtained blue ink consumption and the number of milliliters of each supernatant in the following formula, which is the required effective chlorine content: the available chlorine content of the bleach (%) = the amount of milliliters of blue ink consumed during the titration / (per Dilute the supernatant of the bleaching solution in ml of 100).