Nursery water quality requirements
During the nursery process, the water quality of the nursery shall be continuously monitored to meet the following requirements: pH value 7.8-8.4; chemical oxygen demand 1 mg/l or less: total ammonia nitrogen 0.05 mg/l or less; nitrite nitrogen 0.01 mg/l The following; dissolved oxygen 5.0 mg / liter or more; the chemical oxygen demand (COD) value of the nursery water source is preferably below 1 mg/l, and the pool should be controlled below 5 mg/l. The salinity of sea water from nauplii to shrimp is 25-32, and the salinity is adjusted as needed. The water for nursery needs to be strictly handled. The contents of this aspect have been written by others, and the relative content is relatively large. This article will not repeat them here.
Reasonable larval rearing density and feeding amount
To change the habit of over-cultivation of larvae at many shrimp farms. Should be based on the characteristics of different shrimp flexibility, generally requires the control of nauplii shrimp nauplii density of about 100,000, the control of larvae density of Penaeus vannamei is about 150,000.
Grasping the amount of feed is the key to maintaining good water quality and raising the survival rate of nursery. The reference feeding amount is (except for the unicellular algae): in the juvenile stage, artificial diets are fed 6 times/day, 0.5-1.2 g/m3 each time. During the prawn-feeding period, they were fed with diets for 6 times/day, 1.2-2.5 g/m3 each time; each prawn larvae were fed Artemia nauplii 6-20/day in 3-6 feedings. During the prawns stage, P1-P12 were fed with diets for 6 times/day, 2.5-4.0 g/m3 each, and each shrimp larvae were fed Artemia nauplii 20-100/day, divided into 3-6 shots. Hey. In addition to referring to the above-mentioned feeding amount, the feeding amount should be adjusted in time according to the actual feeding condition of the larvae and the water quality in the breeding process so as to be sufficient and without excessive waste. In addition, Artemia nauplii should be fed more to the shrimp (before P8) in the late stage of shrimp until the quantity of compound feed is reduced. This can not only control the water quality, but also cultivate high quality shrimp seedlings.
Single cell algae feeding method
1. The advantages of feeding the monocytic algae.
In the stage of zoea, if the unicellular algae is absent, the survival rate is low, the metamorphic time is long, and the water quality in the later period is difficult to control; the appropriate amount of unicellular algae in the prawn and shrimp (before P5) can enhance the vigor of the shrimp seedlings. , Make the shrimp abnormal and orderly, reduce the occurrence of disease.
2. Attentions on the feeding of single cell algae.
(1) The single-cell algae in the exponential growth period were selected for feeding. Observed with a microscope, there are no dead cells in the algae. The live algae are active and active. The cell chain length of Skeletonema is golden yellow, and the color of the algae in the pool is fresh. This kind of algae is of high quality and can be fed. On the contrary, the algae color in the cultivation pond is aging, there are agglomerates, the cell chain is broken and broken up, there is a phenomenon that the dead algae floats, and the phenomenon is that the inferior algae is toxic to the larvae and should not be fed.
(2) Feeding amount. Different larval development stages have different requirements for the amount (concentration) of unicellular algae, but not so much. If there are too many algae, they will die and die, which in turn will damage the water quality. The specific feeding amount is "a larval stage, which is fed with 3-8 times per day of single-celled algae, such as Skeletonema and Ceratophyllum, and the density is 10-15 in a seedling pool. Cells/ml; during the prawn-feeding period, single-celled algae such as Skeletonema and Chaetoceros are fed for 2-4 times per day, and the amount of larvae in the nursery pool is (3-8) 104 cells/ Milliliter; shrimps period according to the specific circumstances of algae, P1-P4 can be fed Skeletonema, Chaetoceros mongolica 2-3 times / day, each feeding so that the density in the seedling pool water (2 - 5) 104 cells/ml, algae are not fed after P5.
Pollution absorption at a proper time to prevent contamination during nursery
The juvenile larvae filter large amounts of algae, and in the micro-inflated conditions, the feces produced are accumulated together with the larvae's skin and dead individuals, providing a breeding ground for pathogens and protozoa. Therefore, it is necessary to clear it. In the stage of juvenile larvae, the fed artificial diet is less, the pool water is clearer, and piles of dirt can be seen under strong light or with a 6-12 volt illumination lamp, and the dirt is sucked out with a straw. If the pool water during the shrimp season is relatively clean, it can be sterilized once more.
The following aspects of contamination are easily overlooked in many nursery sites:
1. Self-contamination is mainly caused by the pathogens and excretions of larvae brought by the nauplii from the spawning pool. Therefore, in addition to selecting high-quality larvae, the larvae should be disinfected before lowering the pool, disinfected with 200 ml/m3 of formalin solution or 0.3 g/m3 of organic iodine solution for 30 seconds, and then used clean water for nursery. Rinse well and put it into the pool for cultivation.
2. Acid Rain Contamination The acid rain has a strong destructive effect on the stable water environment. It changes the physicochemical properties of the water, destroys the micro-ecological system in the nursery pond, causes the larvae to produce stress response, and reduces the resistance to pathogenic invasion and adverse environment. The ability to change. Once acid rain enters the pool, change the water immediately and add the water improver.
3, sand filter and filter bag to regularly clean the sand filter, often cleaning the filter bag. After the sand filter has been used for a period of time, there will be copepods or other organisms and organic matter accumulating on the surface of the pool. These bio-destructants decompose and produce toxins, which may have toxic effects on larvae. In June 2003, Zhanjiang's Xionghua shrimp farm showed sand filter was not cleaned for many months, accumulated more deaths such as copepods, cystis, and other decomposing substances, adding to the pool causing multi-chamber poisoning, empty stomach, Most of the lessons learned from death.
4. Contamination of the organisms surrounding the nursery site During the growing process, if they do not pay attention to the clearance of surrounding animals such as mice, cockroaches and pelicans, they will climb into the nursery pond to eat shrimp seed or bait. These animals will bring their own The germs brought into the nursery pool caused a large number of germs to infect the larvae. Therefore, before the start of nursery, we should do a good job in sanitation. After mixing with formaldehyde and potassium permanganate, it will be steamed and smoked for half an hour. The mosquitoes, bats and rats in the nursery will be smoked away; the killing and boating will be used again. Insecticides, such as black cyclones, kill them at the drain.
Timely and appropriate water changes
The proper amount of water change is one of the best ways to maintain and improve the water quality of the nursery ponds. When the pH of the water is too high or too low, the water color is abnormal, the ammonia nitrogen, nitrite nitrogen or hydrogen sulfide content is too high, and the larvae become ill. , must change the water treatment. The current practice is to add water at the time of juvenile larvae, add 20 centimeters of water each time or fill it up once, change the water 1-2 times depending on the situation, change the water 20%-40% each time; 1-3 times, change the water 30%-60% each time.
Use disinfectants regularly to improve the water environment
In the process of raising seedlings, regular application of potassium permanganate at a concentration of 0.2-0.5 g/m 3, formaldehyde at 3-5 ml/m 3, and chlorine dioxide at 0.01 g/m 3 have a certain effect on improving the water environment.
Rational use of beneficial microbial agents
Beneficial microbial preparations can be used as bait for shrimp larvae, and at the same time have the function of inhibiting the reproduction of harmful bacteria, decomposing organic matter, reducing ammonia nitrogen and nitrite nitrogen, and thus are widely used in shrimp rearing. After use, the water quality of the nursery was effectively improved, the pool bottom was purified, and the survival rate of larvae was generally improved. The general dosage is 3-10 ml/m3, and the specific dosage and method of use are performed according to the product specification.
During the nursery process, the water quality of the nursery shall be continuously monitored to meet the following requirements: pH value 7.8-8.4; chemical oxygen demand 1 mg/l or less: total ammonia nitrogen 0.05 mg/l or less; nitrite nitrogen 0.01 mg/l The following; dissolved oxygen 5.0 mg / liter or more; the chemical oxygen demand (COD) value of the nursery water source is preferably below 1 mg/l, and the pool should be controlled below 5 mg/l. The salinity of sea water from nauplii to shrimp is 25-32, and the salinity is adjusted as needed. The water for nursery needs to be strictly handled. The contents of this aspect have been written by others, and the relative content is relatively large. This article will not repeat them here.
Reasonable larval rearing density and feeding amount
To change the habit of over-cultivation of larvae at many shrimp farms. Should be based on the characteristics of different shrimp flexibility, generally requires the control of nauplii shrimp nauplii density of about 100,000, the control of larvae density of Penaeus vannamei is about 150,000.
Grasping the amount of feed is the key to maintaining good water quality and raising the survival rate of nursery. The reference feeding amount is (except for the unicellular algae): in the juvenile stage, artificial diets are fed 6 times/day, 0.5-1.2 g/m3 each time. During the prawn-feeding period, they were fed with diets for 6 times/day, 1.2-2.5 g/m3 each time; each prawn larvae were fed Artemia nauplii 6-20/day in 3-6 feedings. During the prawns stage, P1-P12 were fed with diets for 6 times/day, 2.5-4.0 g/m3 each, and each shrimp larvae were fed Artemia nauplii 20-100/day, divided into 3-6 shots. Hey. In addition to referring to the above-mentioned feeding amount, the feeding amount should be adjusted in time according to the actual feeding condition of the larvae and the water quality in the breeding process so as to be sufficient and without excessive waste. In addition, Artemia nauplii should be fed more to the shrimp (before P8) in the late stage of shrimp until the quantity of compound feed is reduced. This can not only control the water quality, but also cultivate high quality shrimp seedlings.
Single cell algae feeding method
1. The advantages of feeding the monocytic algae.
In the stage of zoea, if the unicellular algae is absent, the survival rate is low, the metamorphic time is long, and the water quality in the later period is difficult to control; the appropriate amount of unicellular algae in the prawn and shrimp (before P5) can enhance the vigor of the shrimp seedlings. , Make the shrimp abnormal and orderly, reduce the occurrence of disease.
2. Attentions on the feeding of single cell algae.
(1) The single-cell algae in the exponential growth period were selected for feeding. Observed with a microscope, there are no dead cells in the algae. The live algae are active and active. The cell chain length of Skeletonema is golden yellow, and the color of the algae in the pool is fresh. This kind of algae is of high quality and can be fed. On the contrary, the algae color in the cultivation pond is aging, there are agglomerates, the cell chain is broken and broken up, there is a phenomenon that the dead algae floats, and the phenomenon is that the inferior algae is toxic to the larvae and should not be fed.
(2) Feeding amount. Different larval development stages have different requirements for the amount (concentration) of unicellular algae, but not so much. If there are too many algae, they will die and die, which in turn will damage the water quality. The specific feeding amount is "a larval stage, which is fed with 3-8 times per day of single-celled algae, such as Skeletonema and Ceratophyllum, and the density is 10-15 in a seedling pool. Cells/ml; during the prawn-feeding period, single-celled algae such as Skeletonema and Chaetoceros are fed for 2-4 times per day, and the amount of larvae in the nursery pool is (3-8) 104 cells/ Milliliter; shrimps period according to the specific circumstances of algae, P1-P4 can be fed Skeletonema, Chaetoceros mongolica 2-3 times / day, each feeding so that the density in the seedling pool water (2 - 5) 104 cells/ml, algae are not fed after P5.
Pollution absorption at a proper time to prevent contamination during nursery
The juvenile larvae filter large amounts of algae, and in the micro-inflated conditions, the feces produced are accumulated together with the larvae's skin and dead individuals, providing a breeding ground for pathogens and protozoa. Therefore, it is necessary to clear it. In the stage of juvenile larvae, the fed artificial diet is less, the pool water is clearer, and piles of dirt can be seen under strong light or with a 6-12 volt illumination lamp, and the dirt is sucked out with a straw. If the pool water during the shrimp season is relatively clean, it can be sterilized once more.
The following aspects of contamination are easily overlooked in many nursery sites:
1. Self-contamination is mainly caused by the pathogens and excretions of larvae brought by the nauplii from the spawning pool. Therefore, in addition to selecting high-quality larvae, the larvae should be disinfected before lowering the pool, disinfected with 200 ml/m3 of formalin solution or 0.3 g/m3 of organic iodine solution for 30 seconds, and then used clean water for nursery. Rinse well and put it into the pool for cultivation.
2. Acid Rain Contamination The acid rain has a strong destructive effect on the stable water environment. It changes the physicochemical properties of the water, destroys the micro-ecological system in the nursery pond, causes the larvae to produce stress response, and reduces the resistance to pathogenic invasion and adverse environment. The ability to change. Once acid rain enters the pool, change the water immediately and add the water improver.
3, sand filter and filter bag to regularly clean the sand filter, often cleaning the filter bag. After the sand filter has been used for a period of time, there will be copepods or other organisms and organic matter accumulating on the surface of the pool. These bio-destructants decompose and produce toxins, which may have toxic effects on larvae. In June 2003, Zhanjiang's Xionghua shrimp farm showed sand filter was not cleaned for many months, accumulated more deaths such as copepods, cystis, and other decomposing substances, adding to the pool causing multi-chamber poisoning, empty stomach, Most of the lessons learned from death.
4. Contamination of the organisms surrounding the nursery site During the growing process, if they do not pay attention to the clearance of surrounding animals such as mice, cockroaches and pelicans, they will climb into the nursery pond to eat shrimp seed or bait. These animals will bring their own The germs brought into the nursery pool caused a large number of germs to infect the larvae. Therefore, before the start of nursery, we should do a good job in sanitation. After mixing with formaldehyde and potassium permanganate, it will be steamed and smoked for half an hour. The mosquitoes, bats and rats in the nursery will be smoked away; the killing and boating will be used again. Insecticides, such as black cyclones, kill them at the drain.
Timely and appropriate water changes
The proper amount of water change is one of the best ways to maintain and improve the water quality of the nursery ponds. When the pH of the water is too high or too low, the water color is abnormal, the ammonia nitrogen, nitrite nitrogen or hydrogen sulfide content is too high, and the larvae become ill. , must change the water treatment. The current practice is to add water at the time of juvenile larvae, add 20 centimeters of water each time or fill it up once, change the water 1-2 times depending on the situation, change the water 20%-40% each time; 1-3 times, change the water 30%-60% each time.
Use disinfectants regularly to improve the water environment
In the process of raising seedlings, regular application of potassium permanganate at a concentration of 0.2-0.5 g/m 3, formaldehyde at 3-5 ml/m 3, and chlorine dioxide at 0.01 g/m 3 have a certain effect on improving the water environment.
Rational use of beneficial microbial agents
Beneficial microbial preparations can be used as bait for shrimp larvae, and at the same time have the function of inhibiting the reproduction of harmful bacteria, decomposing organic matter, reducing ammonia nitrogen and nitrite nitrogen, and thus are widely used in shrimp rearing. After use, the water quality of the nursery was effectively improved, the pool bottom was purified, and the survival rate of larvae was generally improved. The general dosage is 3-10 ml/m3, and the specific dosage and method of use are performed according to the product specification.
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