The rotifer is an open bait for fry. Propagation of rotifers directly in ponds is the key to solve the problem of opening feeds for fry and reduce the production cost and improve the survival rate of fry. The specific method for growing rotifers in Tongtang Pond is as follows.
Fry ponds 15 days before the lower pond clear pond, after the disappearance of medicinal properties 50 to 60 cm. Immediately apply organic fertilizer to the pond to cultivate plankton. This method of breeding fry is called "fat pool." The fertilizer applied before the fry in the pond can be adapted to the local conditions. Generally, human excrement, chicken excrement, pig excrement, and cattle and horse excrement can also be used as fresh and perishable grasses. Fertilization methods used compost in the past. The amount of fertilizer used per mu was larger. Generally, the amount of manure was 200-250 kg per mu, and green manure was 300-400 kg. If the quality of grass was poor or the dosage was increased. In order to speed up fertilizer and water application of inorganic fertilizers, generally 4 kg of nitrogen fertilizer (ammonium sulfate, urea, etc.) and 4 kg of phosphate fertilizer (superphosphate) are applied per acre. The application of inorganic fertilizer needs Quanchiposa. Composting is to put the fertilizer in a shallow area of ​​sunny water, close to the water injection port, but away from the net position where it will go out of the pool. Fertilizers should be completely submerged in water to speed up decomposition of fertilizers. And it should be turned once every two days and three days in order to facilitate the diffusion of fertilizers into the water to improve fertilizer efficiency.
It is very important to cultivate the suitable feed for the fish pond Xiatang to master the fertilization time. After the fertilization, the plankton--the rotifers form the peak when the pond can ensure that there are enough food organisms in the fry. If the fry pond is too early or too late, the rotifer biomass does not reach the peak or the peak has passed. Fry biological shortage of fry will directly affect the survival rate and growth rate of fry. After fertilization in ponds, the peak of all kinds of zooplankton formation is: protozoa, rotifers, clafts, and copepods are the first to form peaks. In this process, the requirements for changes in the size of the fish from the pond to the summer flower pond are: rotifers and protozoa → small horns → large cladocera → copepods, which form a peak with the pond zooplankton The order is the same. The timely application of fertilizer in the pond can make good use of the consistency of the two, so that the rotifer peak appears well under the fish pond. Not only does the fish in the pond have enough palatability food, but it can also be developed in various development stages. Rich palatability feed. Therefore, the timely application of base fertilizer and fish seedlings is the key to raising fish fry.
The number of rotifers and their peak time are closely related to the number of resting eggs and the water temperature of rotifers. For example, if there is thick silt and strong water retention at the end of the pond, and a lot of organic fertilizer is applied to the pond, then there will be more dormant eggs in the silt, while in the newly opened pond or sandy bottom, the leakage is serious or the silt is thick but salt In higher ponds, rotifers have few resting eggs. The rotifer dormancy eggs are widely distributed in silt layers of different depths, gradually decreasing from the surface to the bottom and presenting a “Vâ€-shaped distribution, with the surface layer (0 to 5 cm) being the most abundant in the sludge, but few are completely exposed to the mud surface. In a fish pond, only resting eggs that are completely exposed to the surface of the mud or float in the water layer can germinate. Therefore, in the clear pond after the need to stir the surface silt with mud, the dormant eggs turned to the mud surface or water layer to promote its germination. In a certain temperature range, the germination time of rotifer dormant eggs shortens with increasing temperature. When the water temperature is 25°C, the number of rotifers can reach the peak after about 5 days after pond clearing. In the middle of May in the region, the water temperature is about 20.3°C. The rotifer peak takes about 8 days. Sometimes lime-cleared ponds may partially cover the mud surface with lime, affecting the overall germination of dormant eggs, thus delaying the emergence of rotifer peaks. Therefore, stirring the silt with a shovel after clear ponds can, on the one hand, allow the lime slurry to be fully mixed with the silt, so as to increase the effect of the lime clear pond. At the same time, the dormant eggs can be turned to the surface to increase the number of rotifers germination and reach a peak in advance. period.
The peak period of rotifer breeding usually lasts 3 to 5 days, after which the rotifer biomass is reduced by the invasion of enemy organisms or the lack of food. When the rotifers have not yet reached the peak, small clumps (such as abdomen puffer) will appear sporadically, and then gradually increase in quantity, ingesting large amounts of phytoplankton and organic debris in the water, inhibiting the growth and development of rotifers. In the case of sporadic emergence of small branchlets, the application of 0.03 to 0.05 ppm of crystal trichlorfon to kill it can appropriately extend the peak period of rotifers. Therefore, due to the problem of fry production can not be used when the pond is scheduled to extend the peak period of rotifers, if the rotifer peak period of the fish pond was delayed, large branches and copepods have been multiplying, only to change Water starts from fertilization. Therefore, it is necessary to properly arrange clear ponds, water injection and fertilization.
The rotifer biomass of the fish seedlings should reach 5,000 to 10,000 per liter of water and the biomass should be more than 20 milligrams. In the production, the number of rotifers can be observed visually, that is, using a glass beaker to calculate the number of small white spots (ie, rotifers) per milliliter of water against the sunlight, if there are 10 small white spots per ml of water, it is Every liter of water contains 10,000 rotifers. Therefore, if there are more than 5 small white spots per milliliter of water during observation, fish can be released.
In order to increase fertilizer efficiency, it is best to use the Quanchiposa method for fertilization. Spray it once a day or every other day, and use 10-20 kg per mu. This will ensure that the rotifers will receive sufficient food-organic crumbs to promote the growth and reproduction of rotifers, as well as save fertilizer. After many years of test results are obvious.
Fry ponds 15 days before the lower pond clear pond, after the disappearance of medicinal properties 50 to 60 cm. Immediately apply organic fertilizer to the pond to cultivate plankton. This method of breeding fry is called "fat pool." The fertilizer applied before the fry in the pond can be adapted to the local conditions. Generally, human excrement, chicken excrement, pig excrement, and cattle and horse excrement can also be used as fresh and perishable grasses. Fertilization methods used compost in the past. The amount of fertilizer used per mu was larger. Generally, the amount of manure was 200-250 kg per mu, and green manure was 300-400 kg. If the quality of grass was poor or the dosage was increased. In order to speed up fertilizer and water application of inorganic fertilizers, generally 4 kg of nitrogen fertilizer (ammonium sulfate, urea, etc.) and 4 kg of phosphate fertilizer (superphosphate) are applied per acre. The application of inorganic fertilizer needs Quanchiposa. Composting is to put the fertilizer in a shallow area of ​​sunny water, close to the water injection port, but away from the net position where it will go out of the pool. Fertilizers should be completely submerged in water to speed up decomposition of fertilizers. And it should be turned once every two days and three days in order to facilitate the diffusion of fertilizers into the water to improve fertilizer efficiency.
It is very important to cultivate the suitable feed for the fish pond Xiatang to master the fertilization time. After the fertilization, the plankton--the rotifers form the peak when the pond can ensure that there are enough food organisms in the fry. If the fry pond is too early or too late, the rotifer biomass does not reach the peak or the peak has passed. Fry biological shortage of fry will directly affect the survival rate and growth rate of fry. After fertilization in ponds, the peak of all kinds of zooplankton formation is: protozoa, rotifers, clafts, and copepods are the first to form peaks. In this process, the requirements for changes in the size of the fish from the pond to the summer flower pond are: rotifers and protozoa → small horns → large cladocera → copepods, which form a peak with the pond zooplankton The order is the same. The timely application of fertilizer in the pond can make good use of the consistency of the two, so that the rotifer peak appears well under the fish pond. Not only does the fish in the pond have enough palatability food, but it can also be developed in various development stages. Rich palatability feed. Therefore, the timely application of base fertilizer and fish seedlings is the key to raising fish fry.
The number of rotifers and their peak time are closely related to the number of resting eggs and the water temperature of rotifers. For example, if there is thick silt and strong water retention at the end of the pond, and a lot of organic fertilizer is applied to the pond, then there will be more dormant eggs in the silt, while in the newly opened pond or sandy bottom, the leakage is serious or the silt is thick but salt In higher ponds, rotifers have few resting eggs. The rotifer dormancy eggs are widely distributed in silt layers of different depths, gradually decreasing from the surface to the bottom and presenting a “Vâ€-shaped distribution, with the surface layer (0 to 5 cm) being the most abundant in the sludge, but few are completely exposed to the mud surface. In a fish pond, only resting eggs that are completely exposed to the surface of the mud or float in the water layer can germinate. Therefore, in the clear pond after the need to stir the surface silt with mud, the dormant eggs turned to the mud surface or water layer to promote its germination. In a certain temperature range, the germination time of rotifer dormant eggs shortens with increasing temperature. When the water temperature is 25°C, the number of rotifers can reach the peak after about 5 days after pond clearing. In the middle of May in the region, the water temperature is about 20.3°C. The rotifer peak takes about 8 days. Sometimes lime-cleared ponds may partially cover the mud surface with lime, affecting the overall germination of dormant eggs, thus delaying the emergence of rotifer peaks. Therefore, stirring the silt with a shovel after clear ponds can, on the one hand, allow the lime slurry to be fully mixed with the silt, so as to increase the effect of the lime clear pond. At the same time, the dormant eggs can be turned to the surface to increase the number of rotifers germination and reach a peak in advance. period.
The peak period of rotifer breeding usually lasts 3 to 5 days, after which the rotifer biomass is reduced by the invasion of enemy organisms or the lack of food. When the rotifers have not yet reached the peak, small clumps (such as abdomen puffer) will appear sporadically, and then gradually increase in quantity, ingesting large amounts of phytoplankton and organic debris in the water, inhibiting the growth and development of rotifers. In the case of sporadic emergence of small branchlets, the application of 0.03 to 0.05 ppm of crystal trichlorfon to kill it can appropriately extend the peak period of rotifers. Therefore, due to the problem of fry production can not be used when the pond is scheduled to extend the peak period of rotifers, if the rotifer peak period of the fish pond was delayed, large branches and copepods have been multiplying, only to change Water starts from fertilization. Therefore, it is necessary to properly arrange clear ponds, water injection and fertilization.
The rotifer biomass of the fish seedlings should reach 5,000 to 10,000 per liter of water and the biomass should be more than 20 milligrams. In the production, the number of rotifers can be observed visually, that is, using a glass beaker to calculate the number of small white spots (ie, rotifers) per milliliter of water against the sunlight, if there are 10 small white spots per ml of water, it is Every liter of water contains 10,000 rotifers. Therefore, if there are more than 5 small white spots per milliliter of water during observation, fish can be released.
In order to increase fertilizer efficiency, it is best to use the Quanchiposa method for fertilization. Spray it once a day or every other day, and use 10-20 kg per mu. This will ensure that the rotifers will receive sufficient food-organic crumbs to promote the growth and reproduction of rotifers, as well as save fertilizer. After many years of test results are obvious.