The whitebait is one of the most valuable aquatic products in China. It has long been known as a treasure on the table and has long enjoyed a good reputation both at home and abroad. In order to develop this precious fish species, China’s aquatic research institutes have explored the success of large-scale water migration of whitebait and explored the pond culture technology of large whitebait, opening up new avenues for the development of silverfish production.
First, the habit of big silver fish in the pond
1. Inhabiting habits The whitebait lived in the middle and lower layers of the pond. Except for oxygen deficiency, it was rarely found in the upper layer. For example, the pool week and the bottom of the pond had water weeds, and often drilled into it. Even when they were disturbed, they even bored into the bottom mud. in. Juveniles have strong phototaxis and can be induced into groups using light at night. They can be used to examine their growth and feeding conditions, and adults do not have phototaxis.
2. Feeding habits Juveniles start to eat on the 10th day after they are released from the film. The open bait is a rotifer. Afterwards, the larger and more readily available zooplankton is gradually used as food. The order is nauplii, copepod larvae, cladocera and cockroach. Adults. The whitebait is a meat-eating animal and it is based on small fish and shrimp.
3. Breeding habits In the pond, large silverfish can normally grow and develop until the gonads mature and spawn themselves. The gonadal development and spawning characteristics are basically the same as natural waters. In the middle and lower reaches of the Yangtze River, the peak of the spawning season is from late December to early January. Generally in hard-bottom ponds with aquatic plants spawning more concentrated, fertility rate of up to 80% to 90%.
Second, the pond conditions generally choose the old pond, requiring fresh water, no pollution, sheltered from the sun, easy drainage. A single pool of 3 acres to 5 acres, sets of 5 acres to 10 acres of pool, the pool depth of 2 meters, sediment 0.2 meters, the amount of water around the pool weeks. Generally not mixed with animal feeding and omnivorous fish.
1. Prepare the seedling stocking pool to pull the net of the breeding fish's fertilizer ponds, turn the surface mud properly, and pour the pool water into the stocking pond after the desilting. Because the temperature is low when the big whitebait is eating, the pond water quality is difficult to cultivate, especially the density of rotifers is low. Use the home fish pond water and input the rotifer dormant eggs to quickly increase the bait density in the stocking pond. This work should be completed two weeks before stocking, and the water depth should be 0.6 meters before stocking.
2. Seedlings from the seedling source for the first time. Mature broodstock can be collected in natural waters and artificial insemination can be performed on site to obtain fertilized eggs (fertilized eggs are sold in Taihu Lake and Dianchi Lake). Fertilized eggs can be hatched in the indoor water, when the water temperature is maintained at 4 °C ~ 6 °C, 30 days to 40 days film, the hatching rate is higher, better stocking effect. After testing, fertilized eggs hatched after the end of February, easier to obtain food to eat, which will help improve the survival rate of seedlings.
3. Restocking methods Production practices have shown that large silverfish have a better stocking effect than embryos in the embryonic period. Normally, eggs are hatched into the pool one week before the film is laid out. Under normal conditions, 20,000 fertilized eggs are laid in the mu, and about 30 kilograms of big whitebait can be caught from September to October. The stocking rate is too large, the food is insufficient, and the survival rate is low. The depth of the pool is about 1 meter to 1.5 meters.
4. Cultivation techniques The larvae mainly feed on rotifers and nauplii. Generally 10 days after hatching, food is eaten and 3 days after food is eaten, it will gradually die if there is no palatability feed. Therefore, the stocking pond should be fertilized in advance to ensure that there is enough food when it is eaten. The fully fermented manure is applied, and lime water is suitably used. After 10 days to 15 days, the color of the water turns thick and the rotifers can reach a considerable density.
Juveniles mainly eat unbranched, horned, copepods, and chironomid larvae. At this time, it can be used for fertilization. The amount of fertilizer applied is controlled according to the color of the water and the temperature of the water. The transparency of the pool water should be as large as 40 cm or more and the water depth should be maintained at about 2 meters.
Third, adult fish breeding
1. Feeding sufficient fish into the fish stage (above 40 mm in length) The food intake is large, the growth rate is significantly accelerated, and fertilization must be performed to maintain the density of plankton. Generally, the fermented fertilizer is applied and a small amount of soymilk can be splashed, usually every day. With 250 grams to 500 grams of soybeans, according to the water quality conditions.
2. To prevent the floating head of large whitebait to have higher oxygen demand than ordinary fish, and floating heads always occur first in polyculture. When the water temperature is 20°C, there is a floating head phenomenon. If the floating head phenomenon is found not to take emergency measures immediately, a large number of deaths will occur. The method of preventing floating heads is to reduce the amount of fertilizers and not to overfeed the food organisms. If the pool water is too fat, the pool water should be renewed as soon as possible. If necessary, aerators can be used to increase oxygen or aerators to increase oxygen.
3. Pay attention to the conversion of the diet of the big whitebait. There is a conversion period, from the feeding of cladocera and copepods to the gradual conversion of meat. If fish and shrimp are found in the intestines of silver fish whose body length is close to 80 mm, it indicates that food habits are In the process of transformation, small fish and shrimp should be introduced in time and maintain a certain density, which can greatly promote the growth rate of large whitebait. It was found in the experiment that the amount of green shrimp eggs was introduced in the Yangtze River Valley in May, and hatched shrimp just caught up with the big silver. The fish changed its feeding period.
4. To prevent high temperature in summer and high temperature season, the water depth should be more than 2.5 meters, and it can not reach the water depth requirement. Shading measures can be taken to prevent high temperature.
First, the habit of big silver fish in the pond
1. Inhabiting habits The whitebait lived in the middle and lower layers of the pond. Except for oxygen deficiency, it was rarely found in the upper layer. For example, the pool week and the bottom of the pond had water weeds, and often drilled into it. Even when they were disturbed, they even bored into the bottom mud. in. Juveniles have strong phototaxis and can be induced into groups using light at night. They can be used to examine their growth and feeding conditions, and adults do not have phototaxis.
2. Feeding habits Juveniles start to eat on the 10th day after they are released from the film. The open bait is a rotifer. Afterwards, the larger and more readily available zooplankton is gradually used as food. The order is nauplii, copepod larvae, cladocera and cockroach. Adults. The whitebait is a meat-eating animal and it is based on small fish and shrimp.
3. Breeding habits In the pond, large silverfish can normally grow and develop until the gonads mature and spawn themselves. The gonadal development and spawning characteristics are basically the same as natural waters. In the middle and lower reaches of the Yangtze River, the peak of the spawning season is from late December to early January. Generally in hard-bottom ponds with aquatic plants spawning more concentrated, fertility rate of up to 80% to 90%.
Second, the pond conditions generally choose the old pond, requiring fresh water, no pollution, sheltered from the sun, easy drainage. A single pool of 3 acres to 5 acres, sets of 5 acres to 10 acres of pool, the pool depth of 2 meters, sediment 0.2 meters, the amount of water around the pool weeks. Generally not mixed with animal feeding and omnivorous fish.
1. Prepare the seedling stocking pool to pull the net of the breeding fish's fertilizer ponds, turn the surface mud properly, and pour the pool water into the stocking pond after the desilting. Because the temperature is low when the big whitebait is eating, the pond water quality is difficult to cultivate, especially the density of rotifers is low. Use the home fish pond water and input the rotifer dormant eggs to quickly increase the bait density in the stocking pond. This work should be completed two weeks before stocking, and the water depth should be 0.6 meters before stocking.
2. Seedlings from the seedling source for the first time. Mature broodstock can be collected in natural waters and artificial insemination can be performed on site to obtain fertilized eggs (fertilized eggs are sold in Taihu Lake and Dianchi Lake). Fertilized eggs can be hatched in the indoor water, when the water temperature is maintained at 4 °C ~ 6 °C, 30 days to 40 days film, the hatching rate is higher, better stocking effect. After testing, fertilized eggs hatched after the end of February, easier to obtain food to eat, which will help improve the survival rate of seedlings.
3. Restocking methods Production practices have shown that large silverfish have a better stocking effect than embryos in the embryonic period. Normally, eggs are hatched into the pool one week before the film is laid out. Under normal conditions, 20,000 fertilized eggs are laid in the mu, and about 30 kilograms of big whitebait can be caught from September to October. The stocking rate is too large, the food is insufficient, and the survival rate is low. The depth of the pool is about 1 meter to 1.5 meters.
4. Cultivation techniques The larvae mainly feed on rotifers and nauplii. Generally 10 days after hatching, food is eaten and 3 days after food is eaten, it will gradually die if there is no palatability feed. Therefore, the stocking pond should be fertilized in advance to ensure that there is enough food when it is eaten. The fully fermented manure is applied, and lime water is suitably used. After 10 days to 15 days, the color of the water turns thick and the rotifers can reach a considerable density.
Juveniles mainly eat unbranched, horned, copepods, and chironomid larvae. At this time, it can be used for fertilization. The amount of fertilizer applied is controlled according to the color of the water and the temperature of the water. The transparency of the pool water should be as large as 40 cm or more and the water depth should be maintained at about 2 meters.
Third, adult fish breeding
1. Feeding sufficient fish into the fish stage (above 40 mm in length) The food intake is large, the growth rate is significantly accelerated, and fertilization must be performed to maintain the density of plankton. Generally, the fermented fertilizer is applied and a small amount of soymilk can be splashed, usually every day. With 250 grams to 500 grams of soybeans, according to the water quality conditions.
2. To prevent the floating head of large whitebait to have higher oxygen demand than ordinary fish, and floating heads always occur first in polyculture. When the water temperature is 20°C, there is a floating head phenomenon. If the floating head phenomenon is found not to take emergency measures immediately, a large number of deaths will occur. The method of preventing floating heads is to reduce the amount of fertilizers and not to overfeed the food organisms. If the pool water is too fat, the pool water should be renewed as soon as possible. If necessary, aerators can be used to increase oxygen or aerators to increase oxygen.
3. Pay attention to the conversion of the diet of the big whitebait. There is a conversion period, from the feeding of cladocera and copepods to the gradual conversion of meat. If fish and shrimp are found in the intestines of silver fish whose body length is close to 80 mm, it indicates that food habits are In the process of transformation, small fish and shrimp should be introduced in time and maintain a certain density, which can greatly promote the growth rate of large whitebait. It was found in the experiment that the amount of green shrimp eggs was introduced in the Yangtze River Valley in May, and hatched shrimp just caught up with the big silver. The fish changed its feeding period.
4. To prevent high temperature in summer and high temperature season, the water depth should be more than 2.5 meters, and it can not reach the water depth requirement. Shading measures can be taken to prevent high temperature.
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