Su Xiangjin: my opinion on the Culture of Penaeus vannamei in soil Pond

Shrimp culture in soil ponds is generally semi-intensive culture mode. Taking Fangcheng Port in Guangxi as an example, the stocking density of shrimp culture is between 35 and 50 thousand per mu, which is a common stocking density. The seedling density in soil ponds with an area of less than 7 mu is mostly 50, 000 per mu, while in soil ponds with an area of 8 mu, the seedling density is generally about 4 ~ 45000 per mu, and about 35000 seedlings per mu above 15 mu, all of which are raised at the standard of 20 to 25 heads per jin. Compared with other areas, the planting density is a little lower, but the success rate is high, the water quality is easy to manage, the risk is low and the profit is high.

1 Water quality management of shrimp culture in soil ponds

The water quality management of shrimp culture in soil ponds is divided into early stage, middle stage and late stage. When we help farmers to deal with problems, we mainly judge and deal with them according to the number of days of shrimp culture.

1.1 Prophase of seedling release (20 days before seedling release):

Early planting, farmers are concentrated in the period from April 15 to May 1. This time belongs to the transition season of spring and summer, the climate is very unstable, the temperature difference between day and night is large, the light is weak, the water temperature is low, the shrimp fry is in the most sensitive stage, and it is also the peak period of shrimp disease. The characteristics of shrimp disease at this stage are: wide range of disease, high morbidity, high mortality and high pond drainage rate. Once the disease of shrimp is very difficult to treat, so we must "give priority to prevention", we must not wait until the disease of shrimp to take remedial measures. In my opinion, prawns in this period of time must grasp three key points of disease prevention.

1.1.1 low water temperature makes it difficult to fertilize water:

At this stage, the water temperature of the pond is generally between 20 and 25 ℃, and the growth and reproduction of algae and microorganisms are slow, so it is difficult to cultivate algae with fertilizer and water. At this time, it is best not to use bacteria, usually based on fertilizer. My practice is to put heavy fertilizer, with 10 mu 1 m water depth as the standard, using 4 packets of enzyme calcium fertilizer, 3 buckets of six anti-culture algae ointment, 8 packets of amino acid essence mixed sprinkling. After getting up with water and fertilizer, he immediately halved his manure the next day. If the fertilizer is not applied in time, the water will become clear on the third day. If you wait for the water to clear before topdressing, it will be very difficult to get fat again.

1.1.2 low water temperature, abnormal weather, difficult shelling and slow growth of prawns

Low water temperature, abnormal weather, shrimp not only poor appetite, weak physique, slow metabolism, but also many diseases, resulting in slow growth. My practice is to use degradable Lingjia ion to pour water on calcium (or nano-oxygen plus calcium) once a week to promote the shelling and hard shell of shrimp.

1.1.3 the climate is unstable and the temperature difference between day and night is large, so preventing stress is the key.

Prawns have a wide range of adaptability to temperature, but their adaptability to temperature difference is very poor. In order to resist the large temperature difference between day and night, shrimp consumes a lot of energy, causing strong stress, physiological disorder and decreased disease resistance. This is why the incidence of shrimp is high during this period. My practice is to use Jingning plus Jiejieling every 3 to 5 days.

At this stage, the common problem in the breeding process of the first shrimp and the second shrimp is that the water quality, such as mineral water, cannot be fattened many times. If you gain weight and can't get fat three times, don't get fat again. If it is sunny on the second day, change the overlord Satang with a package of 2 mu. Some farmers drag the bottom of the pond with branches or chains, and the water gets fat in the afternoon. In fact, the principle of dragging the bottom of the pond is the same as using the overlord of Daigai, both because the fat sinks to the bottom, activate it and allow the algae to absorb. However, in some cases, neither of these two methods works. I think: the fat must be enough, and definitely activate it. The reason why they can't get fat is that there are no algae in the water, and the algae can't reproduce. Be sure to wait 5-8 days, let the water form algae, slowly the water will become fat. At this time can not be topdressing, if then topdressing, when the water becomes fat, then the water will be too thick to see, once this batch of algae die, it will form a lot of mud crust. This kind of mineral water can easily cause the shrimp seedlings to die of hypoxia. Within 20 days after the release of the seedlings, the shrimp ponds are not equipped with aerators, and many farmers do not believe that the shrimp seedlings will be deprived of oxygen. Before 2010, I did not believe that shrimp seedlings would be deprived of oxygen, but that year in Guangpo, there were two cases in which shrimp seedlings died from lack of oxygen after seven days of release of mineral water.

A customer surnamed Qi reported to us that his shrimp fry had only been released for 7 days and all of them had floated due to lack of oxygen. Because the body of anoxic prawns, whether young or large, floating on the water is curved, while the body of diseased shrimps floating on the water is straight. If you look at it in this way, you can see that it is hypoxia or disease.

After we went to the scene to learn about the situation, we analyzed the reason with him: because the mineral water is free of algae, it is equivalent to a lack of oxygen source, and there is no dissolved oxygen in the water. If you do not turn on the aerator, there is no wind, the weather is stuffy, and the oxygen in the air does not dissolve into the water, so the shrimp seedlings are deprived of oxygen. He also agrees with our analysis. Later, he called the owner of the shrimp farm and said that his shrimp seedlings were not good, but now they all floated up, and a lot of them died. When the owner of the nursery farm came to have a look, he could not see that it was lack of oxygen, and later lost 420000 shrimp fry to the farmer. In the future, whenever we encounter mineral water and can't get fat, we let farmers sprinkle grains every night, using a pack of 3 mu of ponds.

In another case, topdressing in the morning, getting some water color in the afternoon, and turning into mineral water the next morning. In this case, there should be too many rotifers. If you pour a glass of water with a transparent glass, you will know whether it is rotifer or not. If there are too many rotifers, don't apply fertilizer any more, it will be a waste of money. Because the cultured algae are not fast enough for rotifers to eat, they can only stop feeding and let prawns fertilize after eating rotifers. It usually takes 3 to 5 days to stop the material.

1.2 in the middle of culture (20-50 days after stocking)

This period is already summer, with the continuous rise of air temperature and water temperature, feeding continues to increase, high excretion and high residual bait in shrimp ponds, corpses of various microorganisms, metabolism of algae, resulting in increased oxygen consumption. The increase of organic matter at the bottom of the pond and the further deterioration of the pond water created favorable conditions for the reproduction and development of various viruses, resulting in the occurrence of shrimp diseases. During this period, the water quality is the most unstable, the most easy to change, and the shrimp is the most prone to problems. So what farmers fear most is this period of time. In view of the climatic characteristics of this stage, how to improve water quality, we summarize the common situation as follows:

1.2.1 inverted algae

Reason: generally, the weather is changeable, sudden rain, or cloudy and rainy weather is more, the algae phase in the water is too single (we often say that the water quality is unstable, that's what it means), and a large number of algae die under stress. Another reason for inverted algae is that it is easy to produce inverted algae when the dissolved oxygen in the water is low, especially when it is cultured for about 40 days, the transparency of the water is low, the photosynthesis of the bottom algae is weak, the oxygen production capacity is low, and the residual bait increases the oxygen consumption factor in the water. make the whole water in a state of sub-anoxia, causing a large number of algae to die under hypoxia at night.

Countermeasures: the color of anti-algae water is muddy yellow, the pH value is very low, generally between 6.8 and 7.2, when algae is found, these two meals are cut off in the morning and noon, immediately throw lime, 10 mu / m water depth spill 100 kg of water for 2 hours, detoxify immediately, use 3 bottles of water purification king for every 10 mu pond; after 2 hours of detoxification, use 3 buckets of six anti-algal cream, 3 packets of enzyme calcium fertilizer, 5 packets of amino acid essence, 10kg urea mixed sprinkle, the role of urea is to fertilize quickly. Anti-stress and fat spill together, so add 6 packets of Jiangjieling and 6 packets of Yingzhining. In the afternoon, the water body basically improved. In the evening, sprinkle a circle with 6 packets of granule god and 6 packets of six-control bottom health ring pool.

1.2.2 concentrated yellow and green water

The most common and dangerous water color during this period is thick yellowish green. The surface of the water is not glossy and the water quality is sticky. When the aerator is turned on, there are a lot of suspended particles in the whole pond, which makes people feel very uncomfortable. This kind of water usually appears in sunny and hot weather, and it is still green in the morning. After a whole day of hot sun exposure, after 16:00 in the afternoon, the whole pond water becomes yellow, just like the color of beer. Turn on the aerator and stir it for 0.5 h. I feel like the water is a little greener back. It is found that if this situation is not dealt with in time, the water body will certainly become thick yellow and green water on the 3rd day. Once it turned into thick yellow and green water, it could not be treated within 7 days, and on the 7th day, the prawns floated in most cases.

We believe that the reason for the formation of thick yellow and green water is high temperature, hot sun exposure, the death of algae on the surface of the water body, and farmers do not fertilize in time to cultivate new algae. After playing the aerator all night, the algae in the bottom layer were stirred to the surface of the water body, and the next day they were sunburned to death. Over and over again, the algae in the whole pond were sunburned, turning the whole pond into stagnant water.

Once it is found that the water body turns yellow, 2 barrels of six anti-culture algae ointment, 2 barrels of algal happiness, 3 packets of Tricalcium and 5 packets of degradable Ling should be sprinkled in the whole pond on the second day (calculated at a water depth of 10 mu and 1 meter). And in the next three nights are sprinkled grain god, six control bottom health. If on the third day, the whole pond water has turned into thick yellow and green water, it should be detoxified with 3 bottles of water purification king first, and then sprinkled with 2 barrels of six anti-culture algae ointment, 3 barrels of algae happiness, 5 packets of green algae sources and 6 packets of biodegradable Ling 6 after two hours. At night, use Jiaoling 6 bag and ion pair calcium 6 bottles for 3 consecutive nights. In this way, the effect is very good. At this time, it is best not to use granule God and six control bottom health, because these two products release oxygen slowly.

1.2.3 thick green water

The color of thick green water is like that of urea alone. The pH changes little in the morning and evening, usually pH9.0 in the morning and pH9.2 in the afternoon. This kind of water color usually appears between 20 and 30 days after the release of prawns. There is something wrong with 3~125px shrimp, which is basically caused by this water color.

The surface of the thick green water is very clean, the aerator plays, there is no foam at all, from a distance, the whole pond is green, which makes people feel very comfortable. If you are inexperienced, you are likely to be misled by it and misjudged as good water. In fact, this kind of water color is also the most dangerous. If you squat down and look at it slowly, you will find that there are a lot of dead algae, suspended in the middle and upper layers of the water, with no glossiness at all, and the water body is very thin, but the aerator does not mix all night. At the end of the whole day, the color of the water body does not change much and the pH value does not change much. Generally speaking, this kind of water is most likely to be caused after a continuous week of overcast and rainy weather. We believe that the reason for the formation of thick green water is: when topdressing and cultivating green algae, shrimp does not like to eat this kind of green algae, the green algae grow more and more, the water color becomes thicker and thicker, and finally becomes thick green water. Once this green algae exceeds its growth cycle, it not only does not produce oxygen, but consumes oxygen. Shrimp to oxygen consumption, algae also need oxygen consumption, resulting in insufficient oxygen supply, shrimp long-term hypoxia, the liver can not bear, began to shrink, not treated for a long time, shrimp will float on the surface of the water. We believe that this kind of green algae is just like our usual green vegetables, which have been grown, but if we don't pick it back and eat it, after the peak growth period, it will slowly grow old and turn yellow. To treat this kind of water, take the water depth of 10 mu and 1m as the standard, detoxify it with 3 bottles of purified water king first, and then use 2 bottles of new live bacteria king and 5 packets of healthy algae twice in 3 days after two hours. Sprinkle the bottom of the pond healthily with granule god and six control bottom for three consecutive nights. On the fifth day, the water naturally turned dark green and had a good gloss. For this kind of water, this treatment effect is the best.

80% of the drainage ponds or the jejunal stomach of prawns in the region are caused by this thick yellow-green water and thick green water.

1.2.4 muddy water, turbid water

Because of these two kinds of water colors, there are many drainage ponds, but there are also many people who raise them successfully. Success depends on how you deal with it in the early stage.

I suggest chasing heavy fat. According to the standard calculation of 10 mu 1 m water depth, 3 bottles of purified water king were used for detoxification, and then 3 buckets of six anti-algal ointment, 3 packets of enzyme calcium fertilizer, 5 packets of amino acid essence and 5 packets of Jiangjieling were mixed and sprinkled 3 times in 6 days. Use 3 packets of Tricalcium and 3 bottles of nano-oxygen in the evening, every other night. Treated in this way, sometimes the water body may not get fat, but there is no problem with prawns. After 7 days, the shrimp did not surface, which proved that the shrimp had adapted to this environment. After that, the shrimp will be raised well by strengthening the dissolved oxygen at the bottom of the water body.

The oxygenation must be turned off before this kind of water is fertilized. After topdressing, you can't turn on the aerator on the same day. There is too much floating mud and the water cannot be fertilized. Many farmers gain weight, but they can't get fat, which is often the reason why they don't turn off the aerator.

There is another method that is more effective. We used it frequently in the first two years, but we seldom used it in the past two years, unless specifically requested by farmers. Because when individual farmers use it on their own, the water bounces back two or three days later. I deal with it like this: first treat the floating mud, then treat the water. When the aerator was stirred all night, the water was basically muddy. Sprinkle the granules first, turn off the oxygenation, and then sprinkle aluminum chloride. After this treatment, the water body is very fresh, and all the floating dust is adsorbed to the bottom of the pond. Topdressing for 2 hours, with 10 mu 1 m water depth as the standard, 3 buckets of six anti-culture algae ointment, 3 packages of enzyme calcium fertilizer, 5 packets of essence and 10kg urea were mixed and sprinkled. The water body can basically come back green in the afternoon, but only if it is sunny.

1.2.5 treatment of foam

Bubbles are also a common problem at this stage. The cause of foam is the aging of algae, the death of a large number of beneficial algae, algae lost the function of decomposition and self-purification, so there are a lot of foam. If we want to solve this problem, we must cultivate new algae to replace aging algae. In this way, the problem is solved. Many farmers are sprinkling ions on calcium or raw oil, this is just a temporary cure, as soon as the aerator foam comes again.

1.2.6 the bottom of the pond stinks

Reason: perennial deposition of bottom mud and a variety of zooplankton humus, dead algae rot, causing the bottom of the pond to stink. You can first detoxify the water purification king, and then sprinkle the black gold god and the powder live bacteria king in the whole pool.

1.3 later stage of culture (stocking for more than 50 days)

In the later stage of shrimp culture, the water quality gradually tended to be stable, and there was no great change. With the continuous topdressing and replenishment of bacteria, the water body will generally turn into red water, soy sauce water or dark green water.

We all think that red and soy sauce are dangerous colors and can't raise shrimp. But after observation and tracking, I found that as long as the maintenance is proper, these two kinds of water color can also cultivate shrimp. The advantage of these two water colors is that they are stable no matter how the weather changes. After the heavy rain, if you catch up with some fertilizer and bacteria, its gloss and fertility will be very good. But many farmers do not like these two kinds of water color, must adjust it to dark green. Dark green is an ideal water color recognized by farmers.

To turn red water or soy sauce water into dark green, my practice is to detoxify the pond with 3 bottles of water purification king for every 10 mu of 1m deep pond, and then sprinkle it with 7 packets of nitrosoxide, 7 packets of amino acid essence and 7 packets of flexible 100 after two hours. After this treatment, it can basically achieve the effect of dark green. However, the premise is that prawns must be more than 60 days old.

In the course of our work, we often hear farmers say that the pH value of the pond is very low and a lot of lime has been spilled, but it is always not high and the splashing is getting lower and lower. After spilling for a few days, the whole pond water has been splashed out. This is because lime kills algae, so the spill is getting lower and lower. If lime is thrown in the morning for two consecutive days, but the pH value in the afternoon is lower than the day before. You should stop throwing lime blindly. What I do is to pound the lime into lime particles, mix calcium magnesium phosphate fertilizer to dry sprinkle on the bottom of the pond, and then fertilize the pond, we can solve this problem.

We often receive phone calls from farmers saying that his pond water is very thick, the transparency is too small, and he has used live bacteria many times, but it has no effect at all. If you encounter this kind of situation, you must ask whether it is thick or muddy, and some farmers are often thick and muddy. Thick is due to the vigorous growth of algae, too much, and muddy is too much floating mud, there is no algal phase, in fact, it is lack of fertilizer. If you release bacteria, it is tantamount to making things worse, more and more muddy, and finally become muddy water. Therefore, when the water is thick, we use bacteria, and when the water is muddy, we use fertilizer.

2 common problems in shrimp culture in soil ponds

2.1 on the deep-water feed platform and the shallow-water feed platform, the eating speed of shrimp is different, which is caused by, on the one hand, in the early stage of culture, the deep-water food is eaten quickly, while the shallow-water material is eaten slowly, this is because the water body is transparent and prawns are afraid of light. Concentrated in the deep water area, the material naturally eats fast. On the other hand, in the later stage of culture, the food in shallow water eats quickly, while that in deep water eats slowly. this is because the bottom dirty in the deep water area, the bottom dissolved oxygen is insufficient, and the prawns all go to the shallow water area. Therefore, in the later stage of culture, the water depth should be controlled between 1.3m and 1.5m.

2.2 the reason why prawns suddenly eat slowly, on the one hand, it is necessary to consider whether they are stressed by sudden changes in the environment. Second, whether the shrimp is shelled or not.

2.3 when prawns eat a lot of food and grow fast, it is easy to get sick, what is the cause?

When the prawns were raised to 5~200px, for a few days, the prawns were fed very quickly, with a range of 5-7.5kg per meal. On the 3rd day, the prawns floated. The reason is that shrimp eat too much, liver, gastrointestinal burden is too heavy, excessive accumulation of toxins in the body, causing metabolic disorders, coupled with dissolved oxygen can not keep up, so the disease. Once you encounter prawns eating fast, much faster than the normal eating speed, one-time can not add too many ingredients, lunch this meal had better cut by half.

2.4 causes of liver yellowing of Penaeus chinensis

In the early stage of culture, that is, the shrimp below 100px, its liver is much more yellow, this is because it has not been transferred to the liver. Just pipe the water well and increase the dissolved oxygen.

In the middle and later stage of culture, the dissolved oxygen at the bottom is insufficient, and the shrimp liver turns yellow and gradually shrinks when it is in the state of hypoxia for a long time. If it is not dealt with in time, it will float on the surface. Treatment: in addition to nourishing the water and replenishing exogenous oxygen in the evening, we should also assist in the use of liver protection products. Many farmers say that his aerator is on for 24 hours and there should be no problem of insufficient bottom oxygen. The aerator cannot produce oxygen, it uses the convection of water to dissolve a small amount of oxygen in the air into the water, and there are many dead corners of dissolved oxygen in the pond, which can not be solved by the aerator.

2.5 Shrimp steals to death

If the shrimp is made early and killed within 20 days of releasing the seedlings, the farmers will generally discharge the ponds directly and release the seedlings again. If the shrimp is made late and the shrimp is stolen to death within 20 days, the farmers generally do not deal with it, do not drain the pond, leave it there and leave it to fend for itself. If the prawns die in the middle and later stages, the liver is basically atrophied. Whether it is live shrimp or dead shrimp, after opening the head and chest armour, take out the liver and feel it with your hands, there is no resilience at all, which proves that the liver has shrunk seriously. Some individual farmers believe that sulfite is too high poisoning, resulting in stealing to death. In my opinion, for all prawns that are more than 60 days old, more than 90% of the pond nitrite is on the high side. Although the nitrite in many ponds is on the high side, there is no shrimp stolen to death. So stealing death is due to shrimp living in hypoxia for a long time, not treated for a long time, or the treatment effect is not ideal, resulting in liver atrophy slowly. Once the weather changes, such as high temperature and low pressure, prawns begin to steal to death. All the prawns stolen to death are at the bottom of the impeller aerator in the middle, because the dissolved oxygen in this place is relatively high, and these weak and sickly shrimps all run in this direction, so they all die here. Suggestion: adjust the water to an ideal state and replenish exogenous oxygen at night. When dealing with the stolen prawns, ask the farmers to put a net under the impeller aerator in the middle of the pond. Watch it twice a day, if more and more every day, difficult to control, then have no choice but to drain the pond.

2.6 hypoxia

General hypoxia can be basically solved with Jianjianling and ion-pair calcium. If it is the hypoxia caused by the fever at the bottom of the pond, glucose must be added, 2.5kg per mu. Otherwise, the prawns will not sink. Another kind of hypoxia is that you use a variety of oxygenating products, including degradative and ion-pair calcium, and you can't do it no matter how many aerators you add. In such a situation, water should be brought in quickly. If the tide level is not suitable, pump it with a pump, preferably adding water 1250px within 1 hour. Adding water is also a way to quickly increase dissolved oxygen.

In Guangpo, every year, individual farmers ask me what to use to replace degradable spirit, and I say it can't be replaced. The function of Jiangjieling is to improve the permeability of water, eliminate the surface tension of water, form convection between oxygen in water and oxygen in air, and solve the problem of hypoxia, but it is not like grain oxygen to produce oxygen directly, too much grain oxygen will hurt water.

2.7 under what circumstances can shrimp be saved and under what circumstances can't be saved

The shrimp floating on the water is the smallest kind of shrimp in the whole pond. This kind of shrimp is lucky and less evil, and can be saved. The prawns floating on the water are full and full, and this kind of shrimp can also be saved. If it is the largest shrimp in the whole pond, that kind of shrimp is unlucky and had better not be saved. Before taking medicine, be sure to throw the net and observe the liver, vitality and body color of prawns before you can decide whether to save or not.

When observing the shrimp liver, remove the capsule of the liver. The color of the normal liver is pig liver. If the liver is found to be red, indicating that the liver has shrunk seriously, this kind of shrimp had better not be saved. If it is red with a little green inside, the liver indicates that it is just beginning to atrophy, and this situation can be saved.

Author: Su Xiangjin, Hainan excellent Biology Co., Ltd.