Su Xiangjin Shares His Experience and Insights on Farming Whiteleg Shrimp (Litopenaeus vannamei) in Earthen Ponds

Shrimp farming in earthen ponds is generally a semi-intensive model. Taking Fangchenggang, Guangxi as an example, the stocking density for shrimp farming is between 35,000 and 50,000 postlarvae per mu, which is a common stocking density. For earthen ponds under 7 mu, the stocking density is mostly 50,000 per mu, while for earthen ponds of 8-12 mu, the stocking density is generally around 40,000-45,000 per mu, and for ponds over 15 mu, the stocking density is around 35,000 per mu. In all cases, shrimp are stocked to be grown to a size of 20-25 shrimp per jin. Compared with other regions, this stocking density is a bit lower, but the success rate is high, water quality is easy to manage, risk is low, and profit is high.

1 Water Quality Management for Shrimp Farming in Earthen Ponds

Water quality management for shrimp farming in earthen ponds is divided into the early, middle, and late stages. When we help farmers deal with problems, we mainly judge and handle them based on the number of days the shrimp have been in the pond.

1.1 Early Stage Before Stocking (within 20 days before stocking):

For the early crop, farmers all concentrate their stocking between April 15 and May 1. This time falls at the turn of spring and summer, when the climate is very unstable, the temperature difference between day and night is large, light is weak, and water temperature is low. Shrimp postlarvae are at their most sensitive stage, and it is also the peak period for shrimp disease outbreaks. The characteristics of shrimp disease at this stage are: a wide range of outbreaks, a high incidence rate, a high mortality rate, and a very high pond-culling rate. Once shrimp get sick, they are very difficult to treat, so you must "focus on prevention," and absolutely must not wait until shrimp get sick before taking remedial measures. In my view, shrimp at this time must have 3 key disease-prevention points handled well.

1.1.1 Low water temperature makes it difficult to fertilize the water:
At this stage, pond water temperature is generally between 20-25°C, algae and microorganisms grow and reproduce slowly, and fertilizing the water to culture algae is difficult. At this time, it is best not to use bacteria, and generally to focus on fertilizer. My approach is to apply heavy fertilizer. Based on 10 mu at 1 m water depth as the standard, use 4 bags of enzyme calcium fertilizer, 3 buckets of Six-Resistance Algae-Culture Paste, and 8 bags of amino acid essence, mix and splash. After the water is fertilized, immediately halve the amount for follow-up fertilization the next day. If you do not fertilize in time, the water will become clear on the third day. If you wait until the water becomes clear before fertilizing again, it will be very difficult to fertilize it again.

1.1.2 Low water temperature and abnormal weather make it difficult for shrimp to molt, and growth is slow
When water temperature is low and weather is abnormal, shrimp not only have poor appetite, weak constitution, and slow metabolism, but also suffer from many diseases, resulting in slow growth. My approach is: use Degrading Spirit plus Ionic Calcium (or Nano Oxygen plus Teli Calcium) once a week, splashed in the water, to promote molting and shell hardening in shrimp.

1.1.3 Unstable climate and large day-night temperature differences make stress prevention key
Shrimp adapt to a wide range of temperatures, but their ability to adapt to temperature differences is very poor. To resist large day-night temperature differences, shrimp consume a great deal of energy, causing strong stress, physiological disorder, and reduced disease resistance. This is why the incidence of shrimp disease is high during this period. My approach is: every 3-5 days, use Stress Relief plus Degrading Spirit once.
At this stage, the common problem appearing in the farming process for both the first crop and the second crop of shrimp is that the water quality is like mineral water, and repeated fertilization fails to fertilize it. If you apply heavy fertilizer and still fail to fertilize it after three attempts, then do not fertilize again. If the next day is sunny, use 1 bag of Bottom Improvement Overlord per 2 mu and broadcast it over the pond. Some farmers drag branches or iron chains across the pond bottom, and by the afternoon the water has become fertilized. In fact, dragging the pond bottom and using Bottom Improvement Overlord work on the same principle: because the fertilizer has settled to the bottom, activating it so that algae seeds can absorb it. But occasionally, neither method works. In my view: the fertilizer applied is definitely sufficient, and it has absolutely been activated. The reason it cannot be fertilized is that the water body has no algae seeds, so algae cannot reproduce. You must wait 5-8 days, let algae seeds form in the water, and then the water will slowly become fertilized. At this time you must not fertilize again; if you do, once the water body becomes fertilized, the water will be so dense it is unbearable to look at, and once this batch of algae dies, it will form a large amount of mud skin. This kind of mineral water easily causes postlarvae to die from hypoxia. After farmers stock postlarvae, within 20 days there are no aerators installed in the shrimp pond, and many farmers also do not believe that postlarvae can suffer hypoxia. Before 2010, I also did not believe that postlarvae could suffer hypoxia, but that year in Guangpo there were two cases in which postlarvae were stocked in mineral water for 7 days and then died from hypoxia.
A customer surnamed Qi reported to us that his postlarvae had just been stocked for 7 days and all floated up due to hypoxia. This is because hypoxic shrimp, whether postlarvae or large shrimp, have curved bodies when floating on the water surface; whereas diseased shrimp floating on the water surface have straight bodies. With one look, you can tell whether it is hypoxia or disease.
After we went to the site to understand the situation, we analyzed the cause with him: because mineral water has no algae, it is equivalent to lacking an oxygen source, and there is not a bit of dissolved oxygen in the water. If you do not turn on the aerator, and there is no wind, and the weather is stuffy, oxygen in the air cannot dissolve into the water, so the postlarvae suffer hypoxia. He also agreed with our analysis. Later he called the boss of the postlarvae farm and said his postlarvae were no good, that they had all floated up now, and many had died. The boss of the hatchery came over to take a look, and he also could not tell it was hypoxia, and later compensated this farmer with 420,000 postlarvae. After that, whenever we encountered mineral water and the water could not be fertilized for those few days, we had farmers broadcast Granule Spirit every night, using 1 bag for a 3-mu pond.
There is another situation: in the morning fertilizer is applied, in the afternoon some water color develops, and the next morning it turns back into mineral water. This situation is probably due to too many rotifers. Take a transparent glass cup and scoop a cup of water, and you will know whether it is rotifers. If there are too many rotifers, do not fertilize again; fertilizing again just wastes money. This is because the algae cultured cannot be eaten by the rotifers fast enough, so you can only stop feeding, let the shrimp eat the rotifers, and then fertilize again. Generally, stopping feeding for 3-5 days is enough.

1.2 Middle Stage of Farming (20-50 days after stocking)

    This period is already summer. As air and water temperatures continue to rise and feed input continuously increases, the high excretion and high residual bait in shrimp ponds, the corpses of various microorganisms, and the metabolism of algae all lead to increased oxygen consumption. The increase of organic matter at the pond bottom further worsens the pond water, creating favorable conditions for the reproduction and development of various viruses, causing the occurrence of shrimp diseases. This period has the most unstable water quality, is the most prone to change, and is the period when shrimp are most likely to have problems. So what farmers fear most is this period. In response to the climate characteristics of this stage, regarding how to maintain good water quality, we summarize the common situations as follows:

1.2.1 Algae crash
Cause: generally due to capricious weather, sudden rainfall, or more rainy weather, the algae phase in the water body is too single (what we often call unstable water quality means this), and large numbers of algae die from stress. Another cause of algae crash is: when dissolved oxygen in the water is low, algae crash is also likely to occur, especially when shrimp have been raised to around 40 days, water transparency is low, photosynthesis of bottom-layer algae is weak, oxygen production capacity is low, and residual bait increases oxygen-consuming factors in the water, making the entire water body sub-hypoxic and causing large numbers of algae to die from hypoxia at night.
Countermeasures: After an algae crash, the water color is muddy yellow, and pH is very low, generally between 6.8-7.2. When an algae crash is discovered, stop feeding for the morning and noon meals, immediately splash lime, using 100 kg per 10 mu/m water depth; after 2 h, immediately detoxify, using 3 bottles of Water Purification King per 10-mu pond; 2 h after detoxification, mix and splash 3 buckets of Six-Resistance Algae-Culture Paste, 3 bags of enzyme calcium fertilizer, 5 bags of amino acid essence, and 10 kg urea. The role of urea is to fertilize quickly. Anti-stress products are splashed together with the fertilizer, so add 6 bags of Degrading Spirit and 6 bags of Stress Relief. By the afternoon, the water body has basically improved somewhat. At night, use 6 bags of Granule Spirit and 6 bags of Six-Control Bottom Health and sprinkle them around the pond in a circle.

1.2.2 Dense yellow-green water
The most common and also most dangerous water color during this period is dense yellow-green. The water surface has no luster, and the water quality is viscous. When the aerator is turned on, there are many suspended particles in the whole pond, making people feel very uncomfortable. This kind of water generally appears in sunny high-temperature weather. In the morning the water is still green, and after a whole day of intense sun exposure, after 16:00 in the afternoon, the whole pond of water becomes yellow, like the color of beer. Turn on the aerator and stir it for 0.5 h, and you feel the water body has turned a bit green again. If this situation is discovered and not handled in time, on the 3rd day the water body will definitely become dense yellow-green water. Once it becomes dense yellow-green water, if it cannot be handled well within 7 days, then by the 7th day, in most cases the shrimp will float up.
We believe the cause of dense yellow-green water is high-temperature weather and intense sun exposure causing algae on the water surface to die from sunscald, while farmers do not fertilize in time to cultivate new algae. The aerator runs all night, stirring bottom-layer algae up to the water surface, and the next day they are again killed by sunscald. This repeats, and all the algae in the whole pond are killed by sunscald, turning the whole pond of water into dead water.
Once the water body is found to have turned yellow, the next day immediately mix and splash over the whole pond 2 buckets of Six-Resistance Algae-Culture Paste, 2 buckets of Algae Happiness, 3 bags of Teli Calcium, and 5 bags of Degrading Spirit (calculated for 10 mu at 1 m water depth). And on the following three nights, broadcast Granule Spirit and Six-Control Bottom Health. If by the 3rd day the whole pond of water has already become dense yellow-green water, first use 3 bottles of Water Purification King to detoxify, and 2 hours later mix and splash 2 buckets of Six-Resistance Algae-Culture Paste, 3 buckets of Algae Happiness, 5 bags of Green Algae Source, and 6 bags of Degrading Spirit. At night, use another 6 bags of Degrading Spirit and 6 bottles of Ionic Calcium, continuously for 3 nights. Handled this way, the effect is very good. At this time, it is best not to use Granule Spirit and Six-Control Bottom Health, because these two products release oxygen slowly.

1.2.3 Dense green water
The color of dense green water is like the color produced by using urea alone as fertilizer. The pH change in the morning and evening is not large, generally pH 9.0 in the morning and around pH 9.2 in the afternoon. This water color generally appears 20-30 days after shrimp stocking, and problems in 3-125 px shrimp are basically caused by this water color.
The surface of dense green water is very clean. When the aerator is turned on, there is not a bit of foam. Seen from a distance, the whole pond of water is green and makes people feel very comfortable. If you lack experience, you are very likely to be misled by it and mistakenly judge it as good water. In fact, this water color is also the most dangerous. If you squat down and look slowly, you will find many dead algae, suspended one grain at a time in the middle and upper layers of the water, with no luster at all. The water body is very lean, but the aerator can stir it all night without making it cloudy. Over a whole day, the water body color changes little, and the pH value also changes little. Generally, after a continuous week of rainy weather, this kind of water is most likely to result. We believe the cause of dense green water is: when fertilizing to culture green algae, the shrimp do not like to eat this green algae, so the green algae grow more and more, the water color becomes denser and denser, and finally it becomes dense green water. Once this green algae exceeds its growth cycle, it not only does not produce oxygen, but instead consumes oxygen. Shrimp consume oxygen, and algae also consume oxygen, leading to insufficient oxygen supply. Shrimp remain in a low-oxygen state for a long time, the liver cannot bear it, and begins to shrink. If not handled for a long time, the shrimp then float on the water surface. We believe this green algae is like the green vegetables we usually plant: once the vegetables have grown, if we do not pick them to eat, after the vigorous growth period they slowly become old and yellow. To handle this kind of water, based on 10 mu at 1 m water depth as the standard, first use 3 bottles of Water Purification King to detoxify, and 2 hours later use 2 bottles of New Live Bacteria King and 5 bags of Algae Health, twice in 3 days. For three consecutive nights, use Granule Spirit and Six-Control Bottom Health and sprinkle them on the pond bottom. On the 5th day the water naturally becomes dark green with very good luster. For this kind of water, this treatment has the best effect..                 
In this region, 80% of pond culling or empty intestines and empty stomachs in shrimp are caused by this dense yellow-green water and dense green water.

1.2.4 Muddy water and turbid water
Many ponds are culled because of these two water colors, but many people also succeed in farming with them. Whether you succeed or not depends on how you handle it in the early stage.

I suggest applying heavy fertilizer. Calculated for 10 mu at 1 m water depth as the standard, first use 3 bottles of Water Purification King to detoxify, and after 2 h mix and splash 3 buckets of Six-Resistance Algae-Culture Paste, 3 bags of enzyme calcium fertilizer, 5 bags of amino acid essence, and 5 bags of Degrading Spirit, using 3 times within 6 days. At night, use another 3 bags of Teli Calcium and 3 bottles of Nano Oxygen, once every other night. Handled this way, sometimes the water body may not become fertilized, but the shrimp will be fine. After 7 days, if the shrimp have not floated up, it proves the shrimp have already adapted to this environment. After that, strengthen dissolved oxygen at the bottom of the water body, and the shrimp will be raised very well.
Before fertilizing this kind of water, you must turn off the aerator. After fertilizing, the aerator must not be turned on that day. If there is too much floating mud, the water cannot be fertilized. Many farmers apply heavy fertilizer and still cannot fertilize the water, and in many cases this is because they did not turn off the aerator.
There is another method that is quite effective. We used it often in the past two years, but in the last two years we have rarely used it, unless farmers specifically request it. This is because when a few farmers used it themselves, after two or three days the water rebounded back. My approach is: first deal with the floating mud, then deal with the water. When the aerator has stirred for a night, the water is basically unbearably turbid. First broadcast Granule Spirit, turn off the aerator, then splash aluminum chloride. After this treatment, the water body is very clear and refreshing, and all floating dust is adsorbed to the pond bottom. Fertilize after 2 h. Based on 10 mu at 1 m water depth as the standard, mix and splash 3 buckets of Six-Resistance Algae-Culture Paste, 3 bags of enzyme calcium fertilizer, 5 bags of essence, and 10 kg urea. By the afternoon, the water body can basically turn green again, but the premise is that it must be a sunny day.

1.2.5 Handling foam
Foam is also a common problem at this stage. The cause of foam is algae aging. Large numbers of beneficial algae die, and the algae lose their decomposition and self-purification functions, so large amounts of foam are produced. To solve this problem, we must cultivate new algae to replace the aging algae. In this way, the problem is solved. Many farmers splash Ionic Calcium or raw oil, but this only treats the symptoms and not the root cause. Once the aerator is turned on, the foam comes back again.

1.2.6 Pond bottom smelling foul
Cause: There is a lot of bottom floating mud deposited year after year and much humus from various zooplankton, and dead algae rot, causing the pond bottom to smell foul. First use Water Purification King to detoxify, then splash Black Gold Spirit and powdered Live Bacteria King over the whole pond.

1.3 Late Stage of Farming (more than 50 days after stocking)

In the late stage of shrimp farming, water quality gradually tends to stabilize, with no major rises and falls. With continuous fertilization and bacterial supplementation, the water body generally becomes red water, soy sauce water, or dark green water.

We all believe red and soy sauce water are dangerous water colors and cannot be used to raise shrimp. But after observation and tracking, I found that as long as they are maintained properly, these two water colors can also successfully raise shrimp. The advantage of these two water colors is: no matter how the weather changes, they are very stable. After heavy rain, if you supplement some fertilizer and bacteria, their luster and fertility become very good. But many farmers do not like these two water colors and insist on adjusting them to dark green. Dark green is the ideal water color recognized by farmers.

To turn red water or soy sauce water into dark green, my approach is: for every 10 mu of pond at 1 m depth, first use 3 bottles of Water Purification King to detoxify, and two hours later mix and splash 7 bags of Nitrite Quick Knockdown, 7 bags of amino acid essence, and 7 bags of Flexible 100. Handled this way, it can basically achieve a dark green effect. However, the premise is that the shrimp must be over 60 days old.

In our work, we often hear farmers say that the pond pH is very low, and although they have splashed a lot of lime, it always cannot be raised, and the more they splash, the lower it gets. After splashing for a few days, the whole pond of water is ruined. This is because lime kills algae, so the more you splash, the lower it gets. If you splash lime for two consecutive mornings, but the pH in the afternoon is lower than the previous day, then do not blindly splash lime anymore. My approach is: crush the lime into lime granules, mix with calcium-magnesium-phosphate fertilizer, dry-broadcast it on the pond bottom, and then fertilize the pond, and this problem can be solved.

We often receive calls from farmers saying their pond water is very dense and transparency is too low, and they have used live bacteria many times but with no effect at all. If you encounter this situation, you must ask clearly whether it is dense or turbid. Some farmers often cannot distinguish dense from turbid. Dense is due to vigorous and excessive algae growth, while turbid is due to too much floating mud and no algae phase; in fact, it is lacking fertilizer. If it is turbid and you add bacteria, that is like adding frost to snow. The more you add, the more turbid it becomes, and finally it becomes muddy water. So when the water is dense, we use bacteria; when the water is turbid, we use fertilizer.

2 Common Problems in Shrimp Farming in Earthen Ponds

2.1 On deep-water feed trays and shallow-water feed trays, shrimp eat at different speeds. The causes are: on the one hand, in the early stage of farming, feed in deep water is eaten quickly and feed in shallow water is eaten slowly. This is because water transparency is high and shrimp are afraid of light, so they concentrate in deep-water areas, and naturally eat the feed quickly. On the other hand, in the late stage of farming, feed in shallow water is eaten quickly and feed in deep water is eaten slowly. This is because the bottom in deep-water areas is dirty, dissolved oxygen at the bottom is insufficient, and the shrimp all run to shallow-water areas. Therefore, in the late stage of farming, water depth is best controlled between 1.3-1.5 m.

2.2 For the reason shrimp suddenly eat slowly, first consider whether they have encountered sudden environmental changes causing stress. Second, whether the shrimp are molting.

2.3 Why shrimp are prone to disease when they eat a lot and grow quickly

When shrimp have been raised to 5-200 px, for a few days the shrimp increase feed very quickly, with each meal increased by 5-7.5 kg. Just after feeding to the 3rd day, the shrimp float up. The reason is that the shrimp eat too much, the burden on the liver, intestines, and stomach is too heavy, toxins accumulate too much in the body, causing metabolic disorder in the organism, and coupled with dissolved oxygen not keeping up, disease occurs. Once shrimp eat quickly, greatly exceeding the normal feeding speed, you must not increase feed too much at one time. For the noon meal, it is best to reduce feed by half.

2.4 Reasons shrimp liver turns yellow

In the early stage of farming, that is, shrimp below 100 px, their livers are mostly yellow. This is because they have not yet undergone liver transition. Just manage the water well and increase dissolved oxygen.
In the middle and late stages of farming, when dissolved oxygen at the bottom is insufficient and shrimp remain in a low-oxygen state for a long time, the shrimp liver turns yellow and gradually shrinks. If not handled in time, they float on the water surface. Handling method: in addition to maintaining good water quality, replenish external oxygen at night in time, and also supplement with liver-protecting products. Many farmers say their aerators run 24 h, so there should be no problem of insufficient bottom oxygen. Aerators cannot produce oxygen; they use water convection to dissolve a small amount of oxygen from the air into the water. There are many dissolved-oxygen dead corners in the pond that aerators cannot solve.

2.5 Shrimp stealth death

If it is early-crop shrimp and stealth death occurs within 20 days after stocking, farmers generally directly cull the pond and restock postlarvae. If it is late-crop shrimp and stealth death occurs within 20 days after stocking, farmers generally do not handle it and do not cull the pond, just leave it there and let it fend for itself. If shrimp stealth death occurs in the middle and late stages, it is basically liver shrinkage. Whether the shrimp are alive or already dead, after opening the head-thorax carapace and taking out the liver, if you feel it with your hand, there is no rebound at all, proving the liver has already shrunk very seriously. A few farmers believe it is poisoning from excessively high sulfite that causes stealth death. I believe that for shrimp over 60 days, more than 90% of ponds have high nitrite, and although many ponds have high nitrite, shrimp stealth death is not seen. Therefore, stealth death is because shrimp live in a low-oxygen state for a long time, and if not handled for a long time, or if the treatment effect is not ideal, the liver slowly shrinks. Once weather changes suddenly, such as high temperature and low pressure, shrimp begin stealth death. All stealth-dead shrimp are most numerous under the middle paddlewheel aerator, because dissolved oxygen is relatively high in this place, and these weak and sickly shrimp all run in this direction, so they all stealth-die here. Suggestion: adjust and maintain the water to an ideal state, and replenish external oxygen at night. Whenever handling stealth-dead shrimp, have farmers place a net under the middle paddlewheel aerator in the pond. Check it twice a day. If it increases day by day and is difficult to control, then you have no choice but to cull the pond.

2.6 Hypoxia

Generally, hypoxia can basically be solved with Degrading Spirit and Ionic Calcium. If the hypoxia is caused by the pond bottom heating up, you must add glucose, 2.5 kg per mu. Otherwise, the shrimp cannot sink down. There is another kind of hypoxia in which, after using various oxygen-increasing products, including Degrading Spirit and Ionic Calcium, and no matter how many aerators you add, it cannot be brought down. In this situation, you should quickly add water. If the tide level is not suitable, pump water with a pump, preferably adding 1250 px within 1 h. Adding water is also a method to quickly increase dissolved oxygen.
In Guangpo, every year a few farmers ask me what is a good substitute for Degrading Spirit, and I say there is no substitute. The role of Degrading Spirit is to improve the permeability of water, eliminate surface tension of the water body, make the oxygen in the water body form convection with oxygen in the air, and solve the problem of hypoxia. But it does not directly produce oxygen like Granule Oxygen, and using too much Granule Oxygen harms the water.

2.7 Under what circumstances shrimp can be saved, and under what circumstances they cannot

Shrimp floating on the water surface that are the smallest in the whole pond have more chances than dangers, and can be saved. Shrimp floating on the water surface with full intestines and full stomachs can also be saved. If the largest shrimp in the whole pond float up, those shrimp have more danger than chances, and it is best not to save them. Before using medication, you must cast a net to observe the shrimp liver, shrimp vitality, and body color, and only then can you decide whether to save them or not.

When observing the shrimp liver, remove the membrane covering the liver. The color of a normal liver is pork-liver color. If the liver is found to be red, it indicates the liver has already shrunk very seriously, and it is best not to save these shrimp. If it is red with a little green in it, this kind of liver indicates it has just begun to shrink, and in this situation you can consider saving them.


Author: Hainan Zhuoyue Biological Co., Ltd. Su Xiangjin