Detailed Explanation of Seven Issues in Water Quality Regulation for Whiteleg Shrimp (Litopenaeus vannamei) Farming
1. Can water disinfection and probiotics be used at the same time?
AquacultureThe "raw water" for farming must be disinfected when entering the pond, water quality deterioration requires disinfection, disease outbreaks require disinfection, and algal crashes require disinfection. The purpose of disinfection is to kill pathogenic bacteria, viruses, and harmful insect eggs, creating conditions for establishing a high-quality microecological environment in the aquaculture water. If the interval between disinfection and the introduction of probiotics is too long, not only is the purpose of disinfection not achieved, but conditions for an outbreak of pathogenic bacteria or viruses are created instead, because the microecological function of the disinfected water is almost blank, and the pathogenic microorganisms that have not been killed and those floating in the air will rapidly occupy the blank. Before this happens, microecological preparations of probiotics unaffected by disinfectants must be introduced as quickly as possible to inhibit the expansion of harmful microorganisms. When using different disinfectants, special attention should be paid to matching them with different microecological bacterial preparations. Long-term experiments have proven that commonly used disinfectants in aquaculture, such as trichloroisocyanuric acid, sodium dichloroisocyanurate, povidone-iodine, one-component chlorine dioxide, and bleaching powder, have no major impact on Bacillus subtilis, Bacillus amyloliquefaciens, Paenibacillus polymyxa, and Lactobacillus plantarum, and can be applied simultaneously with disinfection. Bleaching powder has no effect on Rhodobacter sphaeroides (Hongjunbao), and potassium monopersulfate disinfectant has no effect on any of the above probiotics. It is recommended to use potassium monopersulfate disinfectant (Weike) simultaneously when applying microecological preparations for better disinfection results.
2. How to fertilize water quickly and with long-lasting effect?
In aquaculture, the purpose of water fertilization is to cultivate algae. The purpose of cultivating algae is to utilize the "three nitrogens" in the water, along with the metabolic products and residual feed of fish, shrimp, and crabs, to increase dissolved oxygen levels in the water and optimize the ecological balance of the three-pole cycle (farmed organisms - aquatic plants - microorganisms). In addition to the basic nutrients needed for aquatic plants, applying an appropriate amount of probiotics will make aquatic plants grow faster and more stably. Research has proven that applying a small amount of Bacillus amyloliquefaciens and Paenibacillus polymyxa, combined with Rhodobacter sphaeroides (Hongjunbao), will keep aquatic plants growing healthily. The principle is that the superoxide dismutase (SOD), 5-aminolevulinic acid, vitamins, and active enzymes metabolized by these bacterial groups help the photosynthetic growth of algal communities and the absorption and utilization of decomposition products of low-grade fatty acids and "miscellaneous proteins," stabilizing the water ecology for a longer period.
3. How to rapidly degrade ammonia nitrogen?
Microbial preparations all have varying degrees of ability to utilize ammonia nitrogen for growth. To rapidly degrade ammonia nitrogen, strains with strong nitrogen-source utilization must be combined. Bacillus subtilis, Bacillus amyloliquefaciens, Paenibacillus polymyxa, and Rhodobacter sphaeroides have good ability to utilize ammonia nitrogen for growth. It is recommended to use Bacillus subtilis + Bacillus amyloliquefaciens + Rhodobacter sphaeroides (at a ratio of 1:1:2), with a dosage of 2-4 kg/mu, combined with SOD biological substrate modifier or Yayuanxiaosu substrate modifier at 2 kg/mu, applied once every 10 days, which can maintain ammonia nitrogen levels at safe values long-term.
4. How to degrade nitrite?
Nitrite produced in aquaculture water is an intermediate product of the conversion of ammonia to nitrate. Due to excessive accumulation of residual feed and feces in aquaculture ponds, ammonia nitrogen is continuously produced. Combined with the inherent laziness of nitrifying bacteria and their pickiness about metabolic conditions, when temperatures are relatively low, the algal phase is unbalanced, or oxygen supply is insufficient, the metabolism of nitrifying bacteria slows down, causing nitrite accumulation in the aquaculture water to rise. Ammonia nitrogen, nitrate, and nitrite are all nitrogen sources with different compositions and can actually be utilized by different microbial groups. Given the biological characteristic that most microorganisms require nitrogen sources for growth and metabolism, releasing combinations of different probiotic groups is very effective for degrading nitrite in aquaculture water. The method for degrading nitrite is: Paenibacillus polymyxa 2 kg/mu + polysaccharide lactic acid bacteria 2 kg/mu + fertilizershui essence 1 kg/mu as a combination (use this amount when nitrite is below 1 mg/L; increase the amount when above 1 mg/L), splashed once across the entire pond, which can reduce it to a safe value within 2-3 days. Then use Yayuanxiao biological substrate modifier for long-term control. Suitable for both freshwater and seawater aquaculture ponds.
If nitrite in the aquaculture pond is too high, first splash Heitujing across the entire pond. After an interval of 2-4 hours, splash Xiaohuabao across the entire pond at a dosage of 500-1000 g/mu. This method takes relatively long to show results, but once nitrite is degraded, the effect is long-lasting.
5. How to prevent or control algal crashes?
Inorganic nutrients being too low in the water, excess organic nutrients, reduction of precursor bacterial groups that decompose nutrients, and high temperatures with frequent rain are all factors that trigger algal crashes. They are also high-risk stages in aquaculture. Large amounts of algal toxins are also continuously produced in alternating cycles, leading to diseases such as pancreatic lesions, empty intestines and stomachs, and enteritis. It is necessary to promptly supplement inorganic nutrients (such as calcium, phosphorus, magnesium, etc.), along with precursor bacterial groups + a small amount of algal seeds, and new algal communities can soon be cultivated. However, it should be noted that after an algal crash, regardless of the algal type, algal toxins will be produced, and these algal toxins will damage the liver and pancreas and intestines of farmed species to varying degrees, causing diseases. The prevention method is: after an algal crash, first splash Gaosheng 100 Type A and Type B at 500 mL/mu each, once daily for 3 consecutive days. Then splash Fuyiduo 1-2 kg/mu + Yingjibao 1 kg/mu + Hongjunbao 2 kg/mu (note: increase aeration).
6. How to remove foamy oily substances on the water surface?
Due to excessive organic matter such as residual feed and feces in the water, or algal crashes, large amounts of foam appear on the pond water surface, or yellowish-brown oily substances accumulate, causing the water quality to become foul-smelling and oxygen-deficient. Use Fuyiduo 2 kg/mu + Bacillus amyloliquefaciens 2 kg/mu, combined with polysaccharide lactic acid bacteria 2 kg/mu. After improvement, splash Yayuanxiao 2 kg/mu.
7. How to deal with stress responses in aquatic animals?
Modern biological research has proven that stress responses cause sustained elevation of adrenaline and cortisol in shrimp, promoting protein breakdown in the body, accelerating fat oxidation, and causing metabolic disorders. Sustained elevation of cortisol after stress triggers immune suppression. When the immune system is balanced, pathogens are suppressed by healthy immune cells and are unlikely to cause disease. Once the immune system cannot function normally, pathogens latent in the body can activate, causing disease or acute death. Therefore, stress regulation is the key to protecting immune mechanisms. Methods: (1) Regularly use Gaosheng 100 mixed into feed for feeding, and splash biological Yingjibao 1 kg/mu + Hongjunbao 2 kg/mu, which has a very good effect on regulating stress. (2) Use trimethylglycine (betaine) for anti-stress; typically, splashing 250 g of Yingjibao per mu of water (1 m deep) is sufficient.
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