Prevention and treatment of red body disease of Penaeus vannamei

Penaeus vannamei becomes "red body" after some diseases. Some shrimp farmers mistakenly think that the red body disease of Penaeus vannamei is Taura syndrome, but the drug treatment is not effective. However, the investigation found that Penaeus vannamei can show red body phenomenon in the case of sudden change of environment, infection of Taura syndrome and vibrio disease. Therefore, it is necessary to accurately identify the causes of red body symptoms of Penaeus vannamei.

Viral red body disease of Penaeus vannamei

First, stress red body:

When all kinds of physical and chemical factors in the water environment, such as water temperature, salinity, pH value, ammonia nitrogen, nitroso nitrogen, etc., the tentacles of Penaeus vannamei turn red, the tip of the tail fan turns red, and sometimes fishing and pesticide application will make the tentacles, tail fan and even appendages turn red. This phenomenon will disappear with the stability of physical and chemical factors such as water temperature and salinity in a short time. However, during the stress period, the anti-stress ability of shrimp decreased sharply, and it was easy to be infected by bacteria and viruses, followed by bacterial and viral diseases. The stress red body of Penaeus vannamei often occurs in summer.

Control measures: long-term use of clear water (Bacillus subtilis), photosynthetic bacteria and other microbial agents in ⑴ water to reduce ammonia nitrogen in water, regulate water quality, supplement various insufficient trace elements in shrimp, and improve disease resistance. Bioactive additives such as 0.1-0.2% biological enzyme active additives and 0.2-0.3% immune polysaccharides were added to the feed to improve shrimp immunity and enhance shrimp adaptability to the environment. Start the aerator immediately after ⑵ rainstorm, pay attention to the phenomenon of water stratification, and apply quicklime and so on. The amount of water replaced by ⑶ should not be too large, and the amount of water replaced each time should not exceed 10% of the total. When discharging and changing water, it is necessary to prevent excessive changes in water temperature, salinity, pH value and so on. After the changes of various physical and chemical factors of ⑷, appropriate medication should be used to prevent the disease, and non-irritating drugs should be selected, such as sprinkling with Qiangke 101or dibromohydantoin water in the whole pool.

Second, Vibrio parahaemolyticus red body:

The survey found that more than 75% of the red body phenomenon of Penaeus vannamei is Vibrio parahaemolyticus. The appendages of diseased shrimps turn red, especially swimming feet, the most obvious, also known as "red leg disease", often showing red all over the body. The activity of diseased shrimp weakens, swims slowly or does not move on the surface of the pool, sometimes rotates or swims vertically, slow to respond, loss of appetite or abstinence. The Gill of diseased shrimp is yellowish and the shell hardens. The degeneration of hepatopancreas was not obvious, and there were no black spots in shrimp. The morbidity and mortality of the disease are high, mostly in the high temperature and rainy season.

Control measures: clear the pond thoroughly before ⑴ stocking. In high temperature and rainy season, photosynthetic bacteria (5 grams per cubic meter) or clear water (0.25 grams per cubic meter) are applied regularly and sprinkled with 0.2 grams of dibromohydantoin water every 10 days. When the air temperature and water quality change greatly after ⑵ rainstorm, quicklime or dibromohydantoin should be properly used to maintain the stability of water body and reduce the stress response of shrimp. After the onset of ⑶, the whole pool was sprinkled with 0.2g QK101 chemical water per cubic meter. After sprinkling, start the aerator for 1-2 hours and use it again every other day. After 3-5 days, sprinkle every cubic meter with 0.3 grams of water and water in the whole pool. At the same time, 0.5 grams of fish Nicol, C1 grams of vitamins and 1.5 grams of biological enzyme active additives were added to each kilogram of feed for 3-5 days.

3. Viral red body:

Viral red body disease of Penaeus vannamei, also known as Taura syndrome, diseased shrimp shows red beard and red tail, especially the tail fan turns red, so it is also known as "red tail disease". Diseased shrimp body color tea red, little or no food, slowly swim on the water, die soon after leaving the water; diseased shrimp carapace becomes soft, easy to separate from muscle, diseased shrimp shell has irregular black spots, basically no red leg phenomenon, hepatopancreas degeneration or erosion, intestinal redness and swelling. Taura syndrome usually occurs 1-2 days after a sharp change in the water environment, and the disease is most severe in shrimp with a water temperature of 26-28 ℃ and 6-9cm. The water quality of the infected shrimp ponds is relatively strong, the transparency is usually in 20cm, the pH value is higher than 9, and the content of ammonia nitrogen per cubic meter of water is more than 0.5g.

Control measures: ⑴ stocking healthy seedlings. Clear the pond thoroughly before ⑵ stocking, and sprinkle it with 2-5g photosynthetic bacteria or 0.25g water once a week per cubic meter of water throughout the whole stage, especially after one month of shrimp fry stocking. At the same time, 2 grams of immune polysaccharides, 1 grams of biological enzyme active additives and 5 grams of white shrimp red body Xiao (plant antiviral protein) were added to each kilogram of feed, and fed 2-4 days every half month, twice a day; in the epidemic season, 0.2 grams of dibromohydantoin water was sprinkled in the whole pool every 10 days. After the onset of ⑶, every cubic meter of water was sprinkled with 0.2g Qiangke 101chemical water in the whole pool. After sprinkling, the aerator was turned on for 1-2 hours and used again every other day. After 3 days, the whole pool was sprinkled with 0.4g clear water and 5g activated zeolite plus water per cubic meter of water. At the same time, 15-20 grams of white shrimp red body Xiao, 1-2 grams of biological enzyme active additives, 2-3 grams of stable vitamin C and 10-20 grams of fish oil were added to each kilogram of feed for 5-7 days, twice a day.