Control Methods for Taura Syndrome in Whiteleg Shrimp
Taura syndrome is caused by infection with Taura syndrome virus, also known as red body disease (typically, viral infection causes the body to turn red while the appendages do not; bacterial infection causes the appendages to turn red while the body does not; when both the body and appendages turn red, it may be a mixed infection). Sick shrimp stop feeding, swim slowly at the water surface, have a softened carapace, a reddened body color, and an empty stomach. Microscopic examination reveals dispersed body pigments, and large numbers of necrotic areas distributed in a scattered-egg pattern can also be seen in the epithelial tissue. The gills are yellow and swollen, and some have white spots on the carapace.
Control methods:
1. Stock healthy, high-quality seed stock: fry measuring 0.8-1.0 cm, with a semi-transparent body, full and sturdy musculature, and strong swimming against the current; the water temperature in the nursery pond is best kept below 30 degrees.
2. Reasonable stocking density: for semi-intensive culture ponds, a stocking density of 10,000-30,000 is suitable; for intensive culture ponds, a stocking density of 40,000-80,000 per mu is suitable; for high-level ponds (high-density intensive culture ponds), a stocking density of no more than 120,000 per mu is suitable.
3. Culture only when the water temperature is relatively high. If there is no heat-preservation greenhouse, it is better to stock in May when the water temperature rises above 25 degrees.
4. Maintain good water quality: the daily fluctuation range of salinity should be below 0.5%, the daily fluctuation range of pH (7.8-8.6) should be below 0.5, dissolved oxygen should be maintained above 4 mg per liter, ammonia nitrogen below 0.02 mg per liter, nitrite below 0.01 mg per liter, and water transparency at 40-60 cm.
5. Drug control: on the first day, apply 133 g of super-iodine quaternary ammonium salt per mu per meter of water depth by broadcasting over the entire pond; on the second day, continue to apply 133 g of super-iodine quaternary ammonium salt per mu per meter of water depth by broadcasting over the entire pond; on the third day, apply 200 g of dibromohydantoin per mu per meter of water depth by broadcasting over the entire pond. On the sixth day, apply 200 g of Bacillus subtilis and 13,340 g of zeolite powder per mu per meter of water depth by broadcasting over the entire pond. At the same time, add 2 g of immune polysaccharide, 15 g of Hongtixiao, 10 g of fish oil, and 2 g of vitamin C per kilogram of feed, and feed the medicated bait twice a day, morning and evening, for 6 consecutive days.