Control techniques of erythrosomiasis of Penaeus vannamei

2022-05-26 0 By

Litopenaeus Vannamei is a South American white shrimp (Litopenaeus Vannamei), which belongs to penaeidae and Litopenaeus genus.With the characteristics of fast growth and strong disease resistance, it is the leading shrimp breed in Wuxunzhen, Binhai County.In recent years, with the increase of aquaculture scale and density, shrimp diseases occur frequently, especially erythrosomiasis, which is the most common and harmful disease.According to the cultivation practice, the prevention and control techniques of erythrosomiasis of Penaeus vannamei are introduced as follows.1 Stress erythrosome 1.1 Symptoms When pond water temperature, dissolved oxygen, salinity, ammonia nitrogen, nitrite and other indicators, under the influence of typhoon, heavy rainfall and other factors mutation, penaeus prawn tail fan red, red tentacles and other symptoms, water change, fishing, drug application will also produce similar stress response.1.2 Prevention and Control Measures (1) If the water needs to be changed, it should be carried out slowly, and the water should not exceed 1/3 of the total water in the pool within 1 day.(2) ρ (dissolved oxygen) >4 mg/L, pH 7.5-8.5, ρ (nitrite) 2 viral erythrosomes 2.1 Acute stage of symptoms: the body surface of Vannamei vannamei was pale red, the caudal fan and swimming foot showed obvious red, and the epithelium of swimming foot or caudal foot showed focal necrosis.Transitional period: there are many random and irregular lesions on the surface of carapace.Chronic stage: no obvious symptoms.2.2 Prevention measures (1) Thoroughly disinfect the pond before stocking.(2) After the onset of the disease, dibromohynin or compound iodine should be used for disinfection once every 1 day, for 2-3 times.(3) Use bacillus, photosynthetic bacteria, super cool bottom modification to regulate and improve water quality, and use it stagger with disinfectant.(4) Add compound immune polysaccharide and vitamin C according to 0.1%~0.2% of the diet.3 Bacterial erythema 3.1 The main symptoms are redness of appendages, especially the swimming foot, which is often referred to as “red leg disease”.The activity of the diseased shrimp is weakened, and they swim slowly or immovably on the pond side or water surface, sometimes rotating or vertical swimming, with slow reaction, loss of appetite or stop eating.The gills of the diseased shrimp were pale yellow, the shell became hard, the variation of hepatopancreas was not obvious, and the body had no symptoms of black spots.Hemolymph becomes thinner, blood cells become less, coagulation is slow or non-coagulation.3.2 Preventive measures (1) Thoroughly disinfect the pond with quicklime or bleaching powder before stocking.(2) The amount of bait should be appropriate, the bait should be fresh, and the amount should be reduced after the disease.(3) Regular application of bacillus, photosynthetic bacteria, super cool bottom modification to regulate and improve water quality.(4) After the onset of the disease, “xiaoculing” was applied to kill vibrio and other harmful bacteria, once a day, for 2-3 days.(5) Enrofloxacin and vitamin C were fed with 0.1% to 0.2% of the diet for 3 to 5 days.