How to treat grass carp haemorrhage?

Grass carp haemorrhage is a kind of viral fish disease in the cultivation stage of grass carp fingerness. it has a wide epidemic area, long epidemic season, high morbidity, high mortality and great harmfulness. It mainly infects grass carp with a body length of 15 centimeters and a foot-old herring. The pathogen is aquatic reovirus, which belongs to the reovirus family. Let's take a look at how to treat grass carp hemorrhagic disease.

Prevalence of hemorrhagic disease of grass carp

1. Epidemic area: the epidemic season of grass carp hemorrhagic disease is from June to September, and it was first found in 1970. Since then, it has been prevalent in Hubei, Hunan, Guangdong, Guangxi, Jiangsu, Zhejiang, Anhui, Fujian, Shanghai, Sichuan and other major fish culture areas.

2. Harmful species: both grass carp and herring can get sick, but grass carp are mainly harmful to grass carp, ranging from 2.5 to 15 centimeters in size, and the mortality rate can be as high as 80%, and sometimes large grass carps over 2 years old also get sick. In recent years, due to the neglect of immunization, the incidence of grass carp virus disease is on the rise.

3. The water temperature of the disease: the water temperature was epidemic at 20-33 ℃, and the optimum water temperature was 20-28 ℃. When the water quality deteriorates, the dissolved oxygen in the water is low, the transparency is low, the oxygen consumption rate of total nitrogen, organic nitrogen, nitrite nitrogen and organic matter in the water is on the high side, the water temperature changes greatly, the fish body resistance is low, and the virus quantity is high. It also occurs when the water temperature is 12 ℃ and 34.5℃.

The pathogenesis of hemorrhagic disease of grass carp

Artificial infection of healthy grass carp takes 4-15 days from infection to morbidity and death, usually 7-10 days. The course of the disease can be divided into three stages: latent period, pretrending stage and developmental stage.

1. Incubation period: the incubation period of grass carp hemorrhagic disease is 3 to 1 days. During this period, the fish's appearance does not show any symptoms, and the activity and feeding are normal. The incubation period is closely related to water temperature and virus concentration, such as high water temperature, high virus concentration, short incubation period and long incubation period.

2. pre-trending period: the time before bleeding of grass carp is short, only 1-2 days, the body color of grass carp is dark and black, travel alone from the group, stop feeding.

3. Development period: the development period of grass carp hemorrhagic disease varies from 1 to 2 days, and the diseased fish show symptoms of congestion and bleeding.

Symptoms of hemorrhagic disease of grass carp

1. "Red muscle" type: tearing off the skin of diseased fish or aiming at sunlight or light to see through the fish, it can be seen that the subcutaneous muscles are congested, and in severe cases, the muscles are red, which is generally more common on smaller grass carp (body length 10 cm).

2. "wide red fin red operculum" type: the operculum, base of fin, top of head, mouth and orbit of diseased fish are obviously congested, which generally appear on larger grass carp species (body length more than 13 cm).

3, "enteritis" type: diseased fish intestinal congestion, often accompanied by loose scales, muscle congestion, various specifications of grass carp can be seen.

Prevention and treatment of hemorrhagic disease of grass carp

1. To inject or soak the inactivated vaccine or cellular attenuated vaccine against grass carp hemorrhagic disease.

2. Disinfectants such as chlorine dioxide and surfactant are sprinkled in the whole pool during the onset season.

3. Rhubarb or Scutellaria baicalensis antiviral Chinese herbal medicine was used in the whole pond, the dosage was 1 mg / L water body.

4. The water depth per mu is 1 meter. Make fine powder with 75 grams of honeysuckle, 75 grams of chrysanthemum, 375 grams of rhubarb and 225 grams of Phellodendron Phellodendri. Add 150 grams of salt and sprinkle it in the whole pool after mixing.

5. Every 100 kg of fish weight, beat into pulp with 8-10 kg of water peanuts, 500 g of garlic and 500 g of salt every day, mix in 3 kg of rice bran and feed for 5 days.

6. 10 kg of water peanuts per 100 kg of fish weight, mashed, mixed with 500 g of salt, 1 kg of rhubarb powder, 2 kg of leek or 500 g of raw garlic, and then mixed with rice noodles, wheat bran or duckweed 10 kg to make bait for 7 days.