First, white body disease
Pathogen: Qian Dong et al. Research Institute of Zhejiang Provincial Institute of Freshwater Fisheries was identified as Macrobrachium novae.
The main symptom of the disease is to turn white. At the beginning of the disease, some small white spots appeared in the diseased shrimp, which then expanded from back to front. The abdominal muscles appeared white and turbid, and even the entire shrimp body was white except for the head. At the early stage of disease, most of the diseased shrimp were still able to ingest food and clam shells, but gradually weakened their activities and decreased their food intake. If they were not treated in time, the mortality rate was relatively high.
Popularity: The disease is a new disease in our city in recent years. It continues every year; the most serious disease is in 2001, with an area of ​​15,000 mu, accounting for about 30% of the total aquaculture area in the current year. The onset time is usually from April to June every year, especially in the plastic greenhouses to raise the temperature of the juveniles; in the middle and late May, when the juveniles are magnified, the condition gradually improves. The disease is mainly brought in by shrimp seedlings, so it is very prudent to purchase shrimp seedlings.
Control methods: Internal and external use simultaneously. External use of sterilization, generally alternate use of iodine preparations and chlorine preparations; after 1 time, every 3 to 5 days can be used again. Oral medicine, combined with Western, acute attack with antibiotics added 2 to 5 grams per kilogram of feed, Chinese herbal medicine added 10 grams per kilogram of feed, treatment for 5 to 7 days. The course of the disease is longer. Generally after one episode of treatment in acute attack, it is still necessary to control the drug more than one course of treatment. At this time, the medication is the same as the prophylactic drug. 10 to 15 grams of Chinese herbal medicine is added per kilogram of feed (radicalin, three yellow powder, etc.) . Uniformly processing baits in feed mills, shrimp farming households is extremely convenient to use, and the control effect is relatively satisfactory. The general control efficiency is over 90%.
Second, vibriosis
Pathogen: Vibrio parahaemolyticus.
Sick shrimps are emaciated and swim alone. They are slow to move. They sometimes swim on the surface of the water, sometimes crawling on the edge of the pool, and are severely immobile, eating less or stopping feeding. The disease is characterized by a reddening of the body and appendages. The diseased shrimps first became red on foot, swim foot, tail fan, etc. In severe cases, the body was pale red and the mortality of the disease was high.
Popularity: The disease has continued to develop in our city in recent years. The onset time is generally from April to June every year. The incubation period is mainly based on warming plastic sheds to raise larvae, especially when the shrimps enter the pool 15 days before entering the pool.
Control methods: Pool water is sterilized with dibromohydantoin, povidone-iodine, and other drugs; at the same time oral administration of antibiotics, Vc, biological enzymes and other baits for 3 to 5 days. Once the disease is treated in time, the effect is good; once the disease is heavy, the diseased shrimp is anorexia or even stops feeding, and the therapeutic effect is difficult to guarantee.
Third, black shank disease
Pathogens: Generally caused by bacterial and fungal infections, and the lack of vitamin C in foods can also cause the disease.
In the early stages of disease shrimp, it was orange or bright brown, gradually turned dark and eventually became black, so it was called black shank disease.
Epidemic: The disease occurs in large numbers every year, and the onset time is usually in the middle and late stages of culture.
Control methods: regular water disinfection and prevention, once the disease, pool water with dibromohydantoin, chlorine dioxide and other drugs disinfection, while taking oral antibiotics, Vc and other baits for 3 to 5 days, the general treatment effect is good.
Fourth, black shell disease
Pathogens: The exact pathogen is not known.
Shrimp shrimp shell black, especially in the chest chest, appendages, tail fans, etc. more obvious. Generally it is brownish, dark, first and later, and lighter and heavier. In severe cases, most shrimps are black.
Popularity: The disease is a newly occurring disease. In 2004, a large area of ​​outbreaks occurred, with an area of ​​more than 30,000 mu, and the onset time was mainly in the middle and later stages. The disease seriously affects the oyster shell and growth of Macrobrachium rosenbergii, and it also affects the quality and sales of adult shrimp. Generally, it can only be processed into shrimp, and the price is about 20% lower than that of normal shrimp.
Control methods: In 2004, we selected 16 nursery stocks to conduct tests on the control effects of commonly used fish medicines on black shell disease of Macrobrachium rosenbergii. The results showed that: After feeding the shrimp into the clear water pond, the black shell shrimp no longer turned black after using the no-drug, and the black shell shrimp in the original disease pond continued to grow black after a few days. It can be seen that the disease is mainly caused by the environment. Practice has also shown that shrimp ponds of the same type have many silt and poor water quality; shrimps with high levels of ammonia nitrogen, nitrite, and hydrogen sulfide, and fewer phytoplankton have more disease incidence and heavier disease. Preventive work is mainly to repair shrimp pond environment and fertilize the water quality, reduce, reduce the occurrence of diseases; thorough and effective prevention and control methods need further study and exploration.
V. Fulminant shrimp disease
Pathogens: The exact pathogens to be investigated may be caused by cross infection between viruses and bacteria.
The sick shrimps are on the side, lying sideways, and the large soft shelled shrimp are mostly. There was no traumatic body surface and there was no obvious morbidity. A few of the diseased shrimp had green algae attached, and the muscles were turbid. A 20- to 30-mu shrimp pond, the death rate ranging from a few pounds to several tens of pounds, more than a hundred pounds. Strong stress response, once the net, large water change, the use of disinfectants, sudden increase in temperature, etc., the increase in death.
Popularity: The disease is a new outbreak of shrimp disease in 2005, the peak period of the city's incidence of more than 10,000 acres, Jiangdu disease is more serious than the city.
Control methods: 1 alternate disinfection with iodine and chlorine preparations; 2 internal antiviral, bacterial baits, Chinese herbal medicine control effect is ideal. High-dose Chinese herbal medicine Quanchiposa has a good effect on shrimp ponds with severe disease and less feeding. 3 Control and improve the quality of shrimp pond water after biological control.
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