What are the disease prevention techniques of Penaeus vannamei in Shunde?

Also known as "bottom-dead disease" and "bottom-broken disease", as the name implies, most shrimps die at the bottom of the pond. Dead shrimps generally have no obvious abnormal symptoms. The muscles of newly dead shrimps are white and turbid, some dead shrimps can see yellow or black gills, and some can see soft shell phenomenon. Stealing death is a chronic poisoning caused by nitrite. With the increase of culture time, residues such as residual bait, organic matter, shrimp manure and so on at the bottom of the pond accumulate more and more, which is easy to breed germs. The decomposition of these residues consumes a lot of oxygen, resulting in hypoxia at the bottom of the pond, which is easy to produce harmful substances such as nitrite and sulfur dioxide, leading to shrimp poisoning and death.

preventive

Judging from the characteristics of the disease, the main reason is that shrimp farmers in Shunde area have blindly pursued output in recent years, increased the amount of seedlings released, and management technology and equipment failed to keep up. In the middle and late stage of aquaculture, the dissolved oxygen in water is often insufficient, even resulting in hypoxia or local hypoxia. Lack of oxygen can easily lead to deterioration of water quality, with poor and high decomposition of ammonia nitrogen and nitrite. Therefore, the stocking density should be controlled according to the management level, environment and equipment of the farm to prevent shrimp from "dead bottom". Management work mainly includes: controlling breeding density; Control the feeding amount and reduce the residual bait. Oxygen-increasing: Turn on the machine for 2-3 hours every morning and noon, and appropriately extend the oxygen-increasing time in low-pressure and sultry weather. At night, it is best to start the aerator and add the aerator to keep the dissolved oxygen in the pond at 4 mg/L. In order to improve the water quality, an appropriate amount of zeolite powder is usually added, and 0.2-0.3 mg/L Bacillus, photosynthetic bacteria or 65,438+0-65,438+0.5 mg/L EM bacteria are added every 7-65,438+05 days. When prawn "dead bottom" is found, we should first release about 10 cm of water in the bottom pond, then add the same amount of fresh water, and at the same time add an aerator and put it into an oxygenator.

Black gill disease

The main reason is that the organic matter, residual bait and shrimp manure at the bottom of the shrimp pond are seriously polluted, which makes the water environment worse. In addition, weather changes, such as the stress of prawns after heavy rain, weaken their resistance and are easily infected by bacteria. The consumption of diseased shrimp decreased, and the gills became swollen and black. A large number of vibrios and filamentous bacteria can be observed under the microscope.

preventive measure

Generally, it is the same as "stealing death". Usually, 0.2% stable vitamin C is added to feed to strengthen water quality management. Immediately after finding the disease, drain the water of about 10 cm from the bottom pool, spray 2 ~ 3 mg/L of bromogeramine solution or 1.2 ~ 1.5 mg/L of Lebaiduo disinfectant on the whole pool, and start the aerator at the same time. The next day, 5 kg/mu of substrate improver (mainly zeolite powder) was applied to the shrimp pond. On the third day, the same amount of fresh water was added to the pool, and then microbial agents were applied to control the water quality.

Viral leukoplakia

The weather changes, such as the stress of shrimp after heavy rain, and the virus white spot disease is easy to occur after the shrimp's resistance is weakened. The disease has occurred in some breeding areas in Shunde, and has not caused large-scale losses in Shunde yet. However, this is a disease that once brought a devastating blow to the shrimp industry. There is no good specific medicine, mainly in prevention, because once the shrimps in the whole pond die quickly, the virus spreads very quickly. If found early, it can be controlled by drugs. If it is late, only the whole pond shrimp can be disinfected and released, and a batch of seedlings can only be released after strict disinfection. Therefore, shrimp farmers in Shunde must be reminded to take preventive measures as soon as possible, and the aquaculture water must be strictly disinfected before entering the pool. However, the wastewater from the farm where shrimp disease broke out must be disinfected before it can be discharged, so as not to spread to other farms through wastewater.

preventive

There are often white or dark blue spots on the chest and abdomen of sick shrimp. In the late stage of the disease, white spots or crustaceans appear on the subcutaneous, crustaceans and appendages of shrimp, and the head and breastplate are easy to fall off, and the shell is separated from the dermis. Prevention mainly starts with prevention, and the specific methods are as follows: adding 0.2% stable VC and other drugs that can enhance physical fitness; Every 5 ~ 7 days, use 0.5 ~ 0.6 mg/L bromochlorohydantoin to splash in the whole pool; Every 15 days, the whole pool is sprayed with 1.5 mg/L quaternary ammonium salt; Proper application of microbial agents to maintain the stability of water environment.

In short, management should be strengthened in the process of breeding, especially with the arrival of high temperature weather in Shunde and surrounding areas and rainy and sultry weather in summer, farmers should not relax in management, and should take precautions early, find problems early and prevent them early.