CATDOLL : CATDOLL: What are the disease prevention techniques for whiteleg shrimp in Shunde area?

"Death stealing syndrome"

It is also called "dead bottom disease" or "bottom out". As the name suggests, most shrimps die at the bottom of the pond. Dead shrimps usually have no obvious abnormal symptoms. The muscles of shrimps that have just died are turbid white. Some dead shrimps have yellow or black gills, and some have soft shells. "Stealing death disease" is a chronic poisoning caused by nitrite. As the breeding time increases, the residues at the bottom of the pond, such as leftover bait, organic matter and shrimp excrement, accumulate more and more, which is easy to breed bacteria. Moreover, the decomposition of these residues consumes a lot of oxygen, causing hypoxia at the bottom of the pond, and easily produces harmful substances such as nitrite and sulfur dioxide, causing shrimps to be poisoned and die one after another.

Prevention methods

Judging from the characteristics of the disease, the main reason is that in recent years, shrimp farmers in Shunde area have blindly pursued production and increased the amount of seedlings, but the management technology and equipment have not kept up. In the middle and late stages of aquaculture, the water body is often in a state of insufficient dissolved oxygen, and even causes hypoxia or local oxygen. Hypoxia can easily cause water quality to deteriorate, and ammonia nitrogen and nitrite are not decomposed smoothly and are high. Therefore, according to the management level, farm environment and equipment conditions, the stocking density should be controlled to prevent shrimp from "death". The management work mainly includes: controlling the breeding density; controlling the amount of feed to reduce residual feed. For oxygenation, insist on turning on the machine for 2 to 3 hours every morning and noon. In low-pressure and hot weather, appropriately extend the oxygenation time, and it is best to turn on the aerator at night and also put in oxygenators to keep the dissolved oxygen in the pool water at 4 mg/L. Improve water quality. Apply an appropriate amount of zeolite powder at ordinary times. Add 0.2-0.3 mg/L of Bacillus, photosynthetic bacteria or 1-1.5 mg/L of EM bacteria every 7-15 days. After 40 days of seedlings, start to add nitrifying bacteria at 0.2-0.3 mg/L. Change water in small amounts and multiple times. It is best to change 1/3 of the pond water every week. The water quality should be good. If you find that the shrimp are "dead at the bottom", you should first drain about 10 cm of the bottom pond water, then add an equal amount of new water, and at the same time turn on the aerator and add oxygen.

Black gill disease

This is mainly because the shrimp pond bottom is seriously polluted by organic matter, leftover bait and shrimp excrement, which deteriorates the water environment. In addition, weather changes such as heavy rains cause great stress to shrimps, weakening their resistance and making them susceptible to bacterial infection. The diseased shrimps eat less, their gills swell and turn black, and a large number of Vibrio and filamentous bacteria can be observed under a microscope.

Precautions

It is basically the same as "stealing death syndrome". Usually, add 0.2% stable vitamin C to the feed and strengthen water quality management. When the disease is found, the bottom pool water should be drained immediately about 10 cm, and the whole pool should be sprayed with 2-3 mg/L of Sanisol solution or 1.2-1.5 mg/L of Lebitol disinfectant solution, and the aerator should be turned on at the same time. The next day, 5 kg/mu of bottom improver (the main ingredient is zeolite powder) should be applied to the shrimp pond. On the third day, add an equal amount of new water into the pond, and then apply microbial agents to regulate the water quality.

Viral white spot disease

Shrimp are highly stressed by weather changes such as heavy rains, and are more susceptible to viral white spot disease when their resistance is weakened. The disease has occurred in some breeding areas in Shunde, but has not yet caused large-scale losses in Shunde. However, this is a disease that once brought a devastating blow to the shrimp farming industry. There is no good specific medicine, and prevention is the main thing, because once the disease occurs, all the shrimp in the pond will die quickly, and the virus spreads very quickly. Early detection can be controlled with drugs, but if it is too late, the only thing to do is to disinfect the entire pond and drain it away, and then release a batch of seedlings after strict disinfection. Therefore, Shunde's shrimp farmers are reminded to take early prevention measures, and the water used for breeding must be strictly disinfected before entering the pond. The wastewater from farms where shrimp diseases have broken out must be disinfected before being discharged, so as to avoid spreading to other farms through wastewater.

Prevention methods

The chest and abdomen of the infected shrimp often have white or dark blue spots. In the later stage of the disease, white spots or softening of the shell, cephalothorax and appendages appear under the skin of the shrimp, and the cephalothorax is easy to peel off, and the shell and dermis are separated. Prevention mainly starts from prevention. The specific methods are: add 0.2% stable VC and other drugs that can enhance physical fitness to feed; every 5 to 7 days, spray the whole pond with 0.5 to 0.6 mg/L bromine chloride hydantoin; every 15 days, spray the whole pond with 1.5 mg/L quaternary ammonium salt complex iodine; apply microbial preparations in appropriate amounts to maintain the stability of the water environment.

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

Frequently use compound bacteria to adjust water to prevent the accumulation of harmful substances in the bottom. While adjusting water, use Xuxuqing's "Di Sushuang" to improve the bottom at intervals to inhibit the excessive reproduction of harmful bacteria and prevent the occurrence of ciliate disease.

When preparing for breeding celery, you should pay attention to the prevention of diseases, pay attention to the replacement of water sources, pay attention to the disinfection and filtration of water sources, pay attention to the clarity of the water source, and pay attention to the soil in it.

Change water, insist on small amounts and multiple times, it is best to change 1/3 of the pool water every week, the water quality should be good. Control the density of breeding in spring; control the amount of feeding to reduce residual bait. Aeration, insist on turning on the aerator for 2-3 hours every morning and noon. In low-pressure and hot weather, appropriately extend the aeration time, and it is best to turn on the aerator at night and also put in oxygenators to keep the dissolved oxygen in the pool water at 4 mg/L.