First, the onset time and symptoms of rotten skin syndrome, the disease is most likely in the low water temperature period from 65438+February to March of the following year. The characteristics of the disease are as follows: first, the incidence range is wide, affecting all aquaculture areas; Second, the onset is fast. Once the disease quickly spreads to the whole pool, the mortality rate can reach more than 90%, which can cause great economic losses. The main clinical symptoms are shaking head, blowdown, swelling of mouth, inability to contract and close. With the aggravation of the disease, the number of diseased ginseng ulcers increased, forming blue-white spots, whole body ulceration and autolysis, which led to the death of sea cucumber and dissolved into snot-like colloid, leaving some white marks on the attachments.

Second, the etiological analysis of rotten skin syndrome Etiology 1: It is caused by the pollution and poisoning of sea cucumber's own feces and residual bait. The main cause of this disease is bacterial infection, often accompanied by secondary infection of mold and parasites. There are different types of pathogens in different regions, that is, pathogens are regional and diverse. As we all know, sea cucumber is a benthic organism, which lives in the bottom of aquaculture ponds for a long time, and bacteria, viruses and parasites are only concentrated in the bottom of ponds. At the same time, the ginseng pond is also the place with the highest concentration of hydrogen sulfide, ammonia nitrogen, nitrite and harmful substances, especially the pond where ginseng has been planted for many years. After the manure, residual bait, macroalgae and seaweed in the pond rot, deep sediments are formed at the bottom of the pond, which is easy to cause local hypoxia at the bottom of the pond. In addition, sea cucumber moves slowly, has the habit of sleeping and hibernating in summer, and cannot escape from the bad environment quickly, which makes sea cucumber live in a polluted and polluted environment for a long time. Hydrogen sulfide is a compound that causes the sea cucumber to stop breathing and die. It is a combination of suffocation and irritation. It is colorless and smelly, and the most sensitive tissue to its toxic effect is the contact part of the brain mucosa of sea cucumber. Hydrogen sulfide is mainly produced by protein decomposition. Sludge and organic matter in sewage will produce hydrogen sulfide. When the water contains 0.5 mg/l of hydrogen sulfide, it will cause acute poisoning of aquatic animals, and when it is higher than 0. 1 mg/l, it will cause chronic poisoning. Over time, it will invade the sea cucumber and reduce its resistance, thus causing the harm of microorganisms such as bacteria, viruses and parasites. When the weather suddenly turns cold or warm, it will lead to the outbreak of sea cucumber.

Reason 2: It is caused by the death of algae in the pool. Due to the suitable temperature and rich nutrition, a large number of algae often grow in the sea cucumber culture pond. Some of these algae are plankton and some are benthic algae. These algae have dual functions in sea cucumber culture. First of all, shade can reduce the temperature of pool water in high temperature season, which is beneficial to the safety of sea cucumber in summer; The second is to absorb the harmful substances in the pond and the bottom of the pond, reduce the damage to sea cucumbers and increase the dissolved oxygen in the pond water. However, it has great shortcomings. When the water temperature gradually decreases, algae will die in large numbers, sink into the bottom of the pond to rot and deteriorate, and will breed a large number of microorganisms such as bacteria and viruses. When the water temperature drops, the immunity of sea cucumber is in decline because there is no oxygen-increasing and absorption function of algae in the pond, so it is inevitable that sea cucumber will get sick.

Reason 3: Due to the weakness of sea cucumber. As we all know, the incidence of sea cucumber growing in natural sea areas is very low, mainly because it can absorb various nutrients, especially unpolluted foods containing various vitamins and trace elements in nature, so that it can always maintain a nutritional balance in its body, thus having strong disease resistance. But the sea cucumbers cultured in ponds are different. Due to the high stocking density and narrow range of activities, the vitamins and trace elements that can be absorbed are limited, especially the substances that are most beneficial to the growth of sea cucumbers in natural waters, which can not be absorbed into the body in time, resulting in nutritional imbalance of sea cucumbers. Coupled with the low temperature in winter, sea cucumbers stop eating, and weak bodies create invasion conditions for bacteria and viruses. For example, the lack of vitamin C in sea cucumber will directly lead to the disorder of biological oxidation process and the decrease of anti-toxicity, making it difficult for the body to cope with various stress reactions, thus causing tissue lesions.

Reason 4: Insufficient dissolved oxygen in the pool. The habitat environment and conditions of sea cucumbers growing in natural sea areas are quite different, especially when the temperature is lower than the water temperature in winter and spring, and when the temperature gradually exceeds the water temperature, the surface water temperature is high and the bottom water temperature is low, and the water temperature in the pool is stratified. Due to the small tidal range in winter, limited water circulation, toxic substances and residual bait pollution produced by sea cucumber feces and a large number of algae die and rot, resulting in the formation of anoxic and anaerobic zones at the bottom of the pond, which leads to the decline of metabolic functions of sea cucumber's physical fitness, nerves, digestive and excretory systems and the decline of disease resistance. It is not difficult to understand that sea cucumber has rotten skin.

Third, the "secret" of prevention and treatment of old Yin Jiahai Shen

According to the etiological analysis of sea cucumber rot syndrome, through investigation, analysis and demonstration, the author thinks that only by effectively controlling the pollution at the bottom of the pond, adding Chinese herbal medicine, Vc and other vitamins to the feed and improving the immunity of sea cucumber are the effective ways to prevent and treat sea cucumber rot syndrome.

Tip 1: Put zeolite powder, activated carbon, clay, medical stone, etc. Put it into the culture pond regularly, and the dosage per mu is 65,438+000 ~ 65,438+050. Using the micropores of minerals to adsorb microorganisms and toxic substances such as ammonia nitrogen and hydrogen sulfide in aquaculture water and pathogens harmful to the growth of sea cucumbers in aquaculture ponds and sediments can alleviate the deterioration of water quality and reduce the pollution degree at the bottom of ponds.

Tip 2: Put 20-30 ㎏ lime powder and 100-200 ㎏ environmental protection disinfectant into the aquaculture pond regularly, which can effectively isolate the pollution source at the bottom of the pond from the water body, form a thin isolation film at the bottom of the pond, and control the concentration of a large number of toxic substances. It can also kill pathogens in water and has certain cleaning and anti-inflammatory effects on sea cucumbers. However, when adding quicklime powder, we must pay attention to the dosage and uniform spraying to minimize direct contact with sea cucumber. Once it is not well controlled, it is easy to cause harm to the sea cucumber.

Tip 3: Add 1% antibiotic, 0.00 1% vitamin VC, 1.5% allicin or 1.5% Sanhuang powder to the feed to ensure the normal development and healthy growth of sea cucumber. According to the fact that the rotten skin syndrome of sea cucumber mostly occurs in winter and spring at low temperature without feeding, the sick sea cucumber often has the characteristics of excretory reaction. After excretion, the sea cucumber loses its feeding ability and the chance of cure. Therefore, feeding medicinal feed as early as possible before winter, adding antibiotics and Chinese herbal medicines to the mixed feed can increase the antibacterial effect of sea cucumber, adding VC can promote the normal growth of sea cucumber, avoid the occurrence of diseases, and have a certain detoxification effect, thus enhancing the disease resistance of sea cucumber in winter and achieving the purpose of preventing winter diseases in autumn.

Tip 4: regularly use mechanical water lifting or set up an aerator to improve the dissolved oxygen in the pool water. Usually, when there is no wind in the aquaculture pond, the phenomenon of dissolved oxygen stratification in the water layer is serious, especially when winter goes to spring, the temperature gradually exceeds the water temperature, and the surface water temperature is higher than the bottom water temperature, which makes the water temperature stratified, and the bottom water layer of the pond is often in an anoxic state. When using machinery or opening the aerator, it will cause the vertical flow of the water layer. Lift water or turn on the aerator 2-3 times a day, and the aeration and internal circulation time should reach 2-3 hours each time, which will have a very good effect on aeration and disease prevention.

Tip 5: Put biological agents and beneficial bacteria regularly, and put 3-5 ㎏ photosynthetic bacteria, beneficial bacteria and other agents per mu, which can not only decompose organic substances such as feces, residual bait and dead algae in pond water, but also reduce the ammonia nitrogen content in pond, make the aquaculture water clean, improve the water quality and sediment environment, increase the immunity and disease resistance of sea cucumber, prevent and reduce the occurrence and spread of bacterial and viral diseases, and inhibit harmful algae.