Disease Control of pollution-free Culture of Monopterus Albus

With the development of aquaculture, more and more attention has been paid to the prevention and control of aquaculture animal diseases and pollution-free aquaculture. The development trend of disease control is from chemical drug control to biological agents and immune methods to improve the immune function of breeding objects, breeding disease-resistant varieties, ecological disease control and so on. make the product a green product.

Monopterus Albus is a freshwater economic fish with delicate meat, delicious taste, rich nutrition and medicinal health care function. it is a delicacy and nourishing health food loved by consumers at home and abroad, and it is very popular in domestic and foreign markets. Artificial cultivated ricefield eel is increasingly favored by producers because of its many advantages, such as small area, convenient management, low cost, remarkable economic benefits and so on. However, with the development of its intensification, there are more and more diseases of eel. Therefore, this paper introduces the disease prevention and control of ricefield eel combined with pollution-free culture, in order to provide reference for the majority of rice field eel farmers.

1 disease prevention

In order to carry out pollution-free culture of Monopterus Albus, we should first pay attention to its disease-resistant immunity or protect its inherent disease-resistance immunity. The main physical defense factors affecting the non-specific immunity of Monopterus Albus are scales, skin and other surface barriers, as well as the second line of defense composed of mucus and phagocytes. Scales, skin and mucus are important barriers for fish to resist pathogens and parasitic infections. Therefore, to protect fish from damage, to avoid enemy injury, pathogens can not invade, such as red skin disease, printing disease and water mildew disease will not occur. The high concentration of chemicals in culture water will promote Monopterus Albus to secrete a lot of mucus, but excessive mucus secretion can not protect the fish and can not resist the invasion of pathogens.

Monopterus Albus is difficult to detect from the population at the initial stage of the disease, so only by doing preventive work in advance can we avoid significant economic losses. Disease prevention must run through the whole breeding work. Here I mainly talk about the work in seedling selection and ecological disease prevention.

1.1 Seedling selection

Seedling selection is a key step in the whole breeding process. Attention should be paid to the following points in seedling selection of Monopterus Albus: ① infected Monopterus Albus, scars, blood spots on the body surface, redness and swelling of the Gill neck, etc., which are often caused by improper capture and temporary culture, and generally should be kept in cage for breeding. Eel species with abnormal state of ⑨ are not suitable for breeding. In the rice field eel tail purple, mucus lack or no mucus, this is a symptom of water mold infection; eel body has obvious red sunken spots, the size of soybeans, which is infected with skin rot; yellow eel head, thin neck, thin physique, serious curl-like, this is suffering from capillary nematode symptoms, very easy to spread. After long-term high-density collection, transportation and temporary cultivation of ③, Monopterus Albus often suffers from "fever" disease due to less water and more mucus, and the temperature rises. this kind of Monopterus Albus often dies one after another in the process of artificial culture and is difficult to cure. ④ poisoned by drugs, for example, poisoned by pesticides, the appearance is still difficult to identify, but often about 30 hours (depending on the temperature) after the body color turns gray, belly up, etc., not suitable for breeding. Ricefield eels driven by ⑤ in deeper water tend to have poorer physique and are more likely to die than those lying quietly underwater, so they are not suitable for breeding.

1.2 Ecological disease prevention

The prevention of eel disease should be based on ecological prevention. The main ecological prevention measures are that ① maintains a good space environment and the construction of the farm is reasonable to meet the requirements of the ecological habits of Monopterus Albus in dark, quiet and warm. ② strengthens the management of water quality and water temperature, keeps the water quality and bottom quality good, does not make the temperature difference of water exchange too large, and prevents the water temperature from being too high. ③ grows water plants or floating plants such as hyacinth and alternanthera philoxeroides in the farm and some climbing plants on the edge of the pond. ④ raised a small amount of Loach in the yellow eel pond to activate the water body, and several toads were put into each pond to prevent eel disease. ⑤ uses beneficial microbial preparations to improve water quality to maintain microbial balance and inhibit the reproduction of harmful microorganisms. ⑥ disease eel should be quarantined in time.

In addition, in the pollution-free culture of Monopterus Albus, in order to maintain the ecological balance in and out of the culture environment and objects, and to restrain or eliminate the invasion and infection of enemy organisms, in addition to using beneficial microbial preparations as far as possible to carry out biological control and creating a good ecological environment, it is also necessary to use disinfection and antimicrobials correctly and reasonably. However, attention must be paid to the variety, dosage and duration of the use of these drugs, such as never using banned drugs, not overusing them, and paying attention to the non-pollution requirements of prohibition period and withdrawal period, etc. If excessive use, not only can not achieve the purpose of disease control, but also will cause drug damage death, sometimes a large number of deaths occur in a short period of time, and sometimes continue to occur in the process of culture, the loss is quite serious.

2 disease treatment

2.1 Red skin disease

2.1.1 pathogen bacterial infection.

2.1.2 symptoms A disease caused by bacteria invading the skin of Monopterus Albus caused by injuries during fishing or transportation. The body surface of the diseased eel was locally bleeding, inflamed and the skin fell off, especially in the abdomen and both sides. Sometimes the upper jaw and operculum of Monopterus Albus are also congested and inflamed. Water mold infection is often secondary to the disease. The body of diseased eel is thin, and it is more popular in late spring and early summer.

2.1.3 Prevention and control methods ① should be operated carefully during fishing and transportation to avoid injury of eel; ② should be washed with 5~20mg/L bleaching powder for about half an hour before stocking; bleach basket should be used to prevent ③ during the onset season. The amount of bleach used is generally per 0.4g/L. ④ was sprinkled with 1.0~1.2mg/L bleach in the whole pool and 2~4mg/ L gallnut in the whole pool for 3 days, ⑤ was sprinkled with 0.05g alum per square meter, and then sprinkled with quicklime according to 25g/ cubic meter of water 2 days later.

2.2 Enteritis

2.2.1 pathogen bacterial infection.

2.2.2 symptoms of diseased eel swimming alone, swimming slowly, blackening of eel body, especially obvious head, erythema in abdomen and loss of appetite. Dissection of the intestine shows local congestion and inflammation, no food in the intestine and more mucus in the intestine. The disease is highly contagious, the course of disease is short, and the mortality is high. When the water temperature is 25-30%, it is the suitable epidemic temperature for the disease.

2.2.3 Prevention and control methods ① strengthen feeding and management, do not feed rotten and deteriorated feed, eliminate residual bait in time, and prevent the deterioration of water quality; during the onset season of ②, every 100g Monopterus Albus was fed with 30g garlic per day for 3 days for 5 consecutive days; ③ was mainly treated with the combination of internal administration and topical drugs. For external use, 1 × 10 × Emur6 × 2 × 10 × Emur6 bleaching powder or 10 × 10 × Emur6 concentration quicklime or 0.2 × 10 × Emur6 0.3 × 10 × Emur6 poultry erythromycin were sprayed all over the pond.

2.3 mosaic disease

2.3.1 pathogen bacterial infection.

2.3.2 A yellow round broad bean-sized plaque appeared on the back of the diseased eel and died in severe cases. The disease was prevalent again from June to August and reached its peak in mid-July.