Prevention and Control Methods and Technical Key Points for Eel Summer Syndrome

Eel, pinyin: pinyin: mán Alias: white eel, white eel, river eel, Japanese eel, green eel, wind eel, Japanese eel. Eel refers to the general name of species under the order Anguilliformes. Also called eel, it is a fish that looks like a long snake and has the basic characteristics of fish. In addition, eels, similar to salmon, have migratory characteristics. Eels belong to fish, resemble snakes, but have no scales, and are generally produced in sea areas where saltwater and freshwater meet.

What are the symptoms of eel summer syndrome and how to prevent and control it?

Since the beginning of summer, eel ponds in various parts of Fujian Province have successively experienced comprehensive diseases such as eel slime shedding and septicemia, causing serious eel deaths. Based on some cases handled on site in southern Fujian, the following prevention and control methods are hereby proposed for reference by eel farmers.

The symptoms of eel summer syndrome are as follows: in the early stage of death, diseased eels have obvious symptoms of slime shedding or septicemia. Eels have weakened vitality, hang in large numbers on feeding tables or gather around drainage outlets, and do not feed. Among dead eels, there are not many symptoms of slime shedding, while symptoms of septicemia are more obvious. Because the number of cases with slime shedding or septicemia symptoms decreases in the later stage, red head or congestion and edema of the gills and lower jaw are more commonly seen, while other parts of the body surface are basically intact, and a few have abdominal cavities filled with blood; there are blood clots, faded liver, and whitened, swollen gill filaments, with a phenomenon of fading and whitening similar to that after being soaked in water. The number of deaths increases very quickly, and the mortality rate is relatively high. The entire disease cycle in one pond is 15 days to 20 days.

Effective treatment of eel summer syndrome:

Salt + traditional Chinese medicine + antibiotics. Keep the salinity at 4‰ to 7‰. The traditional Chinese medicines mainly include Coptis chinensis, rhubarb, Scutellaria baicalensis, Euphorbia humifusa, Artemisia capillaris, and Chinese gall. For antibiotics, doxycycline, oxytetracycline, norfloxacin, and flumequine can be selected. The medication period requires 1 to 2 courses of treatment, and severe cases may even require 3 to 4 courses.

Points to note for eel summer syndrome:

Treatment of pond water. Because medication may be needed for a long time, it is easy to cause deterioration of water quality. Therefore, after each medication cycle ends, it is best to carry out a large water exchange to keep the water environment clean.

During high-temperature periods, pay attention to changes in water temperature and water quality. Generally, ventilation should be strengthened to increase dissolved oxygen in the water, and when necessary, raise the water level for medication to prevent a sharp change in water temperature during medication from increasing eel deaths.

In the early stage of the disease, antibiotics also cannot obviously inhibit the progression of death. Conventional disinfectants such as bromochlorohydantoin, chlorine dioxide, Blue Angel + Virus Purifier can be selected to first control the development of the disease. If relatively large numbers of deaths occur, then use the methods described above.

After the peak death period has passed, the surviving eels in the pond must be made to feed as early as possible to restore their strength. Medicated bait can be fed to eliminate pathogens in the eels' bodies. At this time, disinfect the water body, and it is necessary to use drugs with low irritation. At the same time, Haizhongbao, multivitamins, glucose, etc. can be used for water baths for the eels to promote feeding.

While treating bacteria, attention should also be paid to checking whether there is branchiomycosis and parasitic disease. If so, they should be treated first, especially branchiomycosis, which must be killed first. Otherwise, when antibiotics are used, branchiomycosis may break out, causing large numbers of deaths. If the number of parasites is not large, treatment can be temporarily postponed.