Prevention and treatment of enteritis, gill rot and other complications in cultured grass carp

Symptoms of the diseased fish swimming slowly, loss of appetite; fish scales are basically intact; there are one or more boils on both sides of the dorsal fin, the hand touch is soft, there is a feeling of edema, the incision furuncle has pus-like fluid outflow; the anus is slightly red and swollen; Gill filaments are red and swollen, sticky dirt, the end of the rot, exposed cartilage, Gill cover inner epidermis hyperemia and inflammation, serious corrosion, showing a "skylight". Open fish body shows mesenteric hemorrhage, intestinal wall inflammation, serious cases are purplish red, there is basically no food in the intestine, with blood yellow sticky material; liver and spleen slightly swollen, liver yellowish, there are bleeding spots, crisp and fragile. Microscopic examination showed that there were a large number of rotifer parasites, occasional ring worms and intestinal pouch parasites in the hindgut. The mild mortality rate is 7%, and the severe mortality rate is about 30%.

According to the author's diagnosis, grass carp suffered from complications such as rotifer, Gill rot, furunculosis and enteritis.

Etiological analysis (1) the culture density is high, the water color is thick, and the water quality is not good. Some of the water quality is good, but it is thin. Some ponds do not have an independent intake and drainage system. (2) poor feed quality and unbalanced nutrition resulted in the decrease of fish body resistance and anti-stress ability. (3) the main green feed, Azolla, is mainly obtained from fields, ditches, ponds and red insect breeding fields, and is fed directly to fish without cleaning and disinfection. (4) the fertilizers applied by some farmers have not been fermented or fermented incompletely, resulting in the deterioration of water quality and the production of toxic gases, resulting in the deterioration of aquaculture water environment and the disease of fish species.

Prevention and control (1) improve water quality and increase the amount of water exchange. (2) compound feed and green feed (50% each), or cross-feeding of compound feed and green feed, or continuous feeding of compound feed for 4 days, stop eating for 1 day, and then continuously feed green feed for 2 days. The fed duckweed should be cleaned and fed in time after disinfection with 3% bleach solution or 10 mg / L potassium permanganate solution. Apply appropriate amount of fermented mature fertilizer or a small amount of chemical fertilizer. (3) stop feeding when you get sick. On the first day, every cubic meter of water was sprinkled with the mixture of copper sulfate and ferrous sulfate (5 ∶ 2). On the second day, it was sprinkled with 0.5g of chlorine dioxide per cubic meter of water. After 2 days of drug withdrawal, use again according to the above method. (4) while using drugs for external use, feed with oxytetracycline or sulfadiazine. Every 100 kg of fish weight was given 20 grams on the first day, and the dosage was halved from the second day to the sixth day. 6 days was a course of treatment. The patients with mild symptoms were basically cured in 1 course of treatment, and the seriously ill patients were basically cured in 2 courses.