Prevention and treatment of bacterial septicemia fish disease

1. Pathogens, symptoms and harmful objects of bacterial septicemia. The disease is mainly caused by a variety of bacteria, such as Aeromonas hydrophila, Yersinia Luke and so on. The main symptoms are that in the early stage of the disease, the mouth, head, chest and abdomen, orbit, operculum epidermis and fin base of the diseased fish are congested, Gill filament ulcer, hyperemia, and in severe cases Gill filament rot. Open abdominal cavity has yellow or red ascites, liver, spleen, kidney, gallbladder swelling, some fish anal redness and fluid overflow, sick fish systemic lesions, slow movement or bouts of wild swimming in the water. The main harmful objects are all kinds of crucian carp, blunt snout bream, carp, silver carp and bighead carp, rice field eel, mandarin fish, carp and so on.

Second, the main causes of bacterial septicemia. First, the deterioration of water quality, excessive silt at the bottom of the pond, excessive feeding and fertilization, deterioration of water quality and sediment in fish ponds, low transparency of water and low dissolved oxygen, make farmed fish live in a harsh environment for a long time, leading to the disorder of fish immune system and pathogens. Second, the nutritional imbalance of fish, in high-density culture conditions, long-term feeding of a single species of food, so that too much or too little of a substance will cause fish-related functional disorders, directly affect the growth, development and disease of fish. Third, the variety degenerated and the disease resistance decreased due to long-term inbreeding. Fourth, improper prevention, not doing a good job in disinfecting fish ponds, fish species, food farms, tools and water bodies, feeding bait not in accordance with the "four fixed" scientific feeding methods, and now all kinds of water bodies are raising fish, and fish farmers lack knowledge of disease prevention, throwing sick and dead fish everywhere, causing fish to be passively infected and sick.

Third, preventive measures. First, do a good job in the detoxification of fish ponds and remove excessive silt from the bottom of the pond. 10 days before fish stocking, sprinkle every 667m2 surface (water depth 10cm) with 80~100kg quicklime throughout the pond. Second, long-term inbreeding is strictly prohibited to ensure the release of seedlings with strong and high resistance to disease. The third is to bathe the fish with 15~20g/m3 's KmnO4 solution or 30.5% salt water for about 20 minutes before entering the pond to kill the pathogens on the body surface of the fish. Fourth, the stocking density and collocation ratio should be determined according to the local conditions, the technical level of feeding and management and the ability of disease prevention, and the density should not be too high. Fifth, strengthen feeding and management, regularly sprinkle quicklime and add new water, turn on aerator when possible, constantly improve water quality, adhere to the scientific feeding method of "four looks" and "four determinations", advocate less and more meals, feed natural and high-quality mixed feed as far as possible, do not feed deteriorating toxic feed, ensure that the fish are full and eat well, and improve their disease resistance. The sixth is to do a good job in disinfecting water, food and tools. In the main growing season of fish and the main epidemic season of fish disease, the aquaculture water body should be regularly sprinkled with chlorine-containing preparations such as strong chlorine, ClO2, king chlorine, water disinfectant, bromochlorohydantoin or bleach, and the acid water should be sprinkled with quicklime in the whole pool. The tools used in the sick fish pond must be disinfected, and the sick and dead fish should be fished out and buried in time, not littered everywhere. Seventh, before the epidemic of the disease, use an insecticidal drug to kill parasites, and pay attention to the instructions and scope of the use of insecticidal drugs, in order to prevent the poisoning and death of special aquatic products such as shrimp and crab, mandarin fish and clam in the pond. Eighth, in the epidemic season of the disease, oral drugs such as Yuxuening, Yukangda or furazolidone are added to the feed for 5 days at a time, once a month, if the fish in the surrounding pond has developed the disease, chlorine preparations should be sprinkled.

Fourth, the treatment method. The disease is pathological changes all over the body, so the treatment must be combined with internal administration and topical application.

Oral administration of Yukangda, Yuxuening and so on, the dosage is 20g per kg feed, continuous feeding for 5 days for 6 days as a course of treatment. Pay attention to the medicine and feed should be fully mixed, each feeding amount to ensure that the fish finish in about 1 hour.

The method of external use is as follows: on the first day, insecticides such as 0.5g/m3 's crystal trichlorfon or 0.7g/m3 's CuSO4 can be used to kill fish parasites, and on the second and third days, continuous spraying of 0.5g/m3 's strong chlorine or 0.3g/m3 's king of chlorine, ClO2, water disinfectant Ling or 0.15g/m3 's bromochlorohydantoin or 1.2~1.5g/m3 's "90" disinfectant. The main method to treat the disease in our city in the past three years is to sprinkle it in the whole pool with "fishing high-efficiency double-effect spirit" plus CuSO4 on the first day, and the dosage of fish-use double-effect spirit is: 1ml/30m3 water body, 100ml CuSO4 per 3000m3 for 0.5g/m3, and then sprinkle with chlorine-containing preparation in the whole pool on the second day, the therapeutic effect is very ideal. In addition, our city aquatic products improved seed farm tried crystal trichlorfon, CuSO4, FeSO4 three kinds of drugs mixed and dissolve after the whole pool sprinkled, the dosage ratio is 0.6g/m3:0.6 g/m3:0.25g/m3, only one use of this method can be effective, this method saves labor, money, and the effect is good, but this method is not suitable for mixed culture of crab, shrimp, mandarin fish and other special aquatic products. In addition, after medication, we should pay attention to observe the weather, water quality changes and the activities of fish, once found that fish floating head should try to add oxygen or timely injection of new water. Attention should be paid to stopping medication in cloudy and rainy days, and sprinkling drugs in high temperature periods should be sprinkled after 3 p.m. in sunny days to prevent fish from dying in the pond.

It is best to sprinkle the whole pond with 30g/m3 quicklime one week after each spraying, so as to adjust the pH value of the water, improve the water quality and reduce the recurrence of fish disease.