Control technology of vibrio disease in rainbow trout culture

The main results are as follows: 1. The symptoms of diseased fish are poor bait intake, black body color, hyperemia at the base of each fin, redness and bleeding on body surface, oral cavity and anus, anemia and whitening of Gill filament. Some have exophthalmos. The body surface of individual larger fish or adult fish often have erosion, rupture, whitening, dermis ulceration, muscle necrosis and other symptoms, and sometimes bleeding spots can be seen everywhere.

2. The pathogen is Vibrio anguillarum. Gram-negative, Brevibacterium, straight or slightly curved, round at both ends, single or 2 connected, no capsule, not acid-resistant, usually extremely simple flagellum, capable of movement. Hemolysis, fermented glucose produces acid and does not produce gas. It is sensitive to streptomycin, neomycin, oxytetracycline, chlortetracycline and vibrio inhibitor (0max 129) and produces toxins. The growth temperature is 5: 43 ℃, the suitable temperature is 18: 37 ℃, and the growth pH value is 5.8-10.5%. It can grow in 5% sodium chloride, but it grows poorly in sodium chloride-free medium, and does not grow in 6% sodium chloride. 3. Epidemic situation Vibrio rainbow trout vibrio disease is a worldwide epidemic disease. Rainbow trout from a few months after hatching to about 1 year old are prone to infection, rapid development of disease and high mortality. Larger rainbow trout and even parent fish can be infected, but most of them are chronic. The disease began to occur when the water temperature was above 18 ℃, and it was not until the water temperature dropped below 18 ℃ in autumn that it slowly stopped dying, resulting in serious losses. 4. Prevention and control methods (1) to vaccinate Vibrio anguillarum vaccine, generally use inactivated formalin vaccine. The vaccination methods are as follows:

Intraperitoneal injection: the effect is the best, and the immune effect is the fastest, and the dosage of vaccine is the least, but it is too troublesome and easy to hurt fish. After being anesthetized with ethyl methylaminobenzoate, inactivated vaccine 0.1 ml is injected into each fish. Immersion method: this method is more commonly used, 10000000 bacteria / ml immersion bath for 5 minutes, or 10000 bacteria / ml immersion bath for 3 hours; 0.94 g (wet weight) vaccine / liter and 5.32% sodium chloride hypertonic bath for 3 minutes. The immunization period was 113 days. Spray method: 7 kg pressure per 1 cubic centimeter, distance 15 cm, spray 5 minutes 10 seconds, containing 0.01 mg wet weight vaccine per gram carrier. Oral method: every kilogram of fish is fed with 4 grams of wet bacteria vaccine per day for 30 days. The disadvantage of this method is that the amount of vaccine is large and should be fed continuously for many times. (2) every 100 kg fish should be fed with 2-5 grams of doxycycline once a day. For six days in a row. (3) every 100 kg fish was fed with 5 grams of oxytetracycline bait once a day for 3 to 7 days. The above oral medication should be combined with the use of 0.3 mg / L strong chloride throughout the pool to disinfect the pond water and fish.