【Cause】Edwardian bacteria
【Symptoms】】
1, External symptoms
At the beginning of the disease, the diseased fish have a decreased appetite and swim alone, but there are no obvious symptoms on the outside. As the disease progresses, congestion spots appear on the top of the head of the sick fish, and continue to expand, and finally a suspected "saddle" shaped lesion is formed in the skull between the eyes, and in severe cases, the top of the head is perforated, the skull is cracked, and even the brain tissue is exposed. Therefore, farmers are often called "violent head disease", "split head disease", "red head disease" and so on. Before dying, the sick fish loses its balance, hangs in the water, in the shape of "hanging water", and when stimulated, it is a spiral-like rapid flip or irregular swimming, and then death occurs.
2, Internal symptoms
Anatomically diseased fish, common muscle congestion, a large amount of yellowish ascites in the abdominal cavity, no food in the stomach and intestines, intestinal congestion, inflammation, gastric cavity is filled with gas and light yellow watery liquid. Hepatomegaly has large bleeding spots, or the liver is earthy yellow, the spleen is necrotic, there are moldy black spots on the kidneys, and the gills are pale and blood loss.
【Popularity】】
1. Hazard objects
The disease occurs throughout the culture of yellowtails, but is the most harmful to fry rearing and adult culture, and sometimes some diseased fish can be seen spinning in the water body and die soon after. Especially in the fry rearing process, the mortality rate can be as high as 80-90%. In adult culture, the disease is mostly sporadic, and in a few cases there are acute outbreaks.
2. Epidemic season
The epidemic of this disease has obvious seasonality, may to October is its epidemic season, June to August is its peak epidemic period, the epidemic water temperature is 20-30 °C, and the onset is more serious at 25-28 °C. In the high temperature season, the disease spreads quickly, and when the water temperature is 25-30 ° C, a large number of sick fish will die.
【Prevention and control measures】
Due to the serious harm of Edward's disease in yellow jaw fish, the concept of healthy breeding and rational use of drugs should be implemented in aquaculture production to carry out comprehensive prevention and control.
1. Select robust seedlings
Many of the pathogens of yellow jawed fish storm head disease come from broodstock and nursery water sources, so before selecting seedlings, we must fully understand the technical strength of the nursery and the incidence of broodstock and seedlings, select high-quality seedlings, and control the quality of good seedlings.
2. Maintain a good breeding environment
It is best to remove excess silt from the bottom of the pond before stocking fingerlings, then thoroughly disinfect each mu with 100 kg of quicklime, and then inject unpolluted rivers into the sun.
Generally in the middle and late stages of aquaculture, due to the accumulation of wastes such as excreta and residual bait, a certain degree of water quality deterioration and substrate deterioration, ammonia nitrogen and nitrite also have a certain accumulation, and yellow jawfish belong to benthic fish, very susceptible to the deterioration of water quality and substrate impact, so it is necessary to strengthen the monitoring of water quality and substrate, regular regulation and improvement.
3. Strengthen breeding management
3.1 Turn off the feed
Choose a nutritious, high-quality compound feed for feeding.
The daily feeding amount is 80% full as the standard, try to leave no residual bait, and if necessary, the amount of feeding can be reduced or even stopped, so as to avoid too much residual bait causing water pollution. At the same time, according to the growth of yellow jaw fish and changes in the weather, timely adjust the nutritional level of feed and its feeding amount, do a good job of "five certainties (quality, rationing, timing, positioning, and fixing people)" feeding work, to ensure that yellow jaw fish can eat well every day, remember not to pour the feed into the feeding bucket before feeding.
3.2 Regular health care
In the case of intensive farming, the disease resistance of yellow jaw fish is highly susceptible to various adverse factors and decreased, so it is necessary to regularly take functional additives to improve resistance and promote growth.
3.3 Insist on conducting three pond patrols per day
Carefully observe the eating and other activities of the yellow jaw fish, find problems in time, and deal with them in time. At the same time, do a good job in the cleaning and sanitation of the pond, clean up the residue in the pond in time, fish out the sick and dead fish in time, reduce the spread of pathogenic bacteria, and create a good environment for the healthy growth of yellow jaw fish.
4. Drug prevention and treatment
4.1 Prevention
In the whole process of breeding, attention should be paid to the regular disinfection of the aquaculture water body and the regular feeding of medicinal feed to reduce the number of pathogenic bacteria in the water body and enhance the disease resistance of the yellow jaw fish. Water disinfection drugs should be selected with efficient mild disinfectants, such as compound iodine solution, mu fungus elimination (20% glutaraldehyde solution) and so on. The drugs added to the drug feed should be mainly Chinese herbal medicines and vitamins, and try to avoid the addition of antibiotics and chemical synthetic antibacterial drugs, so as not to cause drug harm and increase the difficulty of subsequent treatment.
4.2 Treatment
(1) Treatment when there is a parasitic infection
Step 1: Stop eating and kill insects.
For seedlings under 5 cm: 1 pack of gramsporine (trade name) + 1 pack of sanhuangshan (500g) (trade name) per mu of rice soaked in boiling water for 3-5 hours after the whole pond is sprinkled, once a day, 2 times a row.
For seedlings above 5 cm: 1 bottle of whole pond per 2 acres of rice with wheel net (trade name), once a day, and used 2 times.
Step 2: Take antibacterial drugs internally.
The disease is mainly an infection of the nervous system, so it is necessary to choose drugs that easily cross the blood-brain barrier for internal administration, and the course of medication must be extended.
Scheme 1: Per kilogram of fish per day with 0.2-0.4 g of Dakella (Enrofloxacin powder) + 0.15 g of stress ninsII. type, made into a drug bait feeding, continuous use of 7-10 days for a course of treatment, in severe cases, stop the drug for 2 days, and then separately feed stress nin III type bait for a course of treatment.
Scheme 2: Per kilogram of fish per day with 0.1-0.2 g of Betakella + 0.15 g of stress ninnin type III., made into a drug bait feeding, continuous use of 7-10 days for a course of treatment, when the disease is severe, stop the drug for 2 days, and then separately feed a course of stress nin iii. type bait.
(2) Treatment without parasitic infection and mass death.
Topical drugs and methods of use: the compound iodine solution is sprinkled in the whole tank, so that the concentration in the water body reaches 0.1-0.3ml/m3, that is, 66.7-200ml per 667m3; or the whole pool of the mu bacteria consumption solution is sprinkled throughout the pool, so that the concentration in the water body reaches 0.2g/m3, that is, 133g per 667m3;
Internal medication and method of use are the same as parasitic infections.
(3) Treatment without parasitic infection and sporadic death.
Topical drugs and methods of use: clean water spirit whole pool throwing, so that the concentration in the water body reaches 0.25-0.4g/m3, that is, 166.7-250g per 667m3 drug use; or the use of Lebijing whole pool sprinkling, so that the concentration in the water body reaches 0.25-0.4g/m3, that is, 1000g per 667m3 drug;
Medications taken internally and how to use them:
Each kilogram of fish is fed with 0.25 g of sanhuangshan + 0.15 g of stress nin type III + 0.1 g of aquatic compound multi-dimensional per day, made into medicinal bait, and used for 7-10 days for a course of treatment.
Or per kilogram of fish per day with 0.1 g of plate yellow powder + 0.15 g of stress nin III. + 0.1 g of aquatic compound multi-dimensional, made into medicinal bait feeding, for 7-10 days for a course of treatment.
4.3 Precautions
(1) If the condition is serious, it is necessary to choose the iodine preparation and glutaraldehyde preparation with less irritation to the fish body for disinfection.
(2) Within 1-3 days of starting treatment, there may be a further increase in death, which is normal.
(3) Pond fish basically stop dying, you must sample 2-4 fish, dissect, check liver, gallbladder, kidney symptoms, if alleviated, you can continue to feed Sanhuangshan, Plate Huangshan and other Chinese herbal medicines for consolidation treatment.
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