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Erythroderma is also known as hemorrhagic rot disease, red skin plague, ruby plague and so on. Red skin disease is one of the main and common bacterial fish diseases of grass carp, bluefish, carp, tuantou bream, etc. Most of them are infected by Pseudomonas fluorescent, causing fish diseases in which the skin on both sides of the fish body is hyperemic and inflamed, and the scales are shed. It often occurs after transportation, net pulling operations or damage to the epidermis of fish in winter, so it can be commonly referred to as "fish injury disease". This disease mostly occurs in 2-3 years old large fish, which can also occur in fish that year, often at the same time as enteritis disease and rotten gill disease, forming complications, collectively known as "old three diseases".
1. Pathogens
The pathogen of erythroderma is Pseudomonas lucidum. Short rod-like, rounded at both ends, single or two connected, dynamic, extreme 1-3 flagella; spore-free, rod-shaped, gram-negative. Widely present in water, soil.
Colonies on the agar medium are gray, translucent, and begin to produce green or yellow-green pigments about 24 hours, diffuse medium; broth culture grows abundantly, uniformly turbid, slightly flocculent precipitation, and has a smooth and soft layered membrane on the surface, which is scattered with a shake. After 24 hours, pigments were produced on the surface of the medium; cup-shaped liquefaction after gelatin puncture for 24 hours, liquefaction in the upper layer after 72 hours, and pigmentation was present in the liquefied part; potato culture was moderately grown, slightly convex, smooth, and moist, with green colonies and green medium for 2 days. Rabbit blood agar β hemolysis.
Second, the cause of the disease
The source of infection is water bodies, tools and carrier fish contaminated with Pseudomonas fluorescent. When the surface of the fish is intact, pathogens cannot invade the skin of the fish. Only when the fish is mechanically damaged by fishing, transportation and stocking, or frostbite, or the body surface is parasitized by parasites and damaged, the pathogenic bacteria Pseudomonas fluorescent can take advantage of the deficiency and cause the onset of the disease.
Sick fish mostly occur in the process of pulling nets, transferring ponds, transporting, loading and unloading, etc., due to improper operation or barbaric fishing, causing damage to the body epidermis of fish, and most of them are complications.
3. Prevalence
In all fish farming areas in China, it is endemic all year round, especially after fishing, transportation, and after wintering in the north, it is most prone to outbreaks. However, it is more common in late spring, early summer and late autumn and early winter, and the peak of the epidemic is at the peak of water temperature of 25-30 °C, especially after fishing and transportation. The onset of the disease is often related to the injury of the fish body and is a conditional pathogen.
4, Symptoms
Sick fish with erythroderma are slow-moving, unresponsive, weak, solitary, and weakly swimming between the surfaces of the water. Bleeding on the surface of the body is inflamed, and the scales are shed, especially on the sides of the fish body and on the abdomen. Sometimes the body surface is rough, the thick nails fall off the nails, and the debonding is not broken. Low temperature period can often be secondary to water mold infection at the surface of the body, often referred to as "long hair", will aggravate the disease, the onset of the disease will die within a few days.
The color of the head of the diseased fish is significantly darker, the base of the fin or the entire fin is congested, the end of the fin is decayed, often rotting away for a while, and the soft tissue between the fins is often destroyed, making the fins broom-shaped, called "borer fins".
Sometimes the upper and lower jaws and gill caps of fish are also engorged and inflamed, showing lumpy erythema. Even in the upper and lower jaws of fish and the gill cap part of the congestion, the skin on the inner surface of the gill cover is often corroded into a round or irregular transparent window, commonly known as "open skylight", which is complicated by gill rot disease.
When the sick fish suffering from red skin disease stop eating and refuse to eat due to the disease, the intestine is inedible, and sometimes the intestines of the fish are also congested and inflamed, and the intestinal lumen is full of mucus, which may also be secondary to enteritis.
5. Diagnosis and basis
Initial diagnosis based on symptoms and prevalence. To confirm the diagnosis, the pathogen needs to be isolated and identified. The pathogen of this disease cannot invade the skin of healthy fish, so the sick fish have a history of injury, which is important for diagnosis.
Because the symptoms of erythroderma are more obvious and are on the body surface, it can be diagnosed according to the appearance symptoms and pathological changes, so the symptoms of erythroderma can usually be diagnosed by naked eye observation. Carefully observe the lesion site on the surface of the body: whether there are scales shedding, whether there are bleeding spots or bleeding spots at the scale shedding; whether the fins are intact and whether the base is congested; further observe whether the muscles have bleeding spots and whether the intestines are red.
Sixth, the difference between red skin disease and scabies disease
Note that the red skin disease is similar and different from the furuncle disease, the surface of the fish body in the early stage of the furuncle disease is also inflamed and hyperemic, the scales fall off, but it is limited to a small range, and the red and swollen part is higher than the body surface, that is, the "sore" of the furuncle disease grows on the surface of the body.
Prevention
(1) In the process of fishing, transportation, stocking and other operations, try to avoid injuries to the fish body. When buying fish and re-raising, try to find a fish farm with skillful operation and good reputation. Don't buy long-distance fish, don't market fish, don't buy big fish (big fish toss and struggle), don't be weak fish.
(2) Select high-quality robust seedlings, disinfect the seedlings once before planting the pond or turning the pond, or soak the seedlings in the pond or the pond. For example, 1-3% of salt water, each cubic meter of water body put 15-20 grams of potassium permanganate aqueous solution medicinal bath for 15-30 minutes, or soaked in another bactericidal bath.
(3) Strengthen feeding management, maintain excellent water quality, and strictly prevent fish body injuries; in the northern wintering pond, the water level should be deepened to prevent frostbite of the fish body; feeding high-quality feed to enhance the resistance of the fish body.
(4) When it is found that the fish has parasite parasites, the parasites should be killed and expelled in time (internal insects).
(5) Timely disinfection with drugs after transportation, net pulling and other operations. After the fish body is found to be injured, the disinfectant should be sprinkled 1-2 times throughout the whole pool immediately. If there are signs of onset, treat them immediately.
(6) Dissolved oxygen is sufficient. It is advisable to maintain the dissolved oxygen content in water at about 5 mg/L.
(7) Hanging basket (bag). In the bait table area, use medicines such as copper sulfate or bleach powder to hang baskets and hanging bags.
8. Treatment
Red skin disease, like other fish diseases, should be prevented and treated early. In normal times, preventive medication can generally be used once a month, and after the fish are transferred to the pond and the pond is lowered, regardless of whether there is injury or not, it is beneficial to prospective medication prevention and control. In the early stages of the disease, it is still treatable, and it is a course of treatment for 3-5 days. If the condition is severe, it is difficult to have a therapeutic effect. The following are the options for medication and are recommendations only.
1. External medicine: disinfectant fungicide and insecticide mainly.
(1) It is recommended to refer to the prevention and control methods of fish sepsis and hemorrhagic diseases. The whole pool is sprinkled with violent hemocytopen (or violent hemocytic stop) and mixed killing of Terane (or mixed killing), each drug is used twice (day) for one (4 days) course, dosage and precautions according to the instructions for use. The use of hemostatic factor of tyrannical hemostasis and mixed killing of Tyran's insect bacteria double killing, the effect of this method is remarkable.
(2) The whole pool is sprinkled with disinfectant and fungicide.
8% bromochlorohydantoin, 0.2-0.3 g/m3.
Chlorine dioxide 150-200 g/mu, severe use up to 250 g/mu.
Povidone iodine 250 ml/acre.
Fish ponds with poor bottom quality are sprinkled with strong chlorine (2 kg/5 mu) + glutaraldehyde (125 ml/mu).
Ponds with good substrate can be sprinkled outside glutaraldehyde (125 ml/mu).
Sodium dichloroisocyanurate (contains 60% effective chlorine) 0.5-0.6 g/m3.
Trichloroisocyanuric acid (contains 85% effective chlorine) 0.4-0.5 g/m3.
45% benzalkonium bromide 100 ml + 20% glutaraldehyde 250 ml is used together.
(3) Use insecticides. For example: enemy insects, copper sulfate and other series of insecticides spilled.
(4) Chinese medicine for external use.
gallnut. Put 2-4 grams per cubic meter of water. First grind the five-fold seed and soak it in boiling water.
Black oak leaf. Put 3.7 grams of dried black oak leaves per cubic meter of water (8 kg of fresh eucalyptus leaves are equivalent to 2 kg of dried eucalyptus leaves). The leaves are soaked in 20 times the weight of 2% lime water overnight, then boiled for another 10 minutes to improve efficiency, and then sprinkled all over the pool with water and slag.
rheum. Rhubarb is said to be effective in the prevention and treatment of fish erythroderma, viral haemorrhagic disease, bacterial gill rot, enteritis disease, and the cost of medication is low.
a. Rhubarb 2.5-4.0 grams per cubic meter of water. First soak the rhubarb in 20 times the weight of 0.3% ammonia water (which can be purchased in the chemical reagent store) to improve the efficiency, and then sprinkle the whole pool evenly with the water slag.
If it is inconvenient to purchase ammonia, it is mixed according to the ratio of 1 kg of rhubarb plus 20 kg of ammonium bicarbonate, and the whole pool is sprinkled after soaking in water for 12 hours, so that the concentration of the pool water liquid is 3ppm (g / cubic meter), which is said to be effective in the treatment of erythroderma and bacterial gill disease.
b. Sprinkle the whole pond with rhubarb and copper sulfate (0.5 g/m3 each), which has a good preventive and therapeutic effect on the "four diseases" of grass carp.
2. Internal medicine: mainly antipyretic and detoxification agents. Internal medication is only effective if the condition is mild or the fish is still being fed, and it is useless or ineffective when the disease is serious or refuses to eat.
(1) Take antibiotics internally. For example: florfenicol, sulfa-mmethoxypyrimidine, co-trimethamine, thiamphenicol, norfloxacin or ofloxacin or flumethoquine, dosage and precautions according to the instructions for use.
(2) Internal use of Chinese herbal medicine. For example: plate yellow powder, five yellow liquid, astragalus immune polysaccharides and so on.
Three yellow scatters. Rhubarb, yellow cedar, skullcap (commonly known as "three yellows") three kinds of Chinese medicine powder according to the ratio of 5:3:2 combination, every 100 kg of fish with "three yellow powder" 2 kg, salt 0.6-0.8 kg, mixed into 20 kg of concentrate, add an appropriate amount of water, made into a ball or granular bait fed in the dining field, continuous feeding for 3 to 6 days. Or: every 200 kg of eating fish with rhubarb 250 g, 150 g of yellow cedar, 100 g of skullcap, crushed and add 2 kg of salt, water and evenly mixed with flour to stick to the young leaf grass, dried and fed grass carp, you can also mix in the feed to feed feeding feeding fish, continuous feeding for 5-7 days.
A combination of Chinese and Western medicines. On the first day, according to the weight of each 100 kg of fish, use compound cinotromine 8 grams, berberine hydrochloride 4 grams, rhubarb soda slices 8 grams, andrographis 8 grams, mixed and mashed, mixed into the flour after cooking and lifting, thoroughly stirred, mixed with 40 kg of tender grass, dried and fed, 4 days for a course of treatment, the 2nd-4 days of the dosage halved.
Rhubarb garlic. Mainly bleeding disease, rotten gills, enteritis, red skin disease concurrent, per 10,000 fish with crushed rhubarb, mashed fresh garlic, salt 1 catty each, mixed with an appropriate amount of refined feed to make medicinal bait to feed the fish, once a day, continuous feeding for 3-5 days.
3. Other measures:
(1) Streptomycin sulfate. When breeding broodstock or precious fish suffer from severe red skin disease, or have stopped eating, intramuscular injection of streptomycin sulfate, 20 mg per 2 kg of fish body weight, generally 1 injection can be cured, if it has not been cured within 3 days, it can be injected again.
(2) Soak in herbs. For example, 30 catties of fresh or young leaves of castor beans per acre, tied into bundles, placed in fish ponds soaked in liquid.
(3) Transfer water to change the bottom. During the onset of the disease, attention is paid to the bottom improvement and regulation of water quality.
(4) Dissolved oxygen is sufficient. Fish disease and treatment need to have enough dissolved oxygen in the water, and the addition of an aerator is very beneficial to the treatment effect and fish body recovery.
4. Commercially available fish medicines for external and internal use for the treatment of erythroderma.
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