Disease control of barracuda

Barracuda belongs to mullet-shaped spindle genus, the external shape is similar to mullet, but fat eyelids are not developed, living in coastal and estuarine, can also live in fresh water, is a wide-temperature, wide-salt fish. Under natural conditions, it feeds on diatoms and decaying organic matter, as well as benthos. Artificial bait can be used in pond culture. Among the farmed varieties, there is the saying of "south mullet and north shuttle". Barracuda culture is the main culture in Jiangsu and the north.

In recent years, the momentum of using freshwater ponds to culture barracuda in coastal areas has developed rapidly, from collocation culture to main culture. with the increase of stocking density, various diseases are also increasing, and even no harvest in some areas due to diseases. In view of the problems in the production process, we have tested and summarized, and now the diagnosis and control methods of common diseases in barracuda culture are introduced as follows:

Water mildew

Epidemic situation and symptoms: water mold mainly occurs in early spring and winter, and can grow and reproduce at water temperature of 5-26 ℃. All injured, frostbitten fish can be infected, diseased fish wound gray-white, cotton-like hyphae, diseased fish black, restless friction with solids in the pond, some diseased fish parasites appear vertical scales.

Prevention and treatment methods: ① should strengthen the feeding and management, improve the resistance of fish itself, and avoid scale shedding and frostbite. ② washed the injured fish with 400g / m3 of salt and 400g / m3 of baking soda solution. ③ was sprinkled with thiofloxacin in the whole pool. ④ was sprinkled with dimethazine in the whole pool. ⑤ internal administration of antibiotics to prevent bacterial infection, rapid control of the disease.

2. Rotifer disease

Epidemic situation and symptoms: it mainly occurs in the stage of fry and fingerling, which can be seen all the year round, but it is more common from May to August. After the disease, the body color of the fish is black, secretes a lot of mucus, and rotten gills appear, which can be diagnosed by microscopic examination.

Prevention and treatment methods: ① fish ponds are thoroughly cleaned with quicklime or bleach. ② mixture of copper sulfate and ferrous sulfate (5 ∶ 2), sprinkled in the whole pool at 0.7g / m3. ③ potassium permanganate 10g / cu m aqueous solution for 10min or 8m 10g / cu m cupric sulfate / cu ∶ 2 mixture bath. ④ neem branches and leaves are boiled with 20,30kg juice at a depth of 1 meter per mu and sprinkled. ⑤ raw leek is mashed with 3-5kg per mu and sprinkled with 100g salt in the whole pool. ⑥ oral fish worm nemesis per kilogram of feed plus 1 gram.

Third, finger ring disease

Epidemic situation and symptoms: the disease is mainly prevalent in late spring and early autumn, and the suitable temperature is 20-50 ℃. It is mainly parasitic on the body surface and Gill filaments of fish, and a small number of parasites have no obvious symptoms. The Gill filaments are swollen and a large amount of mucus is produced.

Control method: ① 0.3cm 0.7g / m3 crystal trichlorfon was sprinkled in the whole pool. ② Chenjing (albendazole) is used in accordance with the instructions. ⑧ mebendazole was taken orally 50 mg per kg of fish body weight once a day for 2 or 3 times.

Fourth, Gill rot disease

Epidemic situation and symptoms: the disease was prevalent from April to October, and the water temperature was above 20 ℃. Divided into bacterial Gill rot, parasites caused by rotten Gill. The diseased fish have black body color, slow response, loss of appetite, and swim alone in severe cases. There are green, gray, white or waxy spots on the Gill, and the Gill is mucous and often adheres to silt. In severe cases, the inner epidermis in the center of the operculum is congested and rotten into a circle, so it is said that "open skylight". Gill filament tissue microscopic examination showed that some parasites could be diagnosed as Gill rot disease caused by parasites, while no parasites were found in microscopic examination, but Radix columnar bacteria could be diagnosed as bacterial Gill rot.

Prevention and treatment: rotten gills caused by parasites must be killed first, and then treated. ① whole pool sprinkle bleach 1g / m3 or sodium dichloroisocyanurate, trichloroisocyanuric acid 0.3g / m3, once a day for 2 days. ② biquaternary amine salts such as BKC and other surfactants were treated for 3 times, once every other day, and the effect was particularly significant. ③ chlorine dioxide disinfectant, use according to product instructions. ④ reduces the use of dichloride and trichloride in high temperature season. Povidone iodine solution can be used once a day for 2 or 3 times.

5. Hemorrhagic disease

Epidemic situation and symptoms: it can occur mainly from April to November and when the water temperature is 9: 36 ℃, but in barracuda culture, it is mainly from June to September. This disease is easy to be confused with hepatobiliary syndrome. Early diseased fish have mild congestion symptoms in mouth, jaw, Gill cover, orbit, fin and both sides of fish body, a small amount of food in the intestine, hyperemia symptoms aggravate in severe cases, exophthalmos, abdominal swelling, ascites in abdominal cavity. Liver, spleen and kidney enlargement, intestinal congestion, gray Gill, purple Gill phenomenon, accompanied by swollen Gill, rotten Gill symptoms.

Prevention and treatment methods: use the prevention and treatment method of combination of internal and external use, general use for external use: ① trichloroisocyanuric acid 0.3g / cu m; continuous use for 3 days, once a day. ② binary chlorine dioxide 0.2g / m3 once every other day, 2 times in a row. Unitary chlorine dioxide and povidone iodine can be used alternately for 2 or 3 times in ③ high temperature season. General oral use: enrofloxacin 1g, Vc,2 g, hepatoprotective drugs 5g / kg of ① powder. ② added povidone iodine powder 5g / kg, Vc2~4 g / kg powder.

VI. Hepatobiliary syndrome

Prevalence and symptoms: Barracuda hepatobiliary syndrome mainly occurs in summer. Barracuda showed no obvious symptoms, but also similar to hemorrhagic disease, early diseased fish had no obvious symptoms, intestinal food was full, intestinal hyperemia, only purple Gill, white Gill phenomenon, pond sporadic death. With the arrival of high temperature in summer, the death rate increased, and the symptoms were obvious, such as purple Gill, body surface hyperemia, liver yellowish, purple, flower liver, gallbladder swelling black and dark green, but most of them had no ascites.

Prevention and treatment methods: before ① enters the high temperature season, water quality improver and bottom material improver should be used regularly. ② reduces the use of topical pesticides during the high temperature season. Reduce the use of chlorine preparation during the onset of ③, using biquaternary amine salt, povidone iodine, glutaraldehyde, etc., the dosage is the minimum dose of the product manual. ④ orally added enrofloxacin 1g, Vc,2~4 g, hepatoprotective drug 5g 10g, Sanhuang powder (as specified) per kilogram of powder.