Key Points and Detailed Methods for Black Carp Disease Prevention and Treatment
Black carp is an important fishery resource in the middle and lower reaches of the Yangtze River and lakes along the river, and a major culture species in lakes and ponds. It is one of the "Four Major Chinese Carps" in freshwater aquaculture in China. Juvenile black carp are prone to hemorrhagic disease, 2-year-old fish frequently develop enteritis, and sporozoosis and bacterial gill rot are also very common. Let us take a look at black carp disease prevention and treatment techniques together!
Black Carp Hemorrhagic Disease
[Symptoms]Caused by an unnamed virus. Similar to grass carp hemorrhagic disease, with no obvious congestion on the body surface; the main manifestations are congestion of the intestines and muscles.
[Prevention and Treatment Methods]① During the disease season, for every cubic meter of pond water, sprinkle 0.6 g of dimethachlon or 0.7 g of copper sulfate over the whole pond, with 2 days as one treatment course. ② Inject inactivated vaccine into black carp fingerlings, using the same method as for grass carp fingerlings. ③ For every 10,000 fingerlings, use 0.25-0.5 kg of rhubarb or sweetgum leaves, grind into powder, decoct or soak in boiling water overnight, mix with bait and feed, for 5 consecutive days. Also mix Cleo-Yufukang with bait and feed, using 50 g of medicine per 100 kg of fish mixed with bait, once a day, for 3-5 consecutive days.
Sinergasilus Disease
[Symptoms]Sick fish have difficulty breathing, are restless and agitated, turn over or swim wildly at the water surface, with the upper lobe of the caudal fin often exposed above the water. Eventually they become emaciated and die of suffocation. Sick fish have abundant mucus on the gills, and the ends of gill filaments swell into club shapes, pale and bloodless.
[Prevention and Treatment Methods]① Use quicklime to clear the pond and kill worm eggs. ② Sprinkle 90% trichlorfon crystals over the whole pond at a dosage of 0.5 mg/L. ③ Sprinkle a mixture of copper sulfate and ferrous sulfate over the whole pond, with copper sulfate at 0.5 mg/L and ferrous sulfate at 0.2 mg/L.
Bacterial Enteritis
[Symptoms]Sick fish have a darkened body, reduced appetite or even refusal to eat, congested and inflamed intestinal walls with poor elasticity, large amounts of mucus in the intestines, and red and swollen anus.
[Prevention and Treatment Methods]Sprinkle chlorine dioxide over the whole pond at a dosage of 0.2 mg/L to 0.5 mg/L. Use allicin mixed with feed at 10-30 g/kg body weight, for 4-6 consecutive days.
Hepatobiliary Syndrome
[Symptoms]Sick fish have obviously enlarged livers that turn yellow and whitish, forming a "flower liver" or even partially or mostly becoming a "green liver." The body color darkens and becomes dull. Sick fish usually have a big belly and are obese, with loose scales that easily fall off, irregular swimming, poor appetite, and sluggish reactions.
[Prevention and Treatment Methods]Use high-quality compound feed, feed more live and fresh animal feed such as snails and clams, regularly use microbial preparations to regulate water quality, and when disease is detected, promptly spray hepatobiliary recovery agent and vitamin C onto the compound feed being fed.
Bacterial Septicemia
[Symptoms]Affected black carp have a strong feeding frenzy 1-2 days before death, while floating on the water surface, swimming slowly, and rising and sinking. Fish with severe disease are anorexic or refuse to eat, remain motionless or have paroxysmal wild swimming, some rub against the pond edge, and finally die of exhaustion.
[Preventive Measures]① Pond clearing and disinfection: In winter, drain the pond and remove silt, and thoroughly disinfect with quicklime or bleaching powder. ② Fingerling disinfection: Strictly prohibit long-term inbreeding, and ensure the stocking of healthy and disease-resistant fry. Before fingerlings are put into the pond, soak them in a 15-20 mg/L potassium permanganate solution or a 3-5% salt solution for about 20 minutes. ③ Drug prevention: From June to September, use a long-acting water disinfectant once a month. Every 30-45 days, feed 1 g of Yufuning per kg of fish body weight mixed with feed, for 2 consecutive days. During the disease epidemic season, every half month, sprinkle 0.2 g of chlorine dioxide per cubic meter of water diluted in water over the whole pond once.
[Treatment Methods]① On the first day of onset, use insecticide to kill external parasites on the fish. ② Sprinkle 0.3 g of chlorine dioxide per cubic meter of water diluted in water over the whole pond, and apply again after an interval of 1 day. ③ Feed pelleted feed made with 0.05 g of compound sulfamethoxazole per kg of fish body weight, twice a day, for 5 consecutive days.
Sporozoosis
[Symptoms]There are white round cysts on the body surface and skin of the fish. Internal organs, whether adipose tissue or other organs, also have white cysts, and the gonads have even more obvious white spots, making them easy to distinguish from the ovaries.
[Prevention and Treatment Methods]① Thoroughly clear and disinfect the pond with quicklime. ② For every 50 kg of fish, feed 75 g of sulfur powder mixed with bait, once a day, for 4 consecutive days. ③ Sprinkle 0.15 mg/L of miechongjing over the whole pond. Or add 500 g of potassium permanganate per cubic meter of water, fully dissolve, and soak sick fish for 30 minutes. ④ Dissolve 40 kg of quicklime in water and sprinkle over the whole pond to adjust the pond water pH to about 8, then on the third day and fifth day, dissolve 30 kg of quicklime in water each time and sprinkle over the whole pond once more.
Bacterial Gill Rot Disease
[Symptoms]Sick fish have increased mucus on the gills and swollen gill filaments. In severe cases, the ends of gill filaments are damaged and cartilage is exposed. The inner surface skin of the operculum is congested and inflamed, and the middle part erodes into a round or irregular transparent small window, commonly known as "open skylight." The color at the edges of the fins often fades.
[Prevention and Treatment Methods]Sprinkle 0.4 mg/L to 0.5 mg/L trichloroisocyanuric acid, or 0.2 mg/L to 0.5 mg/L chlorine dioxide, or 0.2 mg/L to 0.3 mg/L dibromohydantoin over the whole pond. Mix sulfadiazine into the feed and feed at a dosage of mg/kg body weight, for 5 consecutive days, with the first dose doubled. Orally administer aquatic compound vitamins and vitamin C for one week.