Three Major Disease Prevention and Treatment Methods for Pond Fish in Spring and Summer

1 Carp Hemorrhagic Disease

1.1 Symptoms and Causes

The scales on the abdomen of the diseased fish, the fin rays and the caudal peduncle become congested and red. The diseased fish float up close to the ice layer or float on the water surface, gather in groups and swim slowly near the pond edge, and gradually die.

① Hemorrhagic septicemia. The diseased fish appear normal on the outside, or the area under the abdominal scales is congested and red. When the diseased fish is dissected, blood-tinged fluid emerges from the body cavity, and the internal organs have petechial hemorrhages. The disease is caused by Aeromonas hydrophila.

② Brown blood disease (hemorrhagic gill disease). The gill filaments of the diseased fish swell and become dark in color, and some gill filaments form aneurysms. When the condition is severe, the blood is coffee-colored, and gasping at the surface occurs even when dissolved oxygen in the pond water is sufficient. The disease is caused by excessive levels of ammonia, nitrogen and nitrite in the pond water.

③ Recessive hemorrhagic disease. When first taken out of the water, the diseased fish have normal body color and relatively little mucus on the body surface; after being held in a cage for 2 to 3 hours, congestion appears on the body surface. A small number of the fish have a red upper jaw (red lips); after 7 hours of holding, the diseased fish begin to die one after another. On dissection, the liver of the diseased fish shows fatty liver or mottled liver, and the gallbladder is enlarged or only the gallbladder is present (also called no gallbladder). The disease is caused by long-term blind feeding of high-protein feed, combined with low protein utilization efficiency.

④ Dominant hemorrhagic disease. The area under the abdominal scales, the caudal peduncle and the gill cover of the diseased fish are congested, and the caudal fin and dorsal fin are blood-red. On dissection, muscle congestion is visible, the liver is enlarged and pale, and the gallbladder is enlarged and light in color. The cause is the same as that of recessive hemorrhagic disease.

1.2 Prevention and Treatment Methods

Carp hemorrhagic disease is relatively difficult to cure in spring, and the course of the disease is long. It is generally detected and treated in summer and autumn.

① Improve the water environment. Divide the pond early or change the water, and regularly splash quicklime solution or broadcast zeolite powder dry.

② Salt bath. Five minutes before each feeding, dissolve 3 to 4 kg of salt in water and splash it around the feeding platform, 1 to 2 times per day. The effect is even better if it is done at the same time as feeding medicated bait.

③ Disinfect the fingerlings. When stocking fingerlings, if there are no other diseases, it is best to bathe them for 5 to 10 minutes in an aqueous solution of 5% salt and baking soda (the ratio of the two is 3:2).

④ Strengthen feed feeding to promote recovery of physical strength. Before overwintering, add trace elements or drugs such as vitamin E, vitamin C, vitamin B1, vitamin B3, vitamin B6, vitamin B12, choline and septicemia powder to the feed being fed, and add little or no mineral additives to the feed.

2 Scale Protrusion Disease

2.1 Symptoms and Causes

The scales of the diseased fish open outward, and the shape of the fish body is like a pine cone. The base of the scales is edematous, and with slight squeezing, accumulated fluid or blood-tinged accumulated fluid spurts out. The disease often occurs together with ascites disease. The diseased fish have protruding eyeballs, and sometimes bleeding is accompanied at the base of the fin rays and on the skin surface. The abdomen is distended, and there is a large amount of accumulated fluid in the abdominal cavity. The diseased fish swim slowly, have difficulty breathing, turn their bodies upside down with the abdomen facing up, and die after 2 to 3 days. The disease is caused by Pseudomonas punctata.

2.2 Prevention and Treatment Methods

① Improve the water environment. Divide the pond early or change the water, and regularly splash quicklime solution over the whole pond during the culture period.

② Disinfect the fingerlings. When stocking fingerlings, soak the diseased fish for 10 to 15 minutes in a mixed aqueous solution of 5% salt and baking soda (the ratio of the two is 2:3).

③ Disinfect the pond water. When the fingerlings develop the disease, splash bleaching powder solution over the whole pond twice (the drug concentration in the pond water is 1 ppm).

④ Feed medicated bait. Feed 5 g of antibiotics per 100 kg of fish per day for 5 to 7 consecutive days. The effect is better if combined with salt disinfection at the feeding site.

⑤ Handle gently and quickly. Handle gently and quickly when dividing ponds or transporting, and try to avoid injuring the fish body.

3 Protozoan Gill Rot Disease

3.1 Symptoms and Causes

After the ice melts in overwintering ponds in early spring, fingerlings often gather and swim scattered near the pond edge or in the downwind area, and the disease often causes explosive death of fingerlings. On sunny days, the diseased fish gather and float on the water surface, appearing to gasp from lack of oxygen. During training, they do not come to the feeding platform, or eat for a while and then scatter and gradually float to the surface, and their appetite is obviously reduced and growth is slow. When the gill cover of the diseased fish is lifted, tissue hyperplasia and increased mucus can be seen. The disease is caused by massive parasitism in the gills by protozoa such as Trichodina, Ichthyobodo, Chilodonella and Apiosoma.

3.2 Prevention and Treatment Methods

① Treat with the appropriate insecticide. When autumn fingerlings are merged into overwintering ponds or spring fingerlings are divided into ponds, soak the fingerlings in an aqueous solution of the corresponding insecticidal drug.

② Splash over the whole pond. Two to three days after disinfecting the pond water, splash chlorine preparations over the whole pond to prevent the lesions from secondary infection by other bacterial diseases.

③ Improve the water environment. Regulate the pond water quality by regularly splashing quicklime solution or broadcasting zeolite powder dry.

④ Oral administration of body surface insecticidal drugs. Regularly add insecticidal drugs to the feed to prevent the breeding of parasites on the body surface (including the gills).