What to do when yellow catfish (Pelteobagrus fulvidraco) contract "one red spot" disease? Detailed prevention and treatment methods

"One red spot" disease in yellow catfish is also called split-head disease, head swelling disease, etc. It is a common disease in yellow catfish farming in recent years. Fish from fry to adult fish can be affected, with fish between 1 and 3 liang being more commonly affected, especially two-year-old fish, which have a higher incidence. The disease occurs at water temperatures between 18 and 30°C, and is more severe at 25 to 28°C. Therefore, June to September each year is the peak period of incidence. The course of this disease is relatively long, and the cumulative mortality rate is relatively high. When the temperature drops, the disease may heal without treatment.

Causes and symptoms of "one red spot" disease in yellow catfish

1. Causes: When the pond water environment changes suddenly, such as algal crash, or when water quality deteriorates, such as decreased pH, increased ammonia nitrogen, elevated nitrite, low dissolved oxygen, and turbid water, the disease is also likely to occur. In addition, feed nutrition, scratches, feeding competition, and mechanical injury can all induce the disease. The disease is caused by chronic infection with "Edwardsiella". Its route of infection is through the nasal cavity, infecting olfactory cells, then entering the brain, and infecting the skull through the meninges.

2. Symptoms: The top of the head of affected fish becomes red, swollen, and ulcerated, until the skull is eaten hollow, forming a narrow, elongated cavity. In severe cases, there are also symptoms of reddening of the fins and a small amount of ascites in the internal organs. Diseased fish will slowly rotate at the water surface with the head up and tail down. Dissection shows pale yellow transparent fluid in the abdominal cavity, with hemolysis in some individuals; the liver is earthy yellow and lusterless, with bleeding points or bleeding spots; the spleen and kidney are swollen and congested; the stomach is enlarged, and the stomach wall is heavily congested, with water accumulation in the stomach in some individuals; the intestinal wall is red, and the intestinal mucosa sloughs off. Cutting open the intestine reveals yellow, thick, pus-like fluid.

Diagnostic methods for "one red spot" disease in yellow catfish

Generally, as long as the "one red spot" symptom is seen on the top of the fish's head, the disease can be judged. However, because diseased fish are weak, large numbers of Trichodina often parasitize the gills, so some people often misdiagnose it as trichodiniasis, but this parasitic infection is secondary.

Prevention and treatment methods for "one red spot" disease in yellow catfish

Infection with "one red spot" disease in yellow catfish spreads from inside the fish brain to outside the brain, so once the disease occurs, external disinfection and oral antibiotics are not very effective. Therefore, prevention is the key.

1. Emphasize controllability: Control the stocking density of yellow catfish at 2500 to 3000 fish, and choose suitable pond area and water depth. Generally, the area of a main culture pond is 3 to 5 mu or below 10 mu, and a water depth of 1.5 to 2 m is ideal.

2. Increase aeration: Yellow catfish have poorer tolerance to low-oxygen environments than other fish. Ponds with higher stocking density should be equipped with aerators to prevent fish from becoming oxygen-deficient and gasping at the surface. The average aerator power is 1.5 KW per mu.

3. Frequently improve the bottom: Regularly use bottom quality improvers to improve the substrate.

4. Skillfully stabilize water: Regularly use water quality improvers and microbial preparations to keep water quality stable.

5. Regular health care: Choose high-quality feed and regularly administer vitamins orally to increase the disease resistance and stress resistance of yellow catfish.

6. Proper insecticide and disinfection: Regularly use insecticides such as copper sulfate, etc., and regularly use disinfectants to eliminate hidden pathogens in the fish body and clear diseased organisms in the pond.