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White mouth seed disease prevention and control technology
The white-blade seedlings are well-suited for high-density farming, but due to the high stocking density, they are highly susceptible to various diseases. If not managed promptly, these diseases can lead to significant losses. Common ailments include trichodiasis, bacterial infections, and cysticercosis. After three years of continuous research and on-the-ground experience, we have developed effective strategies for disease prevention and control in white-blade seedlings, which are summarized below.
Trichodiasis symptoms: In mild cases, infected Fish may show no visible signs. However, in severe infections, fry and fingerlings exhibit sluggish behavior, reduced feeding, and often swim near the surface, displaying a "race horse" pattern. Microscopic examination reveals swollen and congested gills, with dirt and mucus covering the body and gill arches.
Prevention and treatment: Depending on weather conditions and water clarity, when the weather is clear and the pond is rich in nutrients, apply 0.7–0.9 grams of copper sulfate per cubic meter of water. On cloudy days or when the water is thin, use 0.5 grams of copper sulfate ferrous sulfate solution per cubic meter. Perform microscopic checks in the evening. If no parasites are found, stop treatment. Otherwise, repeat the application of 0.2–0.4 grams of copper sulfate ferrous sulfate per cubic meter the next day for at least three times.
Intestinal symptoms: Infected fish tend to isolate themselves, move slowly, appear dark in color, and eat less. Early stages show an empty intestine with excess mucus, while later stages may display swollen anal regions, abdominal congestion, and pale yellow mucus in the intestines.
Prevention: Mix norfloxacin into the feed at a rate of 0.5% salt and feed for 3 days. For severe cases, extend the treatment to 7 days.
Bacterial disease symptoms: Affected fish become dark in color, swim sluggishly, lose appetite, and often float alone. Their fins and gills become inflamed, with increased mucus production. The gills swell and erode, and the intestines are empty with a layer of dirt on the surface.
Prevention: Add 0.3 grams of povidone iodine per cubic meter of water. Treat for 3 days, and simultaneously mix norfloxacin into the feed for 5–7 days.
Cysticercosis symptoms: In early stages, there are no obvious symptoms. When infestation is heavy, fish swim slowly near the shore, eat less, and show mucus buildup on the gills, swollen gills, anemia, and a large number of parasites under microscopic examination.
Prevention: Apply 0.4 grams of crystal trichlorfon per cubic meter of water after stopping medication. Monitor the fish closely, and if any abnormalities occur, turn on the aerator immediately. After 24 hours, replace one-third of the water.
Minamata disease symptoms: Blisters on the fish skin are common, and it's a serious issue for the industry as more than ten fry may be caught at night. Dead fish are rarely seen, but some may show red skin injuries or partial tail fin damage.
Prevention: Clear the pond with quicklime and treat the edges. If leeches are found, apply 0.3 grams of crystal trichlorfon per cubic meter of water around the pond’s edge, about 1 meter wide.
These methods have proven effective in reducing disease outbreaks and improving survival rates in white-blade seedling cultivation. Regular monitoring and timely intervention remain key to maintaining healthy fish populations.