(1) Symptoms:
White spot-like cysts appear on the body surface, fins, and gills of the affected fish. In severe cases, the entire body and fins are covered with white spots and coated with a white mucus layer.
(2) Prevention and Treatment Methods:
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Bathe the fish in a mercurous nitrate solution at a concentration of 2×10⁻⁶ mg/L. For water temperatures below 15°C, bathe for 2–2.5 hours; for temperatures above 15°C, bathe for 1.5–2 hours. After bathing, keep the fish in clean water for 1–2 hours to allow dead parasites and mucus to shed.
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Apply mercurous nitrate throughout the pond at a concentration of (0.1–0.2)×10⁻⁶ mg/L. Use 0.2×10⁻⁶ mg/L for water temperatures below 10°C, 0.15×10⁻⁶ mg/L for temperatures between 10–15°C, and 0.1×10⁻⁶ mg/L for temperatures above 15°C.
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Bathe the fish in a glacial acetic acid solution at a concentration of 167×10⁻⁶ mg/L. At water temperatures of 17–22°C, bathe for 15 minutes. Repeat the bath every 3 days, with 2–3 baths constituting one treatment course.
