(1) Symptoms:
In the early stages, small milky-white spots appear on the body surface or tail fins of the koi, covered with a thin layer of white mucus. As the disease progresses, the epidermis at the affected area thickens, forming large, paraffin-like growths. Affected fish become emaciated, swim sluggishly, show reduced appetite, remain at the bottom of the water, and may gradually die (see Figure 133).
(2) Preventive Measures:
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Regularly feed live animal-based feeds such as daphnia, tubifex worms, and chironomid larvae to enhance nutrition and improve the fish's resistance.
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Bathe the fish in an erythromycin solution at a concentration of 10×10⁻⁶ mg/L for 50–60 minutes.
(3) Treatment Methods:
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Bathe the fish in an erythromycin solution at a concentration of 20×10⁻⁶ mg/L for 40 minutes.
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Alternatively, administer erythromycin at a concentration of (0.4–1.0)×10⁻⁶ mg/L throughout the water, repeating the treatment once after 10 days.
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After bathing the fish in an erythromycin solution at a concentration of 10×10⁻⁶ mg/L, add nitrofurazone to the water at a concentration of (0.5–1.0)×10⁻⁶ mg/L, and repeat the treatment after 10 days.
