First, symptoms: sick fish will rub hard objects with their bodies, hoping to get rid of nasty pathogens. Many small white spots can be seen on the body surface, fins and gills of sick fish. Sick fish are thin, floating on the water or in the corner of the cluster, and rarely move. In the later stage, the body surface is covered with a white film, with increased mucus and dull body color.

Second, prevention and control:

1. Soak in 2ppm methyl blue solution for 6 hours every day.

2. Mixed treatment with 0.05ppm malachite green and 25ppm formaldehyde solution has good curative effect.