Metronidazole is an effective and safe treatment for several protozoan and anaerobic bacterial diseases of fish (Cryptocaryon, Hexamita, Ichthyophthirius). It does not adversely affect the filter bed and is easily removed with carbon. There is little danger of overdosing. Usual dose is 125 mg/10 gallons.
Use 12 measures (each about 100 mg) for every 40 L (10 gallons). Measurer included. Repeat every 2 days until symptoms disappear. Turn off UV, ozone, and chemical filtration. To feed, blend 1 measure with about 1 tablespoon of frozen food paste. To minimize loss during feeding use with Focus. Food may be refrozen.