Just a quick query as they love to drink from our pond
When I used to work in a fish lab we used copper sulphate to treat white-spot. Toxic, supposedly, but it didn't seem to do the fish any harm.
Mind you this was a LONG time ago and there might be a less unpleasant modern treatment. Blimey. 35 years ago in fact !!!
Could you email the manufacturer, Rubyleaf?