Multi-purpose water conditioner that acts quickly and safely against almost all pathogens in freshwater, e.g. bacterial infections (e.g. Columnaris, Aeromonas, Pseudomonas, fin and gill rot), fungi (e.g. Saprolegnia), single-celled skin parasites (e.g. Ichthyobodo, Chilodonella, Trichodina) and skin and gill worms. The product can also be used to disinfect external wounds and prevents secondary infections.