NT Labs Koi Care Formaldehyde 30% is effective against protozoan parasites and flukes. It is especially useful in treating flukes because of it's ability to penetrate mucus and reach the parasites that would otherwise be protected from other bath treatments. Caution: Formaldehyde is a hazardous chemical and should be handled with great care please read the warnings on the label carefully. Also available in 250ml - See model YR113
