Fish and filter safe parasite control;The only fish and filter safe aldehyde based parasite control product available (for parasites on fish);Employs a proprietary, synergistic blend of aldehydes, malachite green, and fish protective polymers;Effectively and efficiently eradicates many ectoparasites (ich, etc) and external fungal, bacterial, and viral lesions (fin rot);250 milliliters treats 500 US gallons