For freshwater & saltwater aquariums Fish & filter safe parasite control Seachem DOES NOT guarantee this product is safe for invertebrates and plants Use one capful for every 10 gallons. Repeat daily as required as long as fish show no stress. The entire 500 ml bottle will treat 1,000 gallons. Seachem ParaGuard is the only fish and filter safe aldehyde based (10% by weight) parasite control product available. Unlike highly toxic and difficult to use formalin based medications, ParaGuard contains no formaldehyde or methanol and will not alter pH. ParaGuard employs a proprietary, synergistic blend of aldehydes, malachite green, and fish protective polymers that effectively and efficiently eradicates many ectoparasites on fish (e.g. ich, etc.) and external fungal/bacterial/viral lesions (e.g., fin rot). It is particularly useful in hospital and receiving tanks for new fish and whenever new fish are introduced to a community tank.