API® FURAN-2 fish remedy contains two furan compounds to combat a wide variety of gram-positive & gram-negative bacterial diseases, including bacterial gill disease, open red sores (Aeromonas spp.), body slime & eye cloud, black molly disease (Flavobacterium columnaris) and fin & tail rot. For use in both freshwater and saltwater aquariums. This fish remedy will harm the biological filter. Note: This fish remedy will cause a slight discoloration of water which can be removed with activated carbon. Size: 10 packets per box. For each 10 gallons of water, empty one packet directly into aquarium. Repeat dose after 24 hours. Wait another 24 hours then change 25% of the aquarium water. Repeat this treatment for a second time, for a total of 4 doses. Then make a final 25% water change and add fresh activated carbon or replace filter cartridge.