Maracyn make use of a revolutionary technology that delivers the antibiotic directly to the fish, Contains two powerful broad-spectrum antibiotics that are effective against the bacteria that cause Fin and Tail rot, Popeye, Dropsy, Ulcers and Mouth and Body "Fungus", As the bio spheres attach to the fish, they form a protective medicated layer over the fish"s skin that kills the infecting bacteria and prevents re-infection, For use in fresh and saltwater tanks, 4 oz, SKU: RYLHC3292