Maracyn Plus with Biospheres Fish Medication Maracyn Plus multi layered microspheres attach to the fish and breakdown one layer at a time, releasing the antibiotics Contains sulfadimidine and trimethoprin powerful broad spectrum antibiotics that are extremely effective against a variety of bacterial diseases Recommended for the treatment of for mouth fungus, Popeye, dropsy and ulcers The microscopic biospheres attach directly to the fish delivering the medication where it is needed This product weighs 1-gallon