Maracyn's active ingredient is an antibiotic called erythromycin. It provides relief from bacterial infections such as body fungus, gill disease, fin rot and popeye in freshwater aquariums.

The savings come in the large 24 pack or larger over the traditional API Erythromycin. Each packet treats 10 gallons. The 60 gram bulk container treats 1,000 gallons. We recommend using an airstone in the aquarium when treating with Maracyn.