Controls many types of algae in freshwater aquariums containing live plants and fish. Contains 4.5 Percent Poly{oxyethylene(Dimethyliminio)ethylene(Dimethyliminio)ethylene Dichloride}. Do Not Use In Aquariums Containing Freshwater Crustaceans Such As Crab, Lobster, And Shrimp. 16 OUNCES