API ALGAEFIX algae control effectively controls many types of algae in aquariums and will not harm to your fish or plants when used as directed. You can use ALGAEFIX algae control as part of your aquarium maintenance routine to control the formation of new algae. Weekly doses will control algae growth and reduce aquarium maintenance. CAUTION: Do not use with freshwater crustaceans including shrimp, crabs, and lobsters.