API Goldfish Aquarium Cleaner, 4-oz bottle; Cleaning your goldfish's home will be easier than ever with a Goldfish Aquarium Cleaner from API. Made with beneficial bacteria cultures, this unique cleaner is a quick and effortless way to naturally break down the junk floating around your aquarium—even the stuff you can't see. Waste, uneaten food, and other organic matter can work together to fog your pals' tank with toxic junk, which may cause stress, illness and ultimately harm or kill your fish. But API's aquarium cleaner helps to clean gravel, works to remove sludge and help to reduce ammonia and nitrite levels as a result! Use once-a-week, during your regular water change, to help keep your fish's environment clean and healthy.