Aqueon Silicone 3-oz Aquarium Sealant creates a waterproof seal to stop tank leaks safely and effectively. Made with 100% silicone, this high-strength sealant has the same strength as the silicone used to manufacture new aquariums. The long-lasting bonding power creates a permanent seal that stays flexible so it won’t crack or shrink. It’s easy to apply and non-toxic, so it’s safe for freshwater and saltwater aquariums.