Aqueon Aquarium Silicone Sealant formulated with 100% silicone, it forms a clear waterproof seal to stop leaks, and does not crack or shrink when applied. It's actually the same high-strength silicone that's used to make new aquariums so it's a long-lasting, professional-grade bond you can trust. And since it's non-toxic, it won't harm plants or fish and works in both freshwater and marine aquariums. Plus, the formula is proudly made in the USA. Key Benefits Made with 100% silicone to seal aquariums for a leak-proof, water-proof finish. High-strength silicone creates a permanent seal that will not crack or shrink. It's the same grade of silicone used to seal new aquariums so you can expect professional-grade quality. Formulated to be non-toxic so it's perfect for use on all aquariums, including freshwater and marine aquariums. Made in the USA and comes in one tube or 2-pack options to fit your needs.