Has superior bonding ability that allows you to create steps, caves, cliffs and walls for aquarium pets to enjoy. It bonds to all types of materials, to include rocks, coral, slate and many more. HoldFasT is non toxic to fish and invertebrates and is great for use in freshwater or saltwater. HoldFasT mixes easily in the palm of your hand. No messy liquids to measure and mix just break off a piece, knead it in your hand until it turns white and it is ready to bond.