Formulated for fresh or saltwater aquariums, this silicone sealant adheres to glass without primers. When fully cured, this waterproof 100% silicone sealant is non-toxic to fish after curing, is resistant to weathering, airborne chemicals and UV radiation. ASI Aquarium Silicone Sealant is a non-slump sealant and can be easily applied to a vertical surface and will not flow or sag. Will not crack or shrink.