Seachem's Aquarium Sealant is a 100% RTV Silicone for sealing and repairing aquariums. It is formulated to provide excellent adhesion and tensile strength with permanent flexibility. It is safe for aquatic life in both freshwater and saltwater.
Fast postage and good price. Haven't used yet to fix the crack in our aqua eco 47 fish tank plastic light cover. Handy as you can't replace these. Safe for fish.