No, we do not recommend TotalBoat Thixo thickened epoxy adhesive for use in an aquarium because if there is any inconsistency in the ratio of the mixed components, it may not be safe for some animals and plants. Instead, use an epoxy adhesive that is deemed safe for use in an aquarium, such as certain types of silicones, premixed epoxy putty sticks, or cyanoacrylate adhesives.