“They are safe for aquariums when used properly, but it’s always best to check with the manufacturer of your particular setup,” adds Mowbray. Gorilla Glue is designed to be water-resistant when dry, so use in an aquarium setting must come with some care. PVA Cement might not adhere as well to aquarium glass but is less likely to discolor the water.

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The main ingredient in Gorilla Glue is polyvinyl acetate (PVA), which is chemically related to polyvinyl alcohol (PVOH). It’s unlikely that the PVA will leach into the water because of its chemical bond with the glue. Still, it would be wise to avoid using Gorilla Glue or any other PVA-type glue around the aquatic area of your aquariums.

In a perfect world, you’d never use any adhesive in an aquarium containing living creatures, but as long as you take proper precautions and do your homework before applying anything to ceramic or glass surfaces, you should be good to go.

The best opinion is to err on the side of caution. If you’re not sure, ask! We’re happy to answer any questions you have about aquarium maintenance or construction materials that are safe for your sump or aquarium.

“Gorilla Glue is one of the best glues on the market for woodworking projects, but it’s not necessarily safe for your aquarium,” says Matt Mowbray, owner of The Aquarium Geek online store “It’s important to do your homework before using any adhesive on your aquarium, and the manufacturer’s website is a great place to start.”

In addition, you should never under any circumstances add glue to your aquarium unless it’s diluted with water and the manufacturer specifically states that the product is safe for use in an aquarium. Most of these products are designed for bonding wood, paper, or fabric — not directly to living creatures or live plants.”

If your tank is made of glass and/or has a thin layer of silicone caulk or membrane that you need to adhere something to, then Gorilla Glue is safe for aquariums when used properly.