Is the Common Super Glue Safe for Use in Aquariums?

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It’s understandable if you think that using glue around fish is a bad idea.

You want to build the aquascape as you’ve imagined it but an aquarium safe glue for rocks just seems counterintuitive.

I remember thinking “this can’t be safe, there are tons of crazy stuff in it!”.

I mean, what if it spreads in the water and destroys all life present there?

Is there a super glue aquarium plants would even tolerate?

Let me start with a very short anecdote on super glue.

Unfortunately, it seemed like a really handy solution for my aquascaping. It would be very convenient if I could just use it here and there.

I was obligated to do some heavy research on the subject.

I went through countless authoritative articles, asked my friends that owned fish tanks for their experience and wisdom.

I even significantly improved my knowledge of chemistry.

The good news is I now want to share that knowledge with others that are asking the same questions.

I’ve learned a ton and I’ve digested that info for my fellow aquarists below.

So is using super glue harmless to your aquariums?

Essentially water helps the glue to cure even faster, because of the chemical bonds that form upon contact.

Here’s what happens with the super glue in an aquarium and if that makes it safe:

Super glue is safe for use in fish tanks because it becomes completely inert when moist or wet. The main active ingredient of the glue is Cyanoacrylate. When in contact with water it forms strong and stable bonds. Essentially, it polymerizes in 30 to 45 seconds. Cyanoacrylate is by definition an aquarium safe glue, as water is an accelerant (or catalyst) of the curing process. Wait out the curing for 5 to 7 minutes and then put the glued object inside the tank.

On some super glues you may read “ethyl Cyanoacrylate” but that’s just a slightly different chemical formula.

The latter is used in skin sealing for animals and even people during surgery.

It may sound like a scary name at first read but it has nothing to do with the toxicity of Cyanide.

The Gorilla gel super glue can be used as aquarium glue. Here’s a link to Amazon where I’m showing you the exact ethyl cyanoacrylate gel version of that.

For the record, hot glue is also safe for aquarium use as long as it has no additives and mold inhibitors. However, bear in mind that it’s not a good long-term adhesive for underwater use, whereas using super glue is both safe and efficient.

Where to use super glue in my aquarium?

Super glue is very strong and it becomes almost as hard as a rock.

However, It will be brittle and it will leave small gaps, which does not make it a good sealant.

This exact property results in it being applicable to small areas only.

Though it is an aquarium-safe glue for decor, it’s only good for certain types of decor.

Super glue gel (less mess) is perfect for fixing the following items in your fish tank:

  • aquatic plants to rocks
  • rocks to rocks
  • coral frags to rock (link is to my Hammer coral placement guide)
  • live rock to live rock

Super glue is a fantastic way to glue down aquarium plants or corals while creating your desired aquascape. However, you can also use it for gluing aquarium rocks together if it makes sense for your setup.

My tips on using super glue for fish tank purposes

I’d just LOVE it if I could save you the time and mistakes I did when I tried it out the first time.

And the second time. And the third…

From my experience, you can’t go wrong if you follow a couple of very simple rules.

Here’s what I’ve learned about using super glue in my tanks:

  • Use the gel version – you don’t want to use the liquid form as it will get messy, trust me.

    The gel is easier to apply and control.

    I like to buy them in bulk and forget about them.

  • Don’t use it for underwater gluing – as mentioned above the active ingredient of the adhesive cures really fast when in contact with water.

    You could waste the whole tube of the stuff and still achieve a 0 effect.

    Whatever it is that you’re attempting to glue MUST be dry.

    But as we all know, it’s not fun to risk ruining rock work by pulling the bottom ones out, disturbing our fish, and whatnot.

    If you really insist on doing the gluing underwater I have used the following method: I glue whatever plants to a really small( 1.5 to 2 inches wide) rock outside the aquarium.

    I wait it out and then firmly grip at the base of the already fixed plant.

    Then I apply LIBERAL amounts of the gel on the bottom of this small rock, being really careful not to glue my own fingers to it.

    After that, I have around 30 seconds to dunk the piece in the water and play around with the angles.

    When I glue to driftwood, say, I use a small piece of driftwood outside the tank.

    Don’t ever use latex gloves in your tank!

  • All brands are suitable for use – it does not matter if it’s Gorilla, Krazy etc.

Where not to use super glue in my tank

As the glue is rigid it will not be able to maintain a seal.

It does not do well where there is flexing (when polymerized it won’t have even the slightest elasticity).

Don’t use it as a sealant as it will form microscopic gaps and won’t maintain a thick, impenetrable layer.

Therefore it’s not a good choice for holding water inside your tank.

For sealing you need an aquarium-safe silicone sealant.

I usually use Aqueon’s fish tank sealant for small (and, frankly, medium-sized) jobs and it works pretty well.

Amazon has it for under $13.


Super glue is not only safe for your marine and freshwater aquariums, but it is also a must-have for every fish-keeping enthusiast.

It’s really efficient for crafting nifty aqua decor and it is particularly easy to use.

What about your super glue adventures?

Tell me in the comments.

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will stratford

Thanks for the info, much appreciated


THANK YOU! I was doing a water change. I noticed a couple of my fake plants had a tiny piece of metal sticking up from missing leafs, and rust! So now Im fretting about rust in my tank. Im also fretting about buying an entire tube of expensive Aquarium Glue just for 2 micro-tiny spots, I finished cleaning up the tank and let the plants dry out over night. Jumped on the web this morning to look for safe alternative glues to use on aquariums and your article popped right up. The problem with buying a tube of aquarium glue… Read more »


Thanks for the info. I knew it was used, but couldn’t understand how! Now I will feel safe using it. I’ll subscribe for the future.🐠


My LFS suggested I glue a rock to my back wall using 2 little fishies coraffix gel. They suggested I put a large glob on the rock then press it into the glass (under water) honestly messier then I had imagined but seems to have done the job. Now to wait and see if I have any negative side effects. I’ll let you know.


Be careful putting rocks up against glass as it can create pressure points and crack it.


Thank you for the information very helpful, now if i can just get my frags to stay were i glue them i will be a happy soul 🙂


hi, I like just wanted to know if I could use Krazy Glue for gluing some plants to my new rocks but just wanted to make use that specific glue is fine? 🙂

Dwayne Gitter



I superglued a plastic chopstick to a take away fork to use as a sand rake. I’d buy one but it’s out of my price range atm. I just hope its strong enough.


Thank you!!


Great Info, very late to reply but i assume that i can use this method to add mesh to cover the intake slots on my internal filters? I have 3 filters that came with my tank but want to keep small fish (tetras, danios) and have heard horror stories of people finding them dead inside the intake If i glueit to the outside that should be safe right?