Is the Common Super Glue Safe for Use in Aquariums?

super glue safe for aquariums header

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.

Conclusion

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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34 thoughts on “Is the Common Super Glue Safe for Use in Aquariums?”

  1. so i tried to use the gorilla gel to glue anubias to rock.. i found that the glue glob i used was a bit too thick and wouldnt dry.. worried that i would kill the plants by having them out of water for too long i put them in the tank. so your saying that this is ok even though it had not fully cured outside the tank and poses no threat to my fish? i was tempted to throw the plants and rock to be safe

    • Hi Christ,

      Having your plants out of the water for 5 to 7 minutes would not kill them. You should’ve asked here, before doing anything.

      Also, the will cure, no worries.

      Best,
      Momchil

  2. I’m so throughly grateful that I stumbled upon your article on super glue and fish. You saved me so much time and headache. Following your guidelines (which by the way you presented beautifully and succinctly) I was able to achieve what I was after in my own aquarium. I can attest to the fact that your research and trial by error information is invaluable and absolutely correct. My tank decor is exactly what I had in mind for so long but was scratching my head as to how I’d go about it. So once again thank you so very much.

    • Thanks so much for this!!!

      Your comment made my day!

  3. Is E6000 safe to use for affixing fish tank decor?

    • Hi,

      E6000 has different active ingredients than the regular super glue and as far as I understand it can be more harmful. It appears that once it cures it can be extremely chemically stable though, which is more important when using something in your fish tank.

      I would use it in my aquarium, but after making sure it’s cured.

  4. Thank you! I was trying to fix the broken frame of a breeder net. The superglue didn’t actually adhere well to the frame that was broken, but it’s definitely all over it. I was worried about putting the wonky net back in the tank. I am expecting corydoras eggs to hatch in 2 days – no time to get another net! So this info was reassuring. Whew.

    • Hi Phil,

      This is it, yes. You can absolutely glue Anubias with it.

      Happy aquarium keeping!

      – Momchil

  5. Hi can i use the glue in an already established tank. I want to add anubias to a driftwood i already have inside the tank. I dont want to take it out and disturb the setup as its home for my shrimps. Pls suggest if its a good idea to apply glue to the anubias rhizome and stick to the driftwood inside the water.

    • Hi,

      You could try but mind that the glue will start curing as soon as it touches the water. The rhizome idea is fine in my opinion.

  6. I want to grow moss on rocks and wood and a friend suggested super glue. You mention that both surfaces should be dry. Should I just dry the moss pieces with tissue paper and then glue to a rock and place it in the tank after several minutes?
    If that does work how will the moss grow further on the rock or wood.
    I tried tying some moss with string on rocks and wood but it never grew and died. Any advice you could give me please.
    Also I would like to thank you for the superb article you wrote. Must have taken a lot of time to research.
    So thanks again. Take care.
    Shabbir

  7. Thank you for this info. It was just what I needed. Have built a bowl to use as a bird bath and watering station and gluing shells and rock on the edges and adding a solar powered fountain. Just wanted the birds to be safe too!

    • Thanks for sharing!

      Sounds like a fantastic little setup, Nell.

      Well done!

  8. Thanks for all the info!
    How well would super glue work with gluing moss to a piece of drift wood?

    • That would work no problem.

      Good luck!

  9. Is hot glue safe as well???

    • Hi Mara,

      Yes, it’s safe as long as it’s pure melted plastic with no mold additives. In terms of long-term efficiency, however, it does not stand a chance against super glue or aquarium-grade sillicone.

      Hope this helps!

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