Is Hot Glue Aquarium safe?

One really tricky topic when it comes to fixing or setting up a fish tank is what materials should be used. Aside from the glass, it can be quite hard to find the right adhesive to stick everything together. This is where hot glue comes into the picture. However, there is still a very critical question that tags along when talking about the use of hot glue, “is it safe?”

The last thing pet owners want to do is make something that could potentially harm their fish, and this is why it is very important to choose which materials to use when setting up a tank. Is hot glue safe? Is it effective?

Short Answer

The more direct answer is that no, hot glue is not actually safe. Although it might be labeled as non-toxic, this is not always the case with some brands. It is also very difficult to tell which brands are safe and which brands can be harmful for the fish when it comes to hot glue.

Long Answer

The thing about hot glue is that it isn’t designed for fish tanks but rather for a number of other general purposes. Hot glue is considered a “quick-fix” and not technically an ultimate solution. While it might work a few times over, the problem with hot glue is that it also won’t hold over time.

For those that might need a quick or temporary fix before buying an actual solvent, hot glue is usually their go-to, but it is not advised. This is why, for those with fish tanks at home, it is important to have the right materials around just in case you might need an adhesive to glue things together.

Alternatives to Hot Glue

There are a few alternatives that have proven themselves not only effective but also safe for the fish. These alternatives have proven their worth and are the first choices for professional fish owners. Here are the alternatives:


To be more specific, the GE Silicone 1 for windows and doors is pretty safe. Make sure to read the label for no additives. The good thing about silicone is that some brands specifically label their product “safe for aquariums.”

There might be some cheaper local options for these, which makes the selection process much easier. Learning how to use silicone is relatively easy since it is already a glue-like substance except a bit thicker like toothpaste. It is essential to wait 24 hours to one week, depending on the size of the tank.

If you are interested, you can find here a detailed test about aquarium safe silicone.


When using cement, always make sure that everything is dry and clean before putting the fish in! One massive problem with some fish owners using cement is that they do not thoroughly wash and drain out the residue coming from the cement. Cement could also be a very affordable way to construct certain fixtures for the fish tank. Watch out for the words “water thin” and “solvent cement” to make sure to get a safe one.

The danger of not thoroughly washing and draining the fish tank is that small residue, and the fish might swallow other small particles. To get rid of the residue, make sure to fill and drain the aquarium a few times and have the filtration system run for 24 hours.

Water Glue

A specific type of glue is actually safe for fish, and these are called “reef glues.” Reef glues work precisely how they are named and are for underwater purposes. These, however, can’t really handle big jobs but rather the smaller and more meticulous jobs that need to be done.

This type of glue would be perfect for reefs, holding small parts together, and other small figurines and details you would want to keep in place. It might not be capable of handling heavy-duty adhesive work like for bigger rocks, wood, and other structures.

Why is Hot Glue not Aquarium-Safe?

There are a few reasons why hot glue is not safe, and although there are some hobbyists who claim it is, dealing with the additional risk isn’t worth it. As an aquarium owner, providing the safest habitat for fishes is a top priority and should not be taken lightly. Here are a few reasons why they aren’t safe.


The thing about hot glue is that it does not technically seep in but rather creates a plastic-like material in between the two things that it is trying to stick together. Although hot glue might be effective at first, it won’t hold for long, especially if it is being moved consistently.

String-like Properties

The thing about hot glue is that it is not always solid like a ball but could also have some string-like properties once stretched. The hot glue “string” could then be swallowed by the fish which would end up within their organs and potentially be a serious issue.


Hot glue usually ends up being rather messy and a significant amount of glue is required just to stick two things together. For bigger things that need to stick together, the size of the glue, when hardened, becomes bigger. This would then make for yet another unsafe particle within the fish tank.

Is Hot Glue toxic for Aquariums?

While there might be hot glues that are non-toxic, most of the standard ones might contain harmful chemicals that would potentially harm the fish. The risk is even greater for those using cheap glue sticks since they usually contain cheaper alternatives for the chemicals that make the adhesive.

What is the Best Hot Glue Aquarium Alternative?

It is important to look beyond “what” to use and “what type” of adhesive to use. Certain adhesives label themselves “safe for aquariums” and are generally the best to use. Of course, make sure to research the brand and the product before buying it. The reviews themselves will tell if the product is indeed useful or not.

Conclusion – Is Hot Glue Aquarium-safe?

The safety of an aquarium is generally dependent on both how the fish tank was built and what materials were used to build it. Make sure to choose only quality. Fish, like every creature, need their own habitat to be able to grow healthily. Making the perfect habitat means putting certain pieces together, and to do this, you’ll need the right adhesive. Make sure to use one that is not only effective but also safe for the fish inside. Create not just a beautiful tank but a safe one too.


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