The safest types of glues for aquariums are cyanoacrylate super glues, silicone, and epoxy glues. 

Here are the two main features of aquarium-safe glues:

1. They become inert in water, moisture, or wet surface
2. They don’t cloud up the tank 

If you want to discover more about the glue types that are the best and safest for aquariums and how to use them for the best results properly, then keep reading. 

How To Know If The Glue Is Safe For Aquariums

Let’s examine the two main aspects that make glues safe for aquariums. 

1. Inert in water 
2. Don’t cloud the tank

Why are these features important when choosing glue for your aquarium?

Here is why glue is only safe for the aquarium if it is inert after it dries and comes in contact with the underwater environment. 

If the glue doesn’t become inert after it dries and you let it come in contact with the water, this will release fumes that can be toxic to the whole environment, including the water, the plants, and the fish.

Here, we will tie in the second safety feature for aquarium glues. 

If the glue is inert, it shouldn’t cloud up your tank. 

If this has happened in the past (or is happening in the present), the glue is releasing harmful substances into the aqua space. 

The Aquarium Safe Types Of Glues And How To Use Them

There are three main types of glues that are generally safe for aquariums. 

These are:

• Super glue 
• Silicone glue 
• Epoxy glue 

Super Glue

If you want to use super glue for your aquarium, only choose cyanoacrylate-based ones.

Super glue is:

• Very fast-drying
• Easy to use
• Effective
• Long-lasting 

Now, super glue should not be used as a gap filler, sealant, or for fixing big cracks in the glass. 

This adhesive is best suited for gluing and securing ornamental pieces, such as plants, rocks, and wood items. 

Do not glue items inside the water or aquarium. 

Only glue outside the water and add the items inside it after it has fully cured to keep it safe for the environment. 

Follow these steps to use super glue for your aquarium:

1. Prepare the surfaces you want to glue – make sure they are clean, free of stains and dust, and fully dry using a clean cloth and warm soapy water 
2. Apply a thin layer of superglue to the surface that you want to bond together
3. Align the two surfaces (plant and rock, plant and wood) and firmly press them together
4. Keep applying the pressure carefully for a minimum of 60 seconds 
5. Let the glue cure for 24 hours – use tape, wire, or other tools to keep the two surfaces secured in place
6. After 24 hours, remove the tape
7. You can add the decor inside the aquarium 

You can work with the following:

• Super Glue
  • It doesn’t bond as well on very smooth surfaces – you need to create a better adhesion

• Gorilla Glue
  • It can withstand temperature fluctuations 

• Krazy Glue
  • Works best on rougher surfaces 

• Reef Glue
  • Great adhesion properties
  • Long-lasting 

Silicone Glue 

If you need to fix water leaks, or fill gaps, then silicone sealant is your best aquarium-safe choice. 

You can also use a silicone sealant for aqua space decor projects but also cracks in your tank. 

Aquarium-safe silicone sealant has the following features:

• It is flexible
• Dries clear 
• Doesn’t release toxic fumes 
• It is long-lasting 

Follow these steps to accurately and effectively use a silicone sealant for your aquarium:

1. Prepare the surface – the surface you need to apply the silicone sealant to needs to be clean and dry
2. Apply the silicone sealant to the surface to fully cover the gap or crack
3. Let the silicone sealant fully cure before adding the water, fish, plants, and any other items back into the tank 

Depending on the brand of the silicone sealant, the curing time may differ – it can be 24-48 hours or multiple days. 

Read the manufacturer’s instructions and wait out the curing process. 

Don’t try to cut corners, as tempting as that may be.

Epoxy Glue

You can use epoxy glue for the following needs when it comes to your aquarium:

• To bond rocks to each other firmly 
• To repair pipe leaks 
• To repair other equipment issues 

You can use epoxy glue following the same steps as super glue. 

Make sure you prepare the surfaces, apply the glue, and wait for the glue to cure fully. 

Epoxy glue for aquariums:

• Is flexible 
• Is powerful 
• It dries quickly 
• Fills small spaces and gaps 
• Is waterproof 
• Protects sealed surfaces from unwanted pathogens 

The Best Aquarium Safe Glue

Above, we talked about the types of glues that are safe for aquariums and how to use them. 

In this section, we will talk about the best aquarium-safe products and their highlights, so you know what to expect from each before committing to one. 

Depending on what you want to accomplish with your aquarium, one glue may be better than another. 

So here they are. 

Seachem Reef Glue 

Seachem Reef Glue is a cyanoacrylate adhesive in a gel format. 

It bonds within seconds, and thanks to its gel formula, it doesn’t create a mess or unwanted spills when you apply it. 

This glue is easy to apply, and it dries clear. 

Aquastik Coralline Red

This aquarium glue is a crowd favorite; you won’t be surprised why. 

Aquastik Coralline Red color matches live rock and coralline algae because of its red color. 

Its red color makes this aquarium glue unique, as most adhesives are clear, white, or greyish when they dry and fully cure. 

It is an underwater epoxy putty for reef and marine aquariums. 

What to know about Aquastik Coralline Red:

• It is easy to use
• It hardens fast 

Instant Ocean Aquarium 

Instant Ocean is glue with an aquarium system that bonds corals, plants, live rock, and slate. 

This glue is:

• Ideal for marine and freshwater
• Easy to use 
• Safe for all fish and invertebrates 
• Offers superior bonding –
• Dries white 
• It can be sanded, filled, and drilled once it is fully dry

With this adhesive, you can create:

• Cliffs
• Caves 
• Walls
• Steps 

Seachem Flourish Glue

Flourish Glue is a cyanoacrylate adhesive that bonds within seconds. 

This glue can attach moss and plants to rocks and driftwood. 

Marineland Aquarium Sealant

Here is what you need to know about this silicone sealant:

• It is 100% clear silicone rubber
• Stays flexible 
• 100% waterproof 
• Will not shrink 
• Doesn’t crack 
• It is harmless to fish 

This silicone sealant is ideal for repairing leaky spots or broken decorations. 

Before you apply this silicone sealant to the surface, make sure the surface is clean and fully dry. 

Aqueon Silicone Glue

Here is another silicone sealant made specifically for aquariums. 

It is easy to apply and is waterproof. 

This silicone sealant for aquariums:

• Ideal to stop leaks 
• Is high strength 
• Offers a permanent seal 
• It won’t crack 
• It won’t shrink 
• It is non-toxic 

Gorilla Super Glue Gel

The gel format of this super glue offers no gun control, even on vertical surfaces. 

Here is all you need to know about this glue:

• It comes with an anti clog cap to keep the glue from drying out
• It is formulated for increased strength and impact resistance 
• It dries within 10-45 seconds 
• No clamping required 

Loctite Super Glue Gel Ultra Gel Control

This is Loctite’s most durable superglue. 

Loctite super glue gel ultra gel control:

• Is flexible
• Resists water, impact, shock, vibration, and harsh conditions 
• No drip or run formula 
• Great for vertical application 
• Maximum control accuracy 
• Easy application 
• Dries transparent 
• Doesn’t require clamping 

Boston Aqua Farms Reef Glue Gel

The unique feature of this glue for aquariums is that you can safely apply it underwater. 

It dries clear. 

How To Build A Rock Aquascape With Glue: Best Tips

Follow these steps to easily and effectively build a rock aquascape that will last:

1. Assemble the rocks before you glue them together to check how they fit – if needed, chip off spots to make the surfaces fit better together and to enable the glue to form a stronger bond 
2. Clean and fully dry the rocks
3. Apply the glue to one surface
4. Align and firmly press the two rocks together and hold them secured in place for a minimum of 60 seconds 
5. Repeat these steps until you have glued all your rocks together 
6. Use tape or a wire to keep the rocks securely in place while the glue sets and cures 
7. Allow the glue to cure for 24 hours 
8. Remove the tape or wire
9. Place your rocks in the aquarium 

Conclusion

The safest and most commonly used types of adhesives are the following:

• Silicone sealant
• Cyanoacrylate-based super glue
• Epoxy glue