The 5 Best Aquarium Silicones

When it comes to keeping fish as a hobby, one of the best tools you can have at your disposal is silicone.

Say your tank was to have a small leak. Rather than purchasing an entirely new system, you can use silicone to patch the leak, saving you time and money.

You can also use silicone to attach decorations to the bottom of your tank. This is helpful if you have a large fish who knock over or move decorations while swimming.

However, not all silicones are made equal, making it hard to pick the best one for your needs. That’s why we’re here to help!

We’ve created a completed buying guide featuring 5 aquarium silicones that are safe for your fish tank life and easy to use. You’ll also find a FAQ section filled with answers to top questions you may find yourself asking while shopping.

The 5 High-Quality Aquarium Silicones:

1. Aqeuon Aquarium Silicone Sealant

Aqeuon Aquarium Silicone Sealant

This clear aquarium silicone is designed to keep your tank in tip-top shape without taking away the aesthetic appeal. After all, you want to be able to see your fish well at all angles.

You can apply it with a caulk gun for an easy application that’s close to mess-free. Once the silicone is placed, you can also press and mold it into shape so long as you wear nitrile gloves for protection.

Best of all, though, since this is an aquarium specific silicone sealant, you won’t have to worry about your fish. It’s designed to be as sturdy and toxic-free as possible.

The permanent seal is waterproof, and it won’t crack or shrink. This means that after you patch a crack or hole, you won’t have to worry about it any longer.

It’s important to note that many customers have said this product arrives dry. However, it actually has a special opening system that keeps it fresh, which may make it seem dry.

There’s a fine print on the cartridge that tells you to pierce the seal before pressing the trigger on the caulking gun. You can do so by sticking a stiff wire down the opened tip of the cartridge to break the seal to allow the silicone to flow.

  • High strength aquarium silicone creates a permanent, waterproof seal that won’t crack or shrink
  • 100% nontoxic aquarium safe design
  • Able to be applied with a caulk gun for easy, clean application
  • Dries clear for aesthetic appeal
  • Can be molded and patted into placing using nitrile gloves for better, more direct sealing
  • Begins to set after 5 minutes so you will have to work quickly

2. Aquascape Aquarium Safe Silicone

Aquascape Aquarium Safe Silicone

The Aquascape aquarium silicone is designed to be as safe as possible for your fish while not sacrificing durability. Once it is fully cured, it is designed to be nearly toxic-free and safe for both your fish and your aquatic plants.

It is black for easy application. This also means that it will work for rubber pond liners to patch holes and tears.

However, this means that it may not be the best choice for patching a cracked aquarium. This isn’t because it’s less durable, but because it would impair your view of the tank.

This is especially true if the crack is large or spreads across the face of your tank.

It’s made to be durable and long-lasting, but it has a quicker drying speed. However, it does have a strong and unpleasant smell, so you’ll want to keep that in mind while working inside.

Make sure to read the instructions carefully when opening this silicone, especially if you would like to save it and store it for later use. It can be difficult to open, but the instructions will help guide you through the process.

  • Safe for all types of aquatic life including fish and plants
  • Black colored silicone is easy to see for more precise applications
  • Capable of patching holes and tears in rubber pond liner
  • Only requires a small amount to complete a task
  • Quicker drying speed
  • Durable and long-lasting
  • Strong and unpleasant smell

3. Marineland Silicone Squeezer Tubes

Marineland Silicone Squeezer Tubes

Sometimes, you won’t want to buy multiple tubes. To help you, the Marineland aquarium silicone comes in three different sizes.

The silicone dries clear, which helps maintain the aesthetic of your tank. This means no matter what you’re sealing – whether it’s a corner or a crack across the face – you’ll be able to see your fish.

It has a strong vinegar smell at first. However, once the seal cures, this smell will fade.

It’s designed specifically for fish tanks, so you don’t have to worry about your marine life. This silicone is mostly toxic-free.

Just keep in mind that this may not be beginner-friendly. It has difficult instructions on top of being hard to open.

Make sure to read the instructions a few times. Also, be sure to puncture the tube with the right type of tool.

  • Three buying options allow you to pick the right size for your project
  • Clear silicone maintains aesthetic of your tank
  • Odors disappear when the silicone has set
  • Can be used to fix broken aquariums or broken decorations as well as general sealing
  • Designed for fish tanks and mostly toxic-free
  • Difficult instructions
  • Hard to open correctly

4. ASI Clear Aquarium Silicone Sealant

ASI Clear Aquarium Silicone Sealant

One of the biggest issues with using silicone on a tank is handling the sides. If the four vertical edges ever need to have silicone reapplied, it can be a difficult process.

However, the ASI aquarium silicone sealant is designed to combat this issue. It has a non-slump formula that won’t flow or sag when used.

This makes the application easier as well as more beginner-friendly. It’ll also save you from a large mess.

To make it even easier, this aquarium silicone is designed to be used without a primer. This makes the process quicker, which means you’ll get to use your tank sooner.

The seal is durable and permanent. It’s designed to remain strong even when constantly submerged in water.

One of the biggest points to keep in mind with this silicone is the cure time. In order to fully cure, it’ll take 7 to 10 days.

This is something to take into consideration all the time but especially if you’re repairing a tank that already has fish. That means 7 to 10 days that your fish will need a temporary tank.

  • Forms strong cohesive bonds to glass without the need of primers
  • Bonds are unaffected by continuous immersion in water
  • The non-slump sealant that can be applied to vertical surfaces without flowing or sagging
  • Can be used with fresh and saltwater aquariums
  • Designed for fish tanks and mostly toxic-free when fully cured
  • Curing takes 7 to 10 days

5. MOMENTIVE Aquarium Silicone


When you care for fish, you’ll need silicone often, and for a lot of different things. It may be replacing old silicone sealant, patching a hole or crack, fixing decor like aquarium caves, or attaching things to the bottom.

This means that you’ll want an easy to use, multipurpose silicone.

The Momentive aquarium silicone is durable and built to last for many years. It’s strong and can be used for a variety of tasks.

One of its best features is the fact that it can be applied to vertical surfaces as well as overhead surfaces. These are some of the most difficult areas to work with, which is why this is such a great thing.

Most of the time, in these spots, you’ll deal with dripping and sagging. The Momentive silicone will work in a way to help prevent these issues.

You can also use it on a variety of tanks in different sizes. Customers have used this for 65-gallon tanks as well as 135-gallon tanks.

The downside? This silicone takes 7-10 days to cure.

This can be an issue if you’re working with an old tank as you’ll have to rehome your fish for the time being.

  • Can be applied to vertical and overhead surfaces
  • Can be used as a sealant and to fix decorations to the bottom of the tank
  • Durable and built to last
  • Easy to apply and work with
  • Recommended for a variety of tank sizes
  • Takes at least 7 days to cure

Buying Guide – Everything You Need to Know to Pick the Best Aquarium Silicone

There’s a lot that goes into picking the best aquarium silicone to fit your needs. In fact, it may be one of the hardest parts of keeping fish.

However, there’s no need to worry! We’ve answered some of the most asked questions while also walking you through the process of picking a silicone and applying/removing it.

Aquarium Physics – Silicon and Psi

When you’re patching a crack in an aquarium, there’s no doubt that you’re going to want to pick a strong silicone. After all, the last thing you want is to wake up to a flooded fish room.

However, what exactly is strong for silicon?

How strong silicone is determines how much pressure it will be able to uphold. If the pressure outweighs your silicone, you will notice that the leak will persist.

Silicone’s strength is measured in PSI, which stands for pound-force per square inch. You’ll want a silicone with a higher PSI than your tank.

But wait: how do you calculate the PSI for your tank? While it may seem a little intimidating at first – after all, physics is rocket science – there’s a simple method to make it easy.

First, find the height of your tank in feet. You can either use a gauge on the side of the tank and convert it or find a tape measure to do it by hand.

If you’re using the gauge, make sure to convert over any inches. You’ll want to work with a decimal.

For example, if your tank is 3 feet, 5 inches, you’ll want to do something like this: 12 inches + 12 inches + 12 inches + 5 inches = 41 inches. Then, since 1 foot is equal to 12 inches, you’ll divide 41 by 12 for a decimal of 3.42 feet.

Next, you’ll just want to plug that number into a simple formula. It’s accepted that there is 0.433 PSI per foot of water.

This means that your formula will look like PSI= 0.433 x (height of your tank).

For the example above, this would be 0.433 multiplied by 3.42. Thus, for a 3’5” tank, your PSI would be 1.48.

Applying aquarium silicone

How to Apply Aquarium Silicone

Sadly, you won’t be able to apply aquarium silicone to your fish tank as is. Since it will need time to cure, usually 24-72 hours, you’ll have to drain your tank.

Make sure that the area you plan to seal is completely dry and free of any dust or debris.

Then, you load your caulk gun or prepare your tube and apply in smooth motions, careful not to use too much silicone in one area. Certain silicones can be molded and patted out with nitrile gloves for a smoother, cleaner application.

Then, following the instructions unique to your choice of silicone, allow it to cure. This can take a few days but will make sure that your seal won’t budge once the tank is full again.

How to Remove Aquarium Silicone

Like with the application, you’re going to want to work with an empty and dry tank.

After the tank is empty, you’ll want to prepare a dryer for high heat. This will help soften your old silicone seal so that it is easier to remove.

Note, you just need to heat the sealant until it’s softened. You’ll want to avoid melting it as this not only poses a health hazard but also makes it more difficult to remove.

To remove the softened sealant, gently scrape it from the tank using a razor blade. Be careful not to mishandle the blade as you could either harm yourself or damage your tank.

Finally, drench a rough sponge and remove any remaining silicone residue.

Benefits of Aquarium Silicone

If other types of silicone can work – which we’ll discuss further below – then why use aquarium silicone? Turns out, there are a lot of benefits to investing in a fish tank silicone brand, and here are the top ten:

  1. Aquarium silicones are guaranteed to be safe for aquariums. You won’t have to do all the research and second-guessing on ingredients because you know that it will be a fish-friendly silicone brand.
  2. The cure is normally quicker than with regular silicones so you don’t have to worry about leaving your fish out for a long period of time. It’s also made to be more durable.
  3. Aquarium silicones are usually clear, though you can find a few varieties in different colors. This means that it won’t ruin the appearance of your aquarium and will allow for improved visibility.
  4. These solid seals are designed to be waterproof and fully submersible with a high PSI. They are also designed to work in saltwater and freshwater.
  5. Most aquarium silicones are made so you don’t have to use a prime. This makes them more economical as well as beginner-friendly.
  6. Higher level of durability means that aquarium silicones are resistant to shrinking, sagging, and cracking.
  7. Mostly oxic-free design for peace of mind. No more worrying about your fish or plants getting sick from the silicone.
  8. Designed to hold strong even in harsh weather conditions.
  9. Will stop and prevent leaks in your tank. This keeps your fish safe and your house dry.
  10. Easy to use. Most come with easy to follow instructions and can be used in a caulk gun.

Is regular silicone safe for aquariums?

Sealing fish tank

This really depends on your definition of ‘regular silicone’. While it doesn’t have to be aquarium specific silicone to be safe, there are stricter guidelines you’ll need to stick to.

Regular silicones are built with different formulas depending on the brand, strength, and purpose. As a result, it’s not a one size fits all type of product, and just because one silicone works doesn’t mean another one will.

The best thing that you can do is learn what kind of silicone is safe.

What kind of silicone is safe for aquariums?

It’s a bit easier to talk about what kind of silicone isn’t safe, really. You see, you can use any type of 100% silicone so long as it doesn’t have certain additives.

These additives include things such as fungicides and mildew or mold inhibitors. While these are great for other projects, they have the ability to harm or even kill your aquatic life.

If you’re worried about picking the wrong thing, aquarium silicone is always a safe option.

Is silicone sealant toxic to humans?

When dealing with things like silicone, there’s always some possibility that it contains harmful chemicals. These should not touch your bare skin or eyes, nor should it be ingested.

However, the safest option is 100% silicone. This is the purest form available and is mostly free more those harmful chemicals.

No matter what, though, also use caution. Wear gloves and only use silicone in a well-ventilated area.

Is silicone toxic to fish?

It can be!

While pure silicone itself is fairly harmless, it’s nearly impossible to find a version completely untouched by chemicals. This means there is a possibility of all silicones being toxic.

However, most are regulated to be as safe as possible for marine use. Just make sure to pick one that doesn’t have known toxins such as mold inhibitors.

Is GE silicone sealant safe for aquariums?

Even within a single brand, different varieties of silicones can be made different. This is why it’s so important to check the ingredients and do your research.

Remember, you want to avoid mildew and mold inhibitors.

In looking at other customers’ experiences, some GE silicones have worked, while others have been detrimental to fish life.

How long does aquarium silicone last?

How long an aquarium silicone will last depends on a lot of factors. This includes things such as the PSI of the silicone and the air conditions (such as humidity) in your home.

As a general rule of thumb, however, you should never leave silicone on for more than ten years. Even if it is still working after a decade, it’ll be weaker and more likely to burst.

The best way to ensure that your fish are also safe is to change your silicone every five or so years. Make sure to remove all of the old silicone using the process above to ensure the new silicone can stick well.

What’s the difference between aquarium silicone and regular silicone?

While there are several differences between aquarium silicones and regular silicones, which we will discuss, the biggest is the price tag. There are plenty of regular silicones that are safe for aquariums without being specially marketed for aquariums.

There’s also an extra sense of safety.

When you buy an aquarium silicone, you know it’s going to be safe for your fish. You’ll need to do more research with a regular silicone to make sure it’s non-toxic.


When you’re dealing with chemicals and your fish, it can be hard to know the right steps to take. This is especially true for beginner fish owners.

That’s why we made this guide. We care for your fish and their safety just like you, and so we wanted to help you make well-informed choices about silicone.

There are several types of silicone available for sale, and not all of them are created equal. While most will work well to seal your aquarium, there are some types that are harmful.

However, as long as you do your research before purchasing, and avoid certain ingredients, shopping doesn’t have to be scary. Best of all, though, when it’s all over, you usually don’t have to worry about it for another five years!

That’s half a decade of watching knowing your beloved fish and aquatic life are safe from leaks and cracks.