Best Heater For 5 Gallon Betta Tank

We cover our top 7 picks that we feel qualify as the best heaters for 5 gallon Betta tanks, we review each of them in detail covering features, pros and cons to help you decide on the right option for your aquarium.

Betta fish do like their water to be warm, slightly above room temperature. Seeing as this cannot be achieved by simply letting the tank sit in a room, you will probably need a good little water heater for your tank.

Today we want to look at some options which we feel qualify as some of the best heaters for 5 gallon Betta tanks (this one is our top pick). Let’s get right to it and take a look at our Top 7 picks that we felt are worth a mention.

Tetra HT Submersible Our Top Pick 9.6/10
Penn Plax Submersible 25 Watts 9.3/10
Marina Submersible 25 Watts 9.3/10

Best Heater For 5 Gallon Betta Tanks: Top 7

Here are our top 7 picks with a detailed overview of each. If you need help with tank suggestions then this post will help you.

1. Tetra HT Submersible Aquarium Heater

The Tetra HT Submersible heater has an indicator light which turns on whenever the heater is on. This means that you will never mistake this heater for being on or off when the opposite is the case. The light is red when heating and turns green when the ideal temperature has been achieved.

This heater features a built in thermostat which maintains water temperature at 78 degrees. Some people don’t like how you cannot adjust this heater, but others like it for this very reason. Simply put it in the water, turn it on, and it is good to go. This particular heater is more than ideal for aquariums between 2 and 10 gallons in size, especially if the tank has a good lid or hood.

It’s a cool heater because it can be put in an aquarium both vertically and horizontally. It is very easy to install, plus it is fairly small, so it does not take up very much room inside of the tank. Simply use the suction cup to attach it to the interior wall of your aquarium.

Be sure to place the heater inside of the water before plugging it in. This is a very simple and basic heater. It does not have many fancy features, but it does the job just fine.


  • No adjustments required.
  • Easy to install.
  • Does not take up much space.
  • Has an internal thermometer.
  • Can be installed vertically or horizontally.
  • Good for aquariums between 2 and 10 gallons.


  • Cannot be changed from 78 degrees.

See more info and pricing at Amazon

2. Penn Plax Aquarium Heater

This particular one is a 25 watt heater that is ideal for aquariums up to 5 gallons in size. That being said, this heater does also come in several other versions, each of which is ideal for larger aquariums. Many people hail the Penn Plax Aquarium Heater as being one of the most accurate around, being able to heat the water and maintain the temperature within 1 degree, which is of course quite important.

Now, the Penn Plax heater does have a preset temperature of 76 degrees, but you can actually program it to be warmer or colder, which is pretty convenient if 76 degrees is not what you need.

Being easily programmable is a big bonus that you get with this particular aquarium heater. On a side note, what many people will like is that this thermometer can be switched between Fahrenheit and Celsius for ease of use.

This heater is fully submersible, so you know that water will not damage it. It is a fairly simple water heater in the sense that you just plug it in and it is good to go. Just be sure that it is fully submerged underwater before plugging it in. We do like how this model is very easy to install.

Simply use the included suction cup to place it on an interior wall of your aquarium. It is fairly space friendly and can be installed either vertically or horizontally.

It is also a good option because it can be used for both saltwater and freshwater aquariums.


  • Space saver.
  • Easy to use.
  • Plug in and go.
  • Can be programmed.
  • Comes in F and C.
  • Suction cup for easy installation.
  • Very accurate.
  • Good for salt and freshwater.


  • Not too durable – fairly short lifespan.

See more info and pricing at Amazon

3. Fluval Marina Submersible Heater for Aquarium

This next water heater is classified as a mini heater, which based on its size is definitely true. Lots of people really like the Fluval Marina due to its very small size.

Small aquariums are already tightly pressed for space, so having a heater that preserves as much prime real estate as possible is always handy.

The Fluval Marina heater is fully submersible and has a totally waterproof seal to make sure that the internal components do not suffer from any kind of water damage. It also has an impact resistant design.

This is important in case you drop the thing by accident or if some rowdy fish happen to bump into it. It does have a bumper guard to keep fish and the heater safe.

The Fluval Marina heater comes with easy to use brackets and suction cups, so it only takes a few seconds to mount on the interior of your aquarium. This model can only be mounted vertically, but that is not a big deal seeing as it is so small to begin with. When it comes to getting started, the heater itself only needs to be plugged in and it is good to go.

This model has an easy to use temperature setting dial and has a fairly good temperature range too. It is great for most small aquariums, especially tropical ones.

It does come with a light to let you know when it is running. Also, it can be used in both saltwater and freshwater, something which many people will appreciate.


  • Easy to set temperature dial.
  • Easy to install.
  • Fairly durable.
  • Comes with suction cups.
  • Good for fresh and saltwater.
  • Space saver.


  • May not be all that accurate at times.

See more info and pricing at Amazon

4. Hydor Slim Heater for Bettas

This is definitely one of the more unique water heaters for betta tanks out there right now. Unlike traditional heaters which are long and tubular in shape, this one is like a flat oval that sits on the side of the aquarium.

It may not look all that nice, but its shape is convenient because it barely takes up any room at all inside of your betta tank. Even though the Hydor Slim Heater is very small, it is still quite powerful and can easily heat up a tank of 5 gallons.

The element inside of the Hydor Heater is designed to heat up a tank or terrarium to around 10 degrees warmer than room temperature, making it ideal for bettas. That being said, it is a simple plug in and go water heater.

In other words, it has a set temperature that cannot be adjusted. This is something that some people don’t mind, just as long as the required temperature matches the heater’s setting.

What is pretty neat here is that there are no glass components. The exterior is made of a hard rubber which is very durable. The heater won’t break and it won’t hurt your fish either.

Maybe one of the coolest parts here that we liked is that you can hang it on the side of your aquarium or you can out it under the gravel too. The Hydor Heater is definitely a versatile water heating option to consider.


  • No adjustments required.
  • Plug in and go.
  • Can be put under gravel.
  • Very durable.
  • Safe to use.


  • Cannot be adjusted.
  • Looks funny.

See more info and pricing at Amazon

5. Cobalt Aquatics Mini-Therm Heater

Unlike the previous heater which was made of rubber, this one is made of glass. This does make some people worry due to durability issues, but the Cobalt Aquatics Heater is made with a shatter proof design that makes it difficult to break. The internal components will not be exposed to water, your fish won’t get electrocuted, and this little guy is proven to have a long life.

We do also like how this heater is very small and compact. It is round and tubular in shape, just like most other aquarium heaters out there. However, its very small and compact build makes sure that it does not take up too much space inside of your betta tank.

This heater can be used for both freshwater and saltwater aquariums though it cannot be adjusted in terms of the temperature.

It is rated to raise the water temperature to around 10 degrees above room temperature. Simply plug the Cobalt heater in and let it do its job. It really does not get any easier than that.


  • Very easy to use.
  • Space saver.
  • Good for salt and freshwater.
  • Plug in and go.
  • Shatterproof design.


  • Cannot be adjusted for temperature.

See more info and pricing at Amazon

6). FreeSea Aquarium Heater

Here we have a very small aquarium heater, one that is ideal for a 1 to 10 gallon tank, although there are also larger options which will work for tanks up to 50 gallons.

This is a convenient little heater, as it can heat aquariums to anywhere between 59 and 94 Fahrenheit, which should be more than enough.

It’s convenient because it has an automatic temperature function, so it will maintain a constant temperature and turn on whenever the temperature goes below the set point.

Simply plug it in, set the temperature, and place it in the water. It’s 100% submersible and comes with a 1 year warranty. It’s also highly rated for safety, so it shouldn’t fry your fish.


  • Very safe.
  • Simple to use.
  • Wide temperature range.
  • Set and forget.


  • Limited durability.
  • Only use 100% submerged.

See more info and pricing at Amazon

7). Szelam Smart Mini Aquarium Heater

Here we have another nice little aquarium heater, and it comes with some variety, including a 25, 50, and 150 watt model, but the 25 watt model should be enough for a small 5 gallon betta fish tank.

When it comes to 5 gallon heaters, it’s probably one of the best ones out there. It’s a very simple heater, because you just have to stick it to the interior of your tank using the included suction cups.

After you have done that, set the temperature and forget about it. This heater comes with smart tech, so it always measures the water temperature and then adjusts itself accordingly.

It doesn’t have the largest temperature range, but can still go from 73º to 82º, which is enough for a betta tank. It’s a very small and compact heater, so it won’t take up too much space either.


  • Very simple to use.
  • Set and forget.
  • Ideal for small tanks.
  • Takes up little space.
  • Safe.
  • Energy efficient.


  • Limited temperature range.
  • Limited durability.

See more info and pricing at Amazon

Commonly Asked Questions

What is the best betta tank heater?

Personally, we think one of the best options is the Tetra HT Submersible Aquarium Heater. First off, it’s very small and barely takes up room, which is a big deal for a small fish tank.

Next, it’s also very highly rated for safety, which is nice because you obviously don’t want your fish to get fried.

What’s very convenient about this particular heater is that it automatically heats to 78 degrees, which is perfect for betta fish, although you might not like that it is not adjustable.

That said, simply use the suction cups to put in in your aquarium, plug it in, and it will do the rest all on its own.

Can you put a heater in a betta bowl?

Yes, you can put a 5 gallon heater in a 5 gallon betta bowl. Seriously folks, you need to be using a fish tank complete with filtration and lighting for a betta fish, and yes, this includes a heater too.

You should never be using a simple fish bowl for any kind of fish. IN fact, aquarium stores should not be allowed to sell them as it is generally considered to be inhumane.

How do you put a heater in a betta tank correctly?

There are different ways of installing a heater, and it all depends on the specific heater in question.

Most of these little heaters just need to be placed inside of an aquarium using the included suction cups. Make sure to read whether it has to go vertically or horizontally, or if it can handle both positions.

Also, keep in mind that some heaters need to be fully submerged. Other than that, there’s really not much to think about here.

Do I need to do any maintenance to my 5 gallon tank heater?

Aquarium heaters, especially small and inexpensive ones, don’t really need maintenance. Sure, you can clean the exterior every now and again, but in all reality, there is no way for a normal person to maintain these things.

Unless you have a degree in engineering and know how to repair broken aquatic heaters, either it works or it doesn’t.

As far as general fish keeping goes, maintenance is not really a thing in terms of aquarium heaters.


When it comes to finding the right heater for your 5 gallon Betta tank there are plenty of options out their but the above 7 will certainly do the job (the Tetra HT is our top pick) . We hope we have helped you on your Betta heater search!

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