best betta tank heater

The 5 Best Betta Tank Heaters in 2022 (Our Top Choice)

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Do you need a heater for your bettas? Yes, you do. Getting an aquarium heater for your betta fish sounds like a pretty straightforward issue to solve.

Quick Summary: Best Betta Tank Heaters

Fluval M50 Ultra-Slim Submersible Aquarium Heater – 50W Underwater Heater for Aquariums up to 15... Fluval M50 Submersible Heater
  • Easy to install
  • Shock resistant Borosilicate glass
  • 3-year warranty
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Aqueon Aquarium Fish Tank Preset Heater For Up To 40 Gallons, 100 Watts Aqueon Preset Heater
  • Preset to 78°, accurate to +/- 1°
  • Shatter resistant
  • Ideal for aquariums up to 30 gallons
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ViaAqua 50-Watt Quartz Glass Submersible Heater with Built-In Thermostat Hygger Aquarium Double Sponge Filter
  • High quality quartz glass
  • Fully-submersible
  • For use in fresh or saltwater aquariums
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That is until you see how many there are available and all of the various shapes, sizes, and wattages. If you are new to the world of aquarium heaters, we’re here to help!

Narrowing Down Your Options

In the past, heating your aquarium meant purchasing one of only two types of heating devices. Your choices were devices that were one-setting-only, thermostatic submersible types made of glass, or an automatic heater that hung on the back of the aquarium.

Now, the assortment of available heaters can fill entire aisles of stores. You can select from multiple sizes and shapes, temperature outputs, build materials, wattages, control systems, and more.

Fortunately, if you keep this rule of thumb in mind, picking an aquarium heater is easy.

You need 25 watts of power for every 10 degrees of ambient temperature per 10 gallons of water.

For example, say the ambient temperature of your home is 70°F. You have a 10-gallon aquarium that needs to be heated to 78°F. For a single-setting heater, you would need 25 watts of power to get that 8°F difference.

However, you could also use a 50-watt aquarium heater with variable temperature controls. If your home is colder at various times throughout the year, that’s the way to go. That way, you can set that heater on low and have room to increase the temperature if necessary.

The Importance of Wattage

For many people, a fairly large concern is their lack of knowledge and fear of hurting their fish. For the most part, aquarium heater issues arise when the heater being used isn’t the correct wattage for the aquarium it’s being used in.

As long as you stick to the rule of thumb above, you will ensure that you end up with healthy and happy betta fish. Keep in mind that sales representatives may encourage you to get a higher wattage for the sake of making a higher sale. Always make sure to educate yourself before making a purchase.

Best Betta Tank Heaters

ViaAqua 50-Watt Submersible Heater

ViaAqua 50-Watt Quartz Glass Submersible Heater with Built-In Thermostat
  • High quality quartz glass
  • Fully-submersible
  • Visible temperature setting

This is a pre-set heater made of quartz glass, making it break-resistant. We like this one because it’s pretty easy to set up, using suction cups for secure attachment. The temperature setting is visible, and the device is fully submersible.

The minimum 50-watt option might be a bit much for novice hobbyists with smaller tanks. However, the construction and design are good examples of what you should be looking for with this type of heater.


  • High-quality quartz glass
  • Fully-submersible
  • Visible temperature setting


  • Temperature adjustment isn’t very accurate
  • Too hot to touch without gloves

Elite Thermostatic Heater

Elite Thermostatic Heater, 8-Inch/50-Watt
  • 50-watt aquarium heater
  • Maintains accurate aquarium temperature
  • Pilot on/off switch

The Elite Thermostatic is a hang-on-the-back heater. This is a 50-watt product, but this brand does sell a “mini” 25-watt option. It’s not top-of-the-line by any means, but it’s affordable and reliable.

It’s a bit old-school (which isn’t a bad thing) and uses a pilot on/off switch and an adjustable heater gauge to operate.

With this product, it’s important to remember that you must keep the heater element submerged. Take care to submerge the heating element first, let it sit, then slowly heat it up. You don’t want the glass to bust by plunging the already hot heater into cold water.


  • 50-watt aquarium heater
  • Maintains accurate aquarium temperature
  • Pilot on/off switch
  • Suitable for a 10-gallon aquarium


  • Not suitable for a larger tank
  • Too large to fit in a 1-gallon tank

Aqueon Preset Heater

Aqueon Aquarium Fish Tank Preset Heater For Up To 40 Gallons, 100 Watts
  • Preset to 78 degree, accurate to plus/- 1 degree
  • No adjustment required
  • Shatter resistant

This is a resin-covered preset heater. While it’s more durable in terms of drop resistance, it’s not quite as durable as its glass counterparts. However, preset heaters are cheaper, and this one is no exception. This preset heater stays on at 78 degrees.

Essentially, this is a good, cheap placeholder until you can invest in something a little more substantial with a longer warranty (this one is just 1-year).


  • Preset to 78°, accurate to +/- 1°
  • No adjustment is required
  • Shatter resistant


  • Not great for long-term use
  • Short warranty
  • Cheap

AquaTop Digital Heater

AQUATOP 200W Digital Heater with External Control - Fully Submersible for Fish Tanks Up to 50...
  • FULLY SUBMERSIBLE AQUARIUM HEATER: Aquatop's EX Series of fully submersible digital heaters offers a compact design for versatile placement and is extra durable due to the built-in glass element.
  • GREAT FOR FRESH & SALTWATER TANKS: Aquatop’s EX Series is suitable for both freshwater and saltwater aquariums up to 50 gallons. The heater has a range of 68-93 degrees Fahrenheit.
  • SIMPLE TEMPERATURE ADJUSTMENT: The remote external thermostat control of this heater for fish tanks has an LCD display and is simple and easy to adjust the temperature setting without getting your hands wet.

This digital heater is equipped with a dual-temperature display. The temperature sensor is separate from the main device, making it more accurate and allowing for a more stable heat maintenance process.

It is fully submersible and has memory storage, which is great if you frequently experience power outages.


  • Digital Touch Control
  • Temperatures adjustable between 20c-34c/68-93F
  • Heating Indicator Included
  • Suitable for tanks up to 50 Gallons


  • Breaks quickly
  • If bought from Amazon it doesn’t qualify for warranty coverage

Fluval M50 Submersible Heater

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Fluval M50 Ultra-Slim Submersible Aquarium Heater – 50W Underwater Heater for Aquariums up to 15...
  • Modern Aesthetic: M-Series heaters combine modern aesthetics with reliable Italian construction. Employing an ultra-slim profile, these heaters are a welcome departure from traditional, bulkier designs.
  • Reflective Design: This heater is encompassed in a heat-and-shock resistant reflective Borosilicate glass tube, which allows it to reflect the surrounding aquarium colors, allowing it to blend in with the environment and enhance overall aesthetics.
  • Temperature Control: Computer-calibrated thermostat has an easy-to-adjust temperature control dial and an on/off blue indicator light to display when it’s in use.

​This fully submersible heater is a less expensive option. Although this heater has a limited range between 66 and 86 degrees, it should work for your betta. You can easily change the temperature in 1-degree increments.

This heater is easily installed with a mounting bracket anywhere on your tank. It’s also shockproof and suitable for tanks up to 15 gallons. There are also larger options for this same heater up to 200 watts.


  • Fully submersible
  • Suitable for up to 15 gallons
  • Affordable
  • Comes in different sizes up to 200 watts for multiple aquarium sizes


  • Burns out quickly
  • Users report it will get stuck at a specific temperature

Types of Tank Heaters

Preset Heaters

Preset aquarium heaters, also called Thermostatic heaters, are a type of aquarium heater that has an analog thermostat built into the device. Some types of preset heaters have a remote sensor that gauges the aquarium’s temperature separately from the main heating unit.

Nearly every thermostatic heater is fully submersible. These heaters all come with a line that indicates the minimum submersion depth needed for the heater to function. In most cases, you won’t have to fully submerge your heater.

As mentioned earlier, give these heaters a 30-minute pre-soak in the fish tank before plugging them in. This will give the aquarium heating unit time to acclimate its internal components to the existing temperature of the aquarium.

When you plug in the preset heater, it’s best to have a secondary thermometer on hand to verify the temperature. Experience shows that it’s normal for preset heaters to be off by a few degrees right out of the box.

If there’s a gap, keep it in mind when adjusting any settings. Also, note that the gap will likely grow larger over time as you near the time to replace the heater.

When mounting the preset heater to your betta’s aquarium, it’s best to mount it vertically. If you decide to mount it horizontally or diagonally, there is a chance water will breach the seal at the top of the heater and cause failure and damage.

Plastic-Covered or Resin Heaters

Plastic or resin-covered heaters are closely related to glass/quartz preset heaters. Some refer to these heaters simply as “smart” heaters.

They generally have a low-temperature variance and a built-in LED warning system. The warning system generally kicks in when the temperature of the tank is +/- 5°F from the preset temperature.

Hang-on-the-Back Heaters

“Hang on the back” heaters, also known as “Automatic” aquarium heaters, are designed to “hang on the back” of the aquarium you are trying to heat.

Their other common names (e.g., “Automatic”) are a bit misleading as they don’t adjust their power output by sensing the current temperature.

They work using a remedial thermostat. When you make adjustments to the control dial on the heater, you are either tightening or loosening metal contacts on the bi-metal lead.

Essentially, this just means the heater is “on” for a longer or shorter amount of time. This also means you have to watch out for ambient temperature swings and season changes, adjusting accordingly.

If you have one of these types of heaters, it’s crucial that you make sure that the water level is maintained at the required level indicated on the heater.

Failure to maintain the proper water level will end up causing the heater to fail. Failure for these types of heaters means that the heater cracks under the stress of dry heat.

On the plus side, they are very affordable. Also, because they hang on the back of the tank, they will fit almost any aquarium. Many aquarists keep one or two of these heaters as a backup due to their affordability and easy use in virtually any tank

Digital Heaters

These heaters are also closely related to preset heaters. They are almost the exact same except for the fancy digital temperature readout display built in.

Some of the differences between a digital heater and a typical preset heater are:

  • Digital heaters have a dry detection auto-shutoff
  • Digital heaters have higher accuracy in temperature control
  • Digital heaters have a temperature display
  • Digital heaters have 2x insulation around the heating element

Under-Gravel Heaters

Under-Gravel Heaters are very popular with new betta owners. These “under the gravel” tank heaters are made specifically with small-capacity aquariums in mind. These mini heaters are rated to heat up to 5 gallons but are intended for a 1-2.5-gallon tank.

Under-Gravel heaters work on an internal “automatic” setting that adjusts the temperature of the aquarium based on a hard-set internal temperature limit.

Each device has its own temperature standards and variances, but most will increase the temperature of an aquarium within 5 degrees of the ambient temperature.

What tends to attract people to these heaters is that they are invisible, except for their waterproof power cords. They are also always on, making them a “set-and-forget” type of heater.

However, there are a few reasons we haven’t recommended one of these in our buying guide. First, you shouldn’t have your betta in a tank small enough for these to be a valid option for you.

The only tanks these “under the gravel” options are good for are the 1–2-gallon tanks. Your betta should be kept in a 5-gallon tank at a minimum.

Things to Consider When Buying a Heater


When you make your aquarium heating selection, you need to set it up properly to provide good circulation around the heating element.

Aside from safety concerns, providing a good amount of circulation around the aquarium heater will make it much easier to control the temperature. Good water circulation around the heater also makes the readings more accurate.

Bigger Tank Tips

If you have a large aquarium and the temperature of your home is 25°+ degrees colder than you want your aquarium to be, you can install a second heater following the same guidelines.

For larger fish tanks, doubling up on your heaters rather than purchasing one strong heater will allow your aquarium to distribute heat more efficiently.

However, keep in mind that many heaters are specifically designed to only heat up to a certain temperature. If you try and heat above the recommended high-temperature setting, it may result in heater failure.

Extension Cords: Yay or Nay?

The power cords for aquarium heaters are specially designed and manufactured for use with a specific heater. Using an extension cord may not be the wisest idea.

The power drawn from the heater may cause extension cords to heat up, causing the cord’s insulation to fail. Most manufacturers warn against using power strips with your tank heaters as well.


If you begin to see condensation occur after you set up a glass heater, it’s fairly common to have a small amount of condensation gathering on the inside of the heating enclosure.

This isn’t necessarily a sign that your new quartz aquarium heater is leaking and defective. If you notice that the condensation is growing and pooling inside the bottom of the glass enclosure, you may have a problem.

Basic Aquarium Heater Setup

Acclimation and Submersion

When installing a new aquarium heater, you should place the device in the aquarium water for at least a half-hour before plugging it in.

Letting the heater soak in the fish tank while it’s powered down will allow the device to acclimate its internal components to the initial temperature of the aquarium.

With pre-set submersible heaters, submerge the heater to at least the minimum water line.

Aquarium heaters that are the “hang on the back” type should be submersed exactly to the water line indicated on the device. If the water level on these types of heaters is either too high or too low, heater failure can occur.

Heat Adjustments

In general, you shouldn’t adjust the temperature on the heater’s dial-up or down more than 5°F per day with fish in the tank. If the tank is empty, you can make larger adjustments.

When adjusting the temperature control dial on manual models, make adjustments in small quarter-turns. If you can manage, smaller turns are better.

With the pre-set heaters, you should do a few water temperature tests. It’s common to have the real temperature of the tank be off by a few degrees Fahrenheit with pre-set heaters.

Multiple Heaters

If you are one of those people with a lucky betta fish swimming in a large tank and are subsequently using more than one heater, we recommend adjusting one heater at a time.

It can be difficult to set the correct temperature for an individual heater while there is another heater currently running in the tank.

However, if you are running two heaters because you need the combined wattage, you will need to set both at the same time, making micro-adjustments to get the perfect temperature.

Water and Electricity Safety

Make sure to use a drip catch when connecting the heater to a power supply. This isn’t a difficult thing to do and doesn’t cost anything. If the cord is running in a straight line at a downward angle to the outlet, water will enter the outlet.

To stop this from happening, make sure there is enough slack in the heater’s power cord to fall just below the power outlet, and then rise up again to attach to the outlet. Imagine a U-shaped bend in the power cord that falls below the power outlet.

This U-shaped bend in the power cord will be the lowest point where the water can travel down the cord. As water can’t travel on its own at an upward angle, the U-shape will keep any water traveling down the power cord from entering the outlet.

Changing Your Water

When it’s time to change out the water in the betta tank, remember to turn off any heater. It’s best not to expose the heating element or the heat sensor to air, as this will shorten the life of the heater.

It’s also a good idea to let the heater sit while turned off and still submerged in water for around 20 minutes before the actual water change. This will give the heater time to cool and let the temperatures of both the water in the tank and the heater equalize.

Our Top Recommendation

Overall, we recommend the Elite Thermostatic heater for your betta tank. It’s great for maintaining the proper temperature for your betta fish and providing quality consistent heat for betta tanks.

Elite Thermostatic Heater, 8-Inch/50-Watt
  • 50-watt aquarium heater
  • Maintains accurate aquarium temperature
  • Pilot on/off switch

Best Tank Heater for a 3 Gallon Tank

Due to a 3-gallon aquarium small size, we recommend the Aqueon Mini-heater. This 7.5-watt model is fully submersible and shatterproof. It can be used with glass or acrylic tanks, has suction cups for easy installation, and warms the water up to six degrees above room temperature.

Aqueon Small Aquarium Fish Tank Submersible Mini Flat Heater Up to 2.5 to 5 Gallon Aquariums, 7.5...
  • Fully submersible
  • Vertical or horizontal placement using suction cups that mount to the bottom or side wall of tank
  • Quick and easy installation

Best Tank Heater for a 5 Gallon Tank

Our top heater pick for your 5-gallon betta tank is the Eheim Jager Thermostat. This heater comes in eight different wattages for multiple tank sizes.

EHEIM Jager Aquarium Thermostat Heater 50W, Black
  • Fully submersible
  • Thermo safey control protects against running dry
  • Will automatically turn off when water level dips too low

The 50-watt heater is ideal for a 5-gallon tank. This heater is fully submersible, has thermo safety control, automatically turns off when the water level is too low, and is shock resistant and shatterproof.

Best Tank Heater for a 10 Gallon Tank

For a 10-gallon tank or larger, our top pick is the Fluval M200 heater. This aquarium heater blends into the aquarium environment with reflective technology, it has a computer-calibrated thermostat, is shock resistant, and is easy to install with a slim profile tube.

Fluval M 200 Watt Submersible Heater
  • Submersible heater provides exceptional performance and unsurpassed reliability
  • The heater also includes an exclusive mirror technology that reflects the colours of the aquarium and enhances overall aesthetics.
  • Sleek and compact


What water temperature do betta fish need?

Betta’s aquarium water should be kept between 75- and 80 degrees Fahrenheit. Colder water can cause bettas to become ill, while water that’s too hot can make them age quickly and increase their metabolism.

How can I heat my tank without a heater?

There are some temporary solutions to keep the tank water warm without a heater, but none of these will work long-term.

Close the Lid

One of the simplest ways to keep the water at the proper temperature is to keep the lid closed. This will keep the water warm for a short period of time.

Use a Strong Light

Another simple way to keep your tank water warm is to use your aquarium lights. Some aquarium lights give off more heat than others.

You can use this to your advantage to keep the tank water warm, but it’s best to monitor the temperature closely.

Keep Your Tank in a Warm Area

Keeping the tank in an area of your home that is warmer than others will help to keep the water warm. Placing the tank with sources of sunlight can also help to warm up the tank water.

Have a Smaller Tank

The larger your tank, the longer it takes to heat up. Therefore, the smaller your tank, the faster it will heat up.

However, the heat will also dissipate quicker, so this isn’t the best option. This can also be tricky to master.

How Do I Make Sure My Heater Is Working Properly?

If your heater isn’t increasing the water temperature, this is a good indication that it isn’t working. When testing a new heater, turn the device off first then turn it on. The water temperature should go up by a few degrees automatically.

Where Should a Heater Be Placed?

The best place for a heater in your tank is near the maximum water flow like the outlet or inlet of the filter. Placing water flow past the heater helps to evenly disperse heat throughout the tank.

Can My Fish Be Burned by a Heater?

It isn’t likely but it is possible. This would only happen if a betta were to get stuck between the tank glass and the heater. Although it’s rare, it’s best to prevent your fish from getting burned by your heater.

Why Is My Fish Hiding Near the Heater?

Betta fish usually hide behind heaters for a few different reasons. If the tank’s temperature is below 75 degrees, the water current is too strong, the water conditions are low, or there is a lack of hiding spots, bettas may hide near or behind the aquarium heater.


Overall, you need to take into consideration a few different factors before choosing an aquarium heater.

  • The size of your tank
  • The fish you keep
  • Outside temperature fluctuations
  • Temperature sensitivity
  • Your budget

In most cases, choosing a typical preset heater for a 10-gallon tank will suit your betta just fine. Taking a look at under-the-gravel heating options would be wise for tanks in the 2.5-gallon range. Don’t forget to adhere to the rule about choosing the correct wattage.

Whatever heater you choose, you’ll need to maintain water temperatures in the 75°F-80°F range. Lastly, consider picking up a Hang-On-The-Back heater. It may come in handy as a backup in case something goes wrong unexpectedly.

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