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Best Betta Tank Heater For 1, 5 and 10+ Gallon Tanks

Next to selecting your aquarium, the most important part of setting up a betta tank is choosing your heater. Like most tropical fish, bettas require warm and consistent water temperatures to stay healthy and thrive. Choosing the best betta heater for your tank, whether it’s 5-gallon or bigger, is a critical part of the process.

Some aquarium kits come with a heater, but most of the time aquarists have to add one to their set-ups. With so many options, how do you pick the best type of heater for your betta fish tank?

Quick Comparisons of the 5 Best Betta Heaters

tnk-table__imageCobalt Aquatics Flat Neo-Therm Heater
  • Type of Heater: Submersible
  • Thermostat: Yes, integrated
  • Power: 25 & 50 Watt Versions
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tnk-table__imageTetra HT 50-Watt Submersible Heater
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 50 Watts
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tnk-table__imageHygger Fast-Heating Submersible 300-Watt Heater
  • Type of Heater: Submersible
  • Thermostat: Integrated into an external controller
  • Power: 300 Watts
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tnk-table__imageFluval Marina Submersible Mini Heater
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 25 Watt
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tnk-table__imageHygger Mini Submersible 50-Watt Heater
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 50 Watts
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Quick Guide to Betta Heaters

You need an aquarium heater for your betta set-up because they prefer warm aquarium water. The ideal range for bettas is about 75°F to 86°F. It’s unlikely that your tank will stay in this range naturally without using supplemental heat.

Bettas also do not do well if their water temperature fluctuates more than a degree or two. Frequent changes in temperature may cause your betta to feel stressed and get sick. The most common reason for a betta to lose color or stop eating is a tank that’s too cold or one that shifts temperature too much.

Monitoring Your Tank’s Temperature

Hygger Mini Submersible Aquarium Heater temperature control guide.

A good heater with a built-in thermostat will keep your tank at the set temperature automatically. You can monitor the temperature using a thermometer sticker on the glass side, or by using an in-tank thermometer. Your temperature may vary to within a few degrees depending on the placement of your thermometer and heater.

Do you still need a heater and temperature gauge for a betta fish bowl? Yes! If you can’t find a heater that will fit in your tank, chances are it’s too small for your fish. Upgrade to at least a 5-gallon set-up with a heater and thermometer, and your betta will probably be a lot happier.

Types of Aquarium Heaters

There’s actually a wide variety of heaters on the market for aquariums and terrariums. The majority of these styles are not suitable for small fish tanks or betta bowls. Briefly, the types of heaters you’ll find as you shop include:

Style of Heater How it Works Best Heater For
Immersible and Submersible Heaters Sits partially or fully immersed in the aquarium. When the water temperature drops below the desired setting, the thermostat turns the heater on until the temperature is raised sufficiently Aquariums of all sizes
Sump Heater Fits inside the filtration system and heats the water as it flows into the tank or pond Large aquariums (100+ gallons) or ponds with extensive filtration systems.
Undergravel Heater Heating cable is sandwiched between layers of aquarium substrate and heat is concentrated in the lower part of the aquarium Not a popular method in aquariums since the mid 1990s. Used primary in large aquariums (over 50-gallons) with emphasis on maintaining live plants rather than fish
Under-Tank Heat Matt Heating pad sits underneath the aquarium and heats the bottom of the tank Glass terrariums and reptile tanks

Choosing Between Immersible and Submersible Heaters

The best styles of heaters for tanks under 50-gallons and smaller fish bowls are the immersible and submersible types. Both styles usually have a glass tube containing a heating element and thermostat that goes inside your aquarium.

When the thermostat turns on, the element inside gets hot and heats the water around the glass tube. You adjust the thermometer setting via a dial or control knob.

The main difference between these styles is that an immersible heater is not completely waterproof. Instead, the control mechanism sits outside the water and the heater attaches to the top edge of your tank, similar to a HOB filter. Submersible heaters are totally waterproof and sit completely under the water in your aquarium.

Heater Adjustability

Immersible and submersible heaters can be set by moving their control dial or knob and selecting your desired temperature. Depending on the conditions in and around your tank, you may have to make further adjustments. In the summertime, for instance, I have to turn my aquarium heaters up a little to compensate for my A/C.

Hygger 500W 300W Aquarium Heater installation guide.

Immersible heaters can be easier to adjust because their control dials sit out of the aquarium water. In contrast, you may have to reach into your tank to adjust your submersible heater. But submersible heaters are usually higher quality and last longer. They’re typically more expensive too.

Pick The Right Wattage for Your Tank Size

Heaters are ranked by how much power they draw per hour, in watts. The right heater for your tank will depend on how much water it holds and how much you need to increase the water temperature. If your home is on the warmer side year-round, you can get by with a heater that draws less power and has a lower wattage.

If you need to raise your aquarium more than 10 degrees above room temperature, however, you’ll likely need a heater with more power. You can go with the next size up but will have to monitor your tank’s temperature during the warmer months. Otherwise, it could overheat your tank.

I don’t recommend using tanks under 5-gallons for bettas, and heaters under 25-watts are often unreliable. Here are some guidelines to follow when selecting a heater for your tank:

Aquarium Size (gallons) Raising Water ~10°F Raising Water More Than 10°F
Fish bowls and tanks

2.5 and under

(not recommended for bettas)

5 to 7.5 Watts

May not be reliable

7.5 to 10 Watts

May not be reliable

5 15 to 25 Watts 50 Watts
10 50 Watts 100 Watts
20 to 25 100 to 150 Watts 150-200 Watts

Aquarium Heater Safety

Heaters can be a safety risk, so you should always use care when handling or using them. I nearly started a house fire when the water in a plastic container evaporated below the heater’s glass tube. The heater was plugged in, so when the thermostat turned it on the glass shattered and started melting the plastic container.

If you have to remove your heater from your tank, always unplug it and allow it to cool down first. Keep your heater anchored to your tank properly so it won’t shift around. The glass tube is fragile and can easily be broken or cracked if it smacks against the side of your tank or runs into your decor.

pull the plug concept with man pulling black cord and plug. Close up

If your heater’s glass tube breaks or shatters while inside your tank, immediately unplug the heater! Don’t reach inside the tank while the damaged heater is plugged in, or you could be electrocuted. This is a rare event. I’ve only had this problem once in 35 years of fish keeping. Heaters are usually safe if used as directed.

Top 5 Betta Heater Reviews

Let’s take a look at a selection of popular aquarium heaters and compare their ideal tank sizes and temperature ranges. While premium heaters may cost up to twice as much as the less-expensive versions, they are usually more reliable, durable, and long-lasting.

I have several high-quality submersible heaters in my collection that are more than 25-years old and still work perfectly. So you can think of a heater as a long-term investment. If you opt for a cheap heater, it may not be as reliable and you may have to replace it more frequently. For a small betta tank heater, this may not be a problem.

1. Cobalt Aquatics Flat Neo-Therm Heater

Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat (Fully-Submersible, Shatterproof Design) from 25W to 300W
  • Type of Heater: Submersible
  • Thermostat: Yes, integrated
  • Power: 25 & 50 Watt Versions
  • Temperature Range: Adjustable from 66°F to 96°F
  • Size: 3.2 x 2.2 x 7.8 inches
  • Ideal Tank Size: 25W: 5-gallon; 50W: 10-gallon
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If you want to avoid the more delicate aquarium heaters, then this “shatterproof” design from Cobalt Aquatics could be the one for you. Instead of glass, the heater’s tube is made from a durable thermoplastic resin. This heater can take a hit and keep on working! I think this is the best water heater for betta fish in this review.

The submersible Cobalt has an integrated thermostat with an adjustable temperature range, offering a lot of flexibility in its use. The heater comes with a holster you suction to the side of your tank. The flat heater is only a little over 2-inches thick and you can change its orientation in the holster to make the display easier to read.

The Cobalt comes in a wide variety of sizes suitable for tanks of all sizes. The 25 and 50-watt models are ideal for 5 and 10-gallon betta tanks. It’s easy to set with the touch of a button, and will automatically shut down if the temperature goes over 96°F. The display indicates both your set temperature and the actual temp in your tank.


  • Thermoplastic housing is shatterproof and won’t crack or break like glass heaters can.
  • Easy to adjust setting inside your tank with the one-touch control button.
  • Display shows both the set temperature on the heater and actual temperature inside the tank.


  • Flat design is not much narrower than a standard glass heater and doesn’t really save much space in the tank.
  • Expensive, premium-priced heater may be over budget for some users.
  • Heater doesn’t seem to be as long-lasting as traditional designs and may need replacing after a couple of years of continuous use.

2. Tetra HT 50-Watt Submersible Heater

Tetra HT Submersible Aquarium Heater With Electronic Thermostat
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 50 Watts
  • Temperature Range: 78°F
  • Size: 5.2 x 1.6 x 3.5 inches
  • Ideal Tank Size: 10-gallon
Check The Price


If you’re looking for a bargain, then you probably can’t find a better option than the Tetra HT 50-watt submersible heater with an integrated electronic thermostat. This little heater has a durable cap to protect the glass tube from damage. It’s the ideal size for a 10-gallon betta aquarium.

The Tetra keeps things simple, and I think that’s its most remarkable feature. Instead of having to fumble underwater to adjust the temperature, the Tetra’s thermostat automatically heats your tank to 78°F. The red light tells you when it’s heating, and the green light comes on when it stops.

If you need a lot of flexibility in a heater, this one might not be for you. But if you just need a reliable betta tank heater with a thermostat, this is an excellent option. I keep an older version of this heater on hand for emergencies, and it’s never let me down. It may not be as fully-featured as other heaters, but at the price it’s hard to beat!


  • Inexpensive submersible heater with a thermostat that should fit into most betta keeper’s budgets.
  • Red and green lights tell you when the heater is on and when your tank has reached the set temperature.
  • Integrated thermostat automatically heats your tank to 78°F, so you don’t have to adjust its settings.


  • Temperature is not adjustable, so if you prefer a temperature other than 78°F this heater won’t work.
  • May not work well for tanks located in colder areas, since the heat-level can’t be increased.
  • May be too powerful for smaller tanks and betta bowls.

3. Hygger Fast-Heating Submersible 300-Watt Heater

Hygger 500W 300W Aquarium Heater, Fast Heating Submersible Thermostat for Fish Tank 30-120 Gallon, with External LED Digital Display Temp Controller and Thermometer
  • Type of Heater: Submersible
  • Thermostat: Integrated into an external controller
  • Power: 300 Watts
  • Temperature Range: 61°F to 90°F
  • Size: Heater Rod 7.5 inches long
  • Ideal Tank Size: 30 to 60-gallon
Check The Price


While most betta tanks are 10-gallons or smaller, you can certainly keep a male or group of female bettas in a bigger tank. This Hygger fast-heating submersible 300-watt heater is ideal for tanks from 30 to 60-gallons and is packed full of useful features.

The Hygger 300 is a more complex set-up than the other single-piece heaters on my list. The glass heating rod sits in a protected thermoplastic case that attaches to the side of your aquarium. It connects into the external control panel, where the digital display is easy to read and adjust.

The digital display and external control panel is what really makes the Hygger stand out from the other heaters on the list. Since it’s not underwater, the display is very easy to monitor and adjust. The wide temperature range and overall design offer a lot of flexibility for setting up larger betta and community fish tanks.


  • Largest heater on the list and suitable for tanks from 30 to 60-gallons (500-watt model also available for tanks 60 to 120-gallons).
  • Quickly and rapidly heats aquarium water to set temperature.
  • External display panel is easy to see and you can adjust it with the push of a button.


  • More complicated to set-up and operate than the single-piece heaters and requires all three parts to work (heating rod, control panel, and electrical cord).
  • Not suitable for smaller tanks under 30-gallons or betta bowls.
  • Premium price tag may be too expensive for some fish keepers.

4. Fluval Marina Submersible Mini Heater

Fluval Marina Submersible Heater for Aquarium, Mini
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 25 Watt
  • Temperature Range: Varies
  • Size: Heater Rod 6-inches long
  • Ideal Tank Size: 5.5-gallon tanks and bowls
Check The Price


If you need a small betta tank heater, consider this mini option from Fluval. It’s the ideal size for small 5-gallon aquariums and straight-sided fish bowls. The Fluval isn’t fancy or full of features, but it’s a reliable little heater and incredibly inexpensive. It would make an excellent choice for a breeding or quarantine tank too.

The Fluval Marina is an old-school glass tube heater that’s been on the market for years. The integrated thermostat does the hard work of turning the heater on and off for you. You adjust the temperature by turning the control dial up or down. It couldn’t be simpler to use!

The Fluval may be a bit trickier to set than other designs because the dial is underwater, and the display doesn’t show a list of temperatures. You have to turn it on first and see how warm your aquarium gets, and then adjust the temp up or down from there. Still, this is an excellent option for small tanks or larger betta bowls.


  • Inexpensive, old-school design is a reliable classic.
  • Has an integrated thermostat and protective cap on the glass heating tube.
  • Small 6-inch long heating rod should fit inside most 5-gallon tanks and fish bowls.


  • Temperature dial is not marked, so you’ll have to allow the heater to come to temperature before you can adjust it up or down.
  • Temperature dial is underwater when in use, so you have to reach into the aquarium to adjust.
  • Limited use and flexibility, since its maximum tank size is 5.5-gallons.

5. Hygger Mini Submersible 50-Watt Heater

Hygger Mini Submersible Aquarium Heater 50W 100W Adjustable LED Digital Temperature Display Small Tank Heater for Turtle Betta Fish Water Heater with Protective Guard
  • Type of Heater: Submersible
  • Thermostat: Integrated
  • Power: 50 Watts
  • Temperature Range: 63°F to 94°F
  • Size: 2.7 x 1.4 x 4.5 inches
  • Ideal Tank Size: up to 6-gallon
Check The Price


What do you do if your tank is curved so you can’t attach anything to its side, or if you need a heater for a betta fish bowl? One option is this fascinating little mini heater from Hygger. Instead of using a long glass heating rod, this heater is flat and encased in a thermoplastic housing.

The Hygger Mini sits on the bottom of your tank or hangs in a discrete corner if you prefer. It’s nearly indestructible design is durable and protects your fish from harm. The external control panel makes it easy to adjust without having to get your hands wet, too!

The Mini’s heating unit has an LED display that shows the current water temperature and has a light to indicate when the heater is turned on. The integrated thermostat takes care of the hard work, so you can sit back and enjoy watching your betta play. This is an ideal option for awkwardly-shaped tanks and bowls under 6-gallons in size.


  • Shatterproof flat housing renders heater nearly indestructible.
  • External control panel and 1-touch button make it very easy to set and adjust.
  • Does not need to be anchored to the side of a tank, so ideal for curved tanks and betta bowls.


  • Pricier than the other options for small tanks and betta bowls.
  • May be too powerful and overheat tanks under 5-gallons in size.
  • To lower the temperature setting, you have to reset the control panel and adjust the temperature upward to your desired number.


Hygger Mini Submersible Aquarium Heater inside aquarium.

There’s a lot of options when you’re looking at heaters for your betta fish. While you can always opt for an aquarium kit (buy a betta fish tank with heater), adding a heater is not usually an expensive proposition. It’s definitely worth it to invest in a betta tank heater with a thermostat if you have that option in your price range.

The good news is that most designs these days include a thermostat, even in budget or economy heaters. Choosing between aquarium heaters will likely come down to your price range and the list of features you need for your tank. Even heaters for betta fish bowls come with premium features these days!

Hopefully, you’ve found a couple of options suitable for your tank on my list, and we’d love to hear which heater you choose in the comments! If you still need some help deciding, consider these factors:

  • If you’re looking for a premium heater that’s shatterproof and comes in a wide variety of sizes, my Best High-End pick, the Cobalt Aquatics, is an excellent choice.
  • For aquariums larger than 30-gallons, look at the Best Option for Larger Tanks, the Hygger 300.
  • If you need a heater for a small tank or betta bowl, consider:
    • Fluval Marina for 5-gallon tanks.
    • Hygger Mini for bowls and tanks 6-gallon and under.
  • For fish keepers on a tight budget, the Tetra HT gets the job done and is a long-lasting and reliable workhorse.

Jen has more than 30 years experience as a biologist, aquarist, and fishkeeper. She is an expert in setting up new tanks and maintaining naturally-planted freshwater habitats, and has experience raising a wide variety of aquatic species.

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