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Best Heater For Betta Tank Setups: Accurate & Stable Temperature

Betta fish are highly sensitive to temperature changes so it’s key to choose the best heater for betta tanks.

By Matt Thomas
Last updated on

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best heater for betta tank

Bettas are tropical fish originating from warm water areas of Southeast Asia. They can be very sensitive to temperature fluctuations in your aquarium, so it’s important to find the best heater for betta tanks.

We’ve used many heater types for our betta tanks over the years. And we spent many hours assessing some of today’s top heaters to help you make the right choice. 

Overall we chose the Freesea 50W Mini Heater as the best for 5 gallon betta tanks due to its compact size and ability to hold a stable temperature.

But we’ve also reviewed betta heaters for larger tanks, precision digital heaters, and affordable budget options. So take a look below to find the right one for your betta!

  1. Best Compact Betta Heater: Freesea 50W Mini Heater
  2. Best For 10 Gallon Betta Tank: Fluval M50 Submersible Heater
  3. Best Budget Heater: HITOP 25W/ 50W Adjustable Heater
  4. Best Premium Digital: Cobalt Aquatics 25W/ 50W Neo-Therm
  5. Best Budget Preset: Tetra HT10 Submersible Heater

Best Heater For Betta Tank Setups Reviewed

All of the heaters in this list can hold a steady temperature for your betta fish. But we’ve also reviewed them against criteria including accuracy of adjustment, ease of use, and safety features such as auto shut-offs.

1. Freesea 50W Mini Heater


  • Heater Type: Submersible, adjustable
  • Dimensions: 3.7 (l) x 1.5 (d) x 2.5 (w) inches
  • Wattage: 50 Watt (75 Watt & 100 Watt also available)
  • Key Features: Temperature range of 59 to 94°F, LED temperature display, touch-operated adjustment switch on cable, built-in thermostat
  • Best For: Compact Betta Heater

Freesea’s 50W Submersible Mini heater is one of the best heaters for betta tank setups if you need one that’s ultra-compact. At just 3.7 (l) x 1.5 (d) x 2.5 (w) inches it’s great for small, unusually shaped tanks. So is perfect if you have a small bowfront, or even a spherical tank.

At 50 Watts, although you can use it in a 10 gallon betta tank, we prefer to use it in a 5 gallon aquarium. The extra power means it will easily handle changes in your room temperature during the winter, so you can be confident your tank’s temperature will stay stable for your betta.

It’s adjustable from 59 to 94°F, so you can set the optimal temperature for your betta at around 79°F. And we found the built-in thermostat maintained a consistent temperature. But there’s no automatic switch-off it runs out of the water. So always ensure it is kept fully submerged.

The LED temperature display is easy to read, even from across the room. And as the touch-operated controller is mounted on the cable, you can change the temperature without getting your hands wet!

Some owners have reported there is space between the suction cup mount and the heater where their betta might get trapped. Although there are few cases of this actually happening, we recommend using some filter sponge around the suction cups for peace of mind.

  • Ultra compact for smaller betta tanks
  • Accurate thermostat and stable temperature
  • Easy-to-use control located on cable
  • Fitted bumper guard
  • Space between suction cups could trap long fins

2. Fluval M50 Submersible Heater


  • Heater Type: Submersible, adjustable
  • Dimensions: 11.0 (length) x 1.0 (diameter) inches
  • Wattage: 50 Watt (other wattages available)
  • Key Features: Temperature range of 66 to 86°F, shock-resistant glass heating tube, computer-calibrated thermostat, ceramic heat sink, heating indicator light
  • Best For: 10 Gallon Betta Tank

If you have a 10 gallon tank for your betta, the Fluval M50 Submersible Heater is a fantastic choice. It has a ceramic heat sink running the length of the tube which helps warm your tank evenly. This will prevent your betta from being stressed by any temperature fluctuations.

At 11.0 inches long it will fit a standard 12 inch high 10 gallon tank if positioned at an angle, and is also a good fit for tall, narrow tanks. But if your aquarium is shallow do check your measurements first. The M50 is also ultra-slim, so won’t obstruct your betta or plants.

The large adjustment dial is located at the top of the heater and marked in 3-degree increments. So you can easily adjust it to an accurate temperature. And because the M50 adjusts from 66 to 86°F, it’s mid-range is perfect for your betta at around 79°F.

There’s a simple indicator light showing when the M50 is actively heating, so you can easily see if there are any faults. And the tube is made from shock-resistant borosilicate glass. This means there’s less danger of damaging the tube during installation or maintenance.

Note this heater doesn’t have an overheat or auto shut-off. So make sure you keep it submerged at all times to avoid damage. But overall many owners praise the M50 for it’s reliability and ease of use.

  • Mid point of temperature range (79°F) perfect for betta
  • Ceramic heat sink helps maintain stable temperature
  • Large adjustment switch with easy-to-read dial
  • Shock-resistant glass
  • No overheat or run-dry auto shut-off
  • Many be too long for shallower 10 gallon tanks

3. HITOP 25W/ 50W Adjustable Heater


  • Heater Type: Submersible, adjustable
  • Dimensions: 25/ 50 Watt = 7.2 inches (length)
  • Wattage: 25/ 50 Watt (other wattages available)
  • Key Features: Temperature range of 68 to 93°F, 2mm thickened quartz glass, built-in thermostat accurate to +/- 2°F, LED heating indicator, stick-on thermometer included
  • Best For: Budget Heater

HITOP’s submersible heater is a great option if you want an adjustable aquarium heater at an affordable price. It can be set anywhere between 68 and 93°F, and it’s thermostat is accurate to +/- 2°F. So it will comfortably maintain a stable 78/ 79°F for your betta.

It has multiple heating wires running along the tube to help heat your water evenly. So you’ll avoid temperature fluctuations which can harm your betta. But note some owners report it can run 1 or 2°F too high, so use a separate in-tank thermometer to check.

At 7.2 inches long, both the 25 and 50 Watt models are very compact for a glass submersible heater. So you have the flexibility of choosing either model for your 5 gallon betta tank based on your climate, while knowing that either will fit.

The large control knob on top of the heater is easy to access and turn. But its +/- dial has no temperature markings making it tricky to set an accurate temperature. So do use it with an in-tank thermometer or the stick-on thermometer provided.

Overall though many users remark that the HITOP is a great option for maintaining a consistent temperature for your betta if you are looking for an adjustable budget heater.

  • Multiple heating wires for consistent, even heating
  • Easy to turn control knob located on top
  • Compact – will fit 5 gallon betta tanks
  • 2mm shockproof thickened glass
  • May run 1 or 2°F higher than set temperature
  • +/- temperature dial has no numerical breakdown

4. Cobalt Aquatics 25W/ 50W Neo-Therm


  • Heater Type: Submersible, adjustable, digital
  • Dimensions: 25/ 50 Watt = 6.75 (length) x 2.25 (width) x 1.25 (depth) inches
  • Wattage: 25/ 50 Watt (other wattages available)
  • Key Features: Temperature range of 68 to 94°F, shatterproof casing, built-in thermostat accurate to +/- 0.5°F, touch-button control, LED set and current temperature, overheating shut-off
  • Best For: Premium Digital

With a built-in thermostat accurate to +/- 0.5°F, the Cobalt Aquatics Neo-Therm is one of the most precise heaters we’ve assessed. In fact, it’s one of the best heaters for betta tanks if you want to be assured of maintaining a steady 78°F for your betta.

It has a simple touch-button control allowing you to set it in 2°F increments. We would have preferred 1°F adjustment, but you still have the ability to set 78 or 80°F making it very close to the optimal temperature for your betta of 79.8°F.

Clear LEDs show the current water temperature along with the set temperature. So it’s really easy to see if you need to make any adjustment. And there’s an auto shut-off if the temperature gets too high, meaning you can be confident you won’t overheat your betta.

The Neo-Therm is also incredibly compact, with the 25 and 50 Watt models only 6.75 inches long and 0.47 inches at their thinnest point! So although the 25 Watt model is perfect for tanks up to 6 gallons, either will fit and can be easily disguised by plants.

While this digital heater is quite expensive it gains great feedback from users for it’s reliability and precise heating. And the shatterproof casing along with the 3-year warranty gives extra peace of mind that it will last for years.

  • Stable heating accurate to +/- 0.5°F
  • Compact and ultra-slim
  • Current and set temperature LED display
  • Overheat auto shut-off
  • Tough shatterproof casing
  • Premium price
  • Can only change temperature in 2°F increments

5. Tetra HT10 Submersible Heater


  • Heater Type: Submersible, preset
  • Dimensions: 5.25 (length) x 1.6 (diameter) inches
  • Wattage: 50 Watt (other wattages available)
  • Key Features: Preset temperature of 78°F, heating indicator light, built-in electronic thermostat
  • Best For: Budget Preset

Tetra’s HT10 preset submersible heater is the simplest and lowest priced option on our list. As it’s a preset heater you just place it in your water and it will maintain a set 78°F. So although adjustable heaters give you more flexibility, this preset gives a perfect temperature for bettas.

Designed for 2 to 10 gallon tanks, we found it maintains a steady temperature in a 5 gallon betta tank but can struggle in a 10 gallon tank. So if you live in a colder area and have a 10 gallon aquarium or above we’d recommend the 100 Watt version.

It has a clear LED light which shows red when actively heating and green when the 78°F temperature has been reached. So if you keep a separate thermometer in your tank you can easily see if there are any faults.

The HT10 is really compact too at 5.25 x 1.6 inches, so will fit your 5 gallon betta tank with ease. You can also mount it horizontally or vertically for a better fit and easily conceal it behind plants or decorations.

Although some owners report the HT10 can be 1 to 2°F out from the set temperature, the majority praise this heater for its ability to maintain a stable temperature, its ease of use, and its affordable price.

  • Affordable
  • 78°F preset temperature in range for bettas
  • Simple to use and maintains temperature
  • Compact
  • Only one suction cup for mounting
  • Some report it can be out by 1 to 2°F

Considerations Before Buying The Best Heater For Betta Tank Setups

When looking for the best heater for betta tank setups there are several things to think about before you start.

pink betta fish in aquarium

What Temperature Do Betta Fish Need?

Bettas originate from areas of tropical water in countries including Thailand. The temperature of their habitats, such as shallow streams and rice paddies, can range from 75°F to as high as 88°F during the breeding season [1].

In your aquarium, your betta will do best at around 75°F to 81°F. Go below this and your fish can become lethargic and more susceptible to disease. Any higher and its metabolism will increase, which can lead to a shorter lifespan.

It’s also key to maintain a consistent temperature. Constant fluctuation, even within this range, can stress your betta. Research has shown the optimum temperature for betta’s during breeding is around 79.8°F [2]. And it’s thought this is best for their general well-being too [3].

Why Do You Need The Best Heater For Your Betta Tank?

Unlike the large areas of water in the wild, your betta tank is heavily influenced by changes in your room temperature. While room temperature is commonly around 68 to 72°F [4] it can differ based on your location, climate, the seasons, and the time of day.

So using the best heater for your betta tank not only allows you to raise it to the right temperature, but critically it will allow you to maintain a stable temperature and prevent any fluctuations.

What Type Is The Best Heater For Betta Tank Setups?

Single betta fish are often kept in a smaller 5 gallon fish tank, or with a small community of nano fish in a 10 gallon aquarium. 

Submersible heaters are the best heater for betta tank setups like this. Not only do they tend to be more affordable, but because they are fully submerged they are very efficient at maintaining a constant temperature for your betta.

Look for adjustable submersible heaters if you want full control over your betta’s temperature. If you decide to choose a preset heater, which is set at a fixed temperature, make sure it’s close to the optimal temperature for your betta – around 79°F.

Heater Types Unsuitable For Your Betta Fish

As well as submersibles, there are other types of heaters you may come across. However, none of these is the best heater for betta tanks. We’ve outlined the reasons below:

  • External Heaters: Inline, in-sump, and in-filter heaters all sit outside the main aquarium and heat the water externally before returning it. However, they are all designed as large aquarium heaters and are not appropriate for a small betta tank.
  • Substrate Heater: This consists of a heating wire fixed to your tank below the substrate. They only provide enough heat to warm the substrate and are used in planted aquariums to help encourage plant growth.
  • Immersible Heater: Also known as hanging heaters, these sometimes come as part of fish tank starter kits. As they hang off the back of your tank and are not fully submerged they are less efficient than submersibles.

How To Choose The Best Heater For Betta Tank Setups

Take a look at the additional factors to consider to help you choose the best heater for your betta tank.

red half moon betta fish

Wattage Vs Tank Size

The power your heater needs, measured in Watts (W), is mainly based on the size of your betta tank. But it can also be affected by your room temperature and climate.

Based on an ambient room temperature of 68 to 72°F, the general rule is that 2.5 to 5 Watts are needed to heat 1 gallon of water [5], but it’s best to use the higher end of this scale. So the best heater for betta tanks of 5 gallons would be 25 Watts, or 50 Watts for 10 gallon tanks.

This is also based on maintaining a temperature in your tank of around 75 to 80°F. So if you want to heat your 5 gallon betta tank closer to 79.8°F, a 50 Watt heater is entirely appropriate if you live in a cooler climate.

Heater Size And Placement

It’s important your heater physically fits your aquarium. Some 5 gallon fish tanks for bettas can be tall and thin, around 12.0 x 12, x 17.0 inches. Others can be long and narrow, at around 20.0 x 8.0 x 12.0 inches.

Many aquariums of this size have hidden filter compartments also designed to house your heater. So check your tank’s measurements and make sure it will fit. Some of the best heaters for betta tanks are ultra-compact at about 4.0 x 1.5 x 2.5 inches.

Place your heater near your filter’s output and make sure there are no decorations or plants blocking the circulation. This is particularly important if your tank is long and narrow, as placing it by your filter will circulate heated water evenly through your tank.

Adjustability, Readability, And Reliability

If you’re new to keeping betta fish, or on a budget, a submersible preset heater can be a good choice as they are easy to set up with no calibration needed. And many are set in the right range for your betta, often at around 78 or 79°F.

But for full control, an adjustable heater will allow you to set an exact temperature for your betta fish. Some analog submersibles enable you to calibrate to adjust for the current temperature. And some digital aquarium heaters allow adjustment to +/- 0.5°F.

Safety Features

Some of the best heaters for betta tanks have LED or LCD screens showing the current and set temperature so you can see when they are heating your water. But while these aren’t essential, make sure there’s an indicator light at a minimum.

With their long flowing fins, betta fish can often swim against their heater causing them harm. So a bumper guard surrounding the heating element is a very useful safety feature. If your chosen heater doesn’t come with one you can often buy them separately.

The best heater for betta tank setups will also come with auto shut-off features to cut the heater’s power if it runs dry out of the water, or if it is in danger of overheating. Not all submersible heaters have run-dry sensors, so do keep them submerged at all times.

Our Verdict

Whether you have a smaller 5 gallon aquarium or a slightly larger community tank, bettas are very sensitive fish that need a stable temperature of around 79°F.

We chose the Freesea 50W Mini Heater as the best heater for betta tanks of 5 gallons for its compact size and stable temperature. Or if you have a 10 gallon aquarium the Fluval M50 Submersible Heater is our top choice.

But all the heaters on our list can keep a consistent temperature for your betta. So whether you want an adjustable, preset, or digital heater our guide should help you make the right choice for you and your betta!


We’ve answered some of the top frequently asked questions when it comes to choosing the best heater for betta tank setups. Just take a look below!

What Is The Best Heater For Betta Tank Setups?

Submersibles such as the Freesea 50W Mini Heater are the best heater for betta tank setups, as they are very accurate at maintaining your tank’s temperature and detecting fluctuations.

What Size Heater Do I Need For A 5 Gallon Betta Tank?

A 25 to 50 Watt is the best heater for betta tanks of 5 gallons. Make sure you check your measurements and choose a compact heater that will fit your tank too!

What Is The Best Temperature For Betta Fish?

Betta fish will do well in an aquarium between 75°F to 81°F. But the key is to maintain a steady temperature rather than fluctuate in this range. A betta’s optimum temperature is around 79.8°F.

Why Does My Betta Fish Stay Near The Heater?

If your betta hides behind the heater it’s usually a sign your water is too cold so check it’s above 75°F. Or it could be avoiding high water flow, so check your betta’s filter and reduce it if needed.

Photo of author
Matt Thomas
Matt has been keeping fish since junior high when he used to look after his parent's tank. He loves guppies, cichlids, and his crowntail betta named Bobby.

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