What Is the Best Heater for 20 Gallon Betta Tank?

Last Updated on August 9, 2022

When it comes to keeping your betta fish healthy and comfortable, there is no question about it: a good heater is essential! What is the best heater for a 20-gallon betta tank you should buy?

Well, that depends on a few factors, including the wattage, tank size, type of heating element used, price, the number of aquarium fish you have, and your own needs and preference.

Your betta fish love it when their water temperature is warm that’s why they need a fish tank heater to keep them warm in the winter and cool in the summer. There are a lot of options out there for aquarium heaters, so it can be hard to decide what is the best one for your tank.

To help you get started, here are 10 of the best 20-gallon fish tank heaters you and your pet will surely love!

Prices pulled from the Amazon Product Advertising API on:

1. Orlushy Submersible Aquarium Heater

Orlushy Submersible Aquarium Heater,100W Adjustable Fish Tahk Heater with 2 Suction Cups Free Thermometer Suitable for Marine Saltwater and Freshwater

The Orlushy Submersible Aquarium Heater comes with a 6ft cord that is very suitable in different tank sizes, including the 20-gallon tank.

It includes an adjustable temperature dial ranging from 68 to 89°F, giving you complete control to set temperature depending on your aquatic climate. Once the set temperature is reached, the Orlushy submersible heater will automatically shut off as the reliable thermostat maintains the temperature.

Moreover, the heater tube is contained in a 2mm thick quartz glass, making it safe to use for both freshwater and saltwater aquariums.


  • Comes with an extra thermometer to check the accuracy of the water temperature
  • Long power cord
  • Can be easily hidden in the tank given its small size
  • Comes in different sizes and heater wattage
  • Fully submerged


  • Glass heaters may tend to shatter
  • Short lifespan

2. Mylivell Aquarium Heater

Mylivell Aquarium Heater Submersible Auto Thermostat Heater, Fish Tank Water Heater and Adjustable Temperature with Suction Cup-100W

Are you looking for a good aquarium heater with an easy-to-read display? You may want to check Mylivell Aquarium Heater out for that.

This fully submersible heater has a temperature range of 65°F-93°F, both suited for saltwater and freshwater tanks, that will surely provide your tropical fish with a warm environment. With its heating component hidden in shatterproof glass, you can rest assured that your fish will be safe.

Just mount the suction cups to your tank, set your temperature settings, and let this aquarium heater do its job!


  • Polarized plug to prevent electric shock
  • Affordable
  • Strong suction power


  • Temperature knob can be stiff at times
  • Durability issue

3. Uniclife Aquarium Heater

Uniclife Aquarium Heater Preset Submersible with Electronic Thermostat for 20 Gallon Fish Tank Heater 100W

For those looking for a preset aquarium heater that will warm your tank water, the Uniclife Aquarium Heater is the one for you.

With a constant temperature of 78°F, Uniclife is a compact heater for 25-gallon or smaller tanks that warms up quickly. Its built-in electronic thermostat LED indicator light displays red when heating and will automatically shut off when the preset temperature is reached.

To start heating the tank to the desired water temperature, leave the shatter-resistant heater fully submerged vertically or horizontally in your aquarium. Attach the suction cups to your tank and let your betta fish enjoy its warm water!


  • Has a shatterproof feature
  • Efficient heating


  • Non-adjustable temperature
  • Weak suction cups

4. UPETTOOLS Submersible Aquarium Heater

UPETTOOLS Submersible Aquarium Heater Preset Heater with 78°F Electronic Thermostat and UL Listed (100W) High Temperature Protection 2 Suction Cups

Another preset aquarium heater on the list is the UPETTOOLS Submersible Aquarium Heater.

This is the perfect fish tank heater for keeping your aquatic friends happy and healthy as it is designed to be submersible and easy to use, making it a great choice for any aquarium.

The temperature display is very easy to read, with its indicator lights signaling if the heater is on or not. UPETTOOLS automatically maintains an ideal temperature of 78°F, which is safe for both freshwater and saltwater fishes.


  • Has a shatterproof feature
  • Affordable
  • No thermometer needed


  • Non-adjustable temperature

5. Uniclife Aquarium Heater with Thermometer

Uniclife 100 Watt Aquarium Heater with Thermometer, Fish Tanks Heater for 10-25 Gallon

Uniclife Aquarium Heater with Thermometer is a must for tropical fish enthusiasts. This aquarium heater quickly and easily attaches to the side of your tank and provides reliable heat, making it the perfect choice for your tropical fish tank.

The built-in thermometer ensures accurate temperature readings, so you can always ensure that your tank is at the right temperature for your fish. Reach your desired temperature by turning the top red knob within the range of 68°F-93°F.

In addition, Uniclife includes a stick-on thermometer that will show the current water temperature of your tank. Monitor your tank’s temperature by checking the blue mark on your thermometer.


  • Good value for money
  • Comes with a stick-on thermometer
  • Automatic shut-off
  • Adjustable temperature


  • Durability
  • Glass casing may tend to shatter

6. HiTauing Aquarium Heater

HiTauing Aquarium Heater, 50W/100W/200W/300W/500W Submersible Fish Tank Heater with Over-Temperature Protection and Automatic Power-Off When Leaving Water for Saltwater and Freshwater

HiTauing Aquarium Heater boasts an intelligent temperature control system that allows your pet fish to live a safe and warm experience. This submersible heater comes with an external temp controller that digitally displays the water temperature of your tank.

It will automatically stop heating once it finishes heating the water. At this moment, the indicator light of the controller will turn green. The heater’s shell is composed of plastic material and can be disassembled into four parts, which makes it convenient for you to clean away any buildup of impurities contained in the heating rod.

Another thing that makes this heater cool and unique is its ability to switch between Fahrenheit and Celsius freely. Just press and hold the side button of the controller for around 3-5 seconds to choose between the two temperatures.


  • Has a LED temperature display
  • Multi-functional controller
  • Can choose between Fahrenheit and Celcius
  • Sturdy
  • Detachable cover


  • More expensive than other heaters
  • Bulky

7. KASANMU Aquarium Heater

KASANMU Aquarium Heater 50W/100W/200W/500W Temperature Adjustable Fish Tank Heater Suitable for Saltwater and Fresh Water

Like most aquarium heaters, KASANMU Aquarium Heater has an adjustable temperature range of 68°F-93°F that automatically stops heating once the set temperature is reached.

Before using, make sure to adjust the temp to your actual average room temperature. Attach the suction cups firmly while the heater is fully submerged in the water. Finally, turn it on.

As the heating rod heats rapidly, it is necessary to install KASANMU heater where the water flow in the aquarium is as fast as possible. This is essential to heat the water uniformly.

It is not advised to place the storage tank of the heating rod in the sand and gravel at the bottom of the aquarium, as this may cause damage to the heating rod.

When cleaning is required, remove the power plug and wait for the temperature to go down before taking the heater out.


  • Affordable
  • Has an anti-explosion crystal glass
  • Adjustable temperature


  • Not so good suction power
  • Durability

8. YukiHalu Small Submersible Aquarium Heater

YukiHalu Small Submersible Aquarium Heater, Mini Fish Tank Heater 25W 50W 100W 200W with Built-in Thermometer, External Temperature Controller, LED Display, Used for 5/10/20/40 Gallons (25 Watts)

YukiHalu Small Submersible Aquarium Heater is a compact heater that has an advanced intelligent frequency conversion technology. With its small design, this heater doesn’t take up too much space, giving your betta more room to swim.

Thanks to its advanced technology, the water temperature can be precisely kept with an accuracy of 1°F. The heater’s working frequency will be modified according to temperature fluctuations and will stop operating when the set temperature is reached.

Use an external controller to set the temperature instead of immersing your hands in water to control the dial. Don’t get your hands wet or contaminate the water tank.


  • Has a LED temperature display
  • Multi-functional controller
  • Compact design
  • External temperature controller


  • Short power cord

9. Bnzaq Aquarium Heater

Fish Tank Aquarium Heater - Adjustable Temperature Submersible Thermostat Heater,25W/50W/100W/150W/200W/300W

Bnzaq Aquarium Heater is made from shatterproof glass that doesn’t break too easily. The temperature is adjustable like most heaters, enabling your betta to enjoy a relaxing environment.

Bnzaq automatically regulates and maintains the set temperature range displayed in an easily readable temp indicator. Turn the knob at the top of the heater to change and control your tank’s temperature.

When placing the heater in the tank, remember to place it near the pump or filter to maintain even water temperature. Unplug the heater 30 minutes ahead of time when changing the water for the fish tank.


  • Inexpensive
  • Displays both Celcius and Fahrenheit temperature


  • Separate thermometer is needed for accurate temp reading
  • Short lifespan
  • Stiff knob

10. Fluval M100 Submersible Heater

Fluval M100 Submersible Heater, 100-Watt Heater for Aquariums up to 30 Gal., A782

The Fluval M100 Submersible Heater is an excellent option for aquariums up to 30 gallons and has a temperature range between 66 and 86°F.

This compact heater lives up to its reputation for protection and efficient performance, which is also known for its reflective technology that maintains the aquarium’s natural look as the heater reflects the color of the tank’s surroundings.

In addition, the Fluval M100 has a very sensitive and reliable thermostat that allows for an accurate temp reading. It’s also shock and heat-resistant, made possible by its borosilicate glass that protects the heater and allows for even temperature distribution.


  • Matches the color of the tank’s surroundings
  • Easy-to-adjust temperature dial
  • Durable
  • Sleek and compact design


  • More expensive than other heaters
  • No digital display

Buying Guide For Best 20-gallon Heater

Type of heater

The most common heaters in the market are submersible heaters. Although there are more types of heaters, submersible heaters remain popular due to their compact design and affordability.

If you prefer other types of heater, you can choose whichever you like. Just make sure to research first the pros and cons of different tank heaters and carefully choose which will best fit your fish and tank set.


Power is an important consideration when looking around for water heaters. Without adequate power, you risk incomplete heating. For 20-gallon tanks, it’s imperative that a heater uses at least a minimum of 50 watts. Any wattage less than 50 results in a poorly heated tank, affecting your fish’s environment and health.

Materials used

Quartz fiberglass has proven to be the most durable core material for heaters, but keep in mind that they can still break under specific circumstances.

Alternative to quartz glass is titanium, which is also very durable and doesn’t shatter easily.

Temperature range

A heater’s temperature range is critical for the survival of aquatic life. You will find many heaters that will cover a temperature range of 68-90°F, but there are also a few that will let you set an appropriate temperature in a wider range.

Some heaters have a preset temperature and cannot be adjusted that’s why heaters with an adjustable temperature range are preferable. This offers more flexibility to change the temperature according to your demands.

Commonly Asked Questions

What are the types of aquarium heaters?

Submersible heaters

Submersible fish tank heaters are a great way to keep your tank warm while you’re away. These small, compact units can be attached to the side of your tank while fully submerged and use warm water to heat up the tank. They’re also relatively low-maintenance, requiring only a small amount of water flow to maintain a comfortable temperature.

Submersible heaters are available in two types: active and passive models. Active models use a heating element to produce heat, while passive models rely on the environment to provide heat.

Hanging heaters

Hanging heaters are amongst the most typical and cheapest heaters. Many people who have just acquired an aquarium use hanging heaters to ensure the proper water temperature for their pet fish.

As the name implies, this type of heater hangs from the top edge of the fish tank, typically from behind the tank, and features a glass tube with a heater component within.

It is advisable that you make sure that your fish tank heater is safe to use for your fish, as this could crack the protective seal on it and lead to electrocution or fire.

Substrate heaters

Another type of fish tank heater is the least commonly used one, which is the substrate heater. A coil or a grid of wire is stored in an insulator buried underneath gravel or substrate. This wire itself is the element for the heater and starts heating when turned on.

Eventually, the heat will transfer to the gravel, which will help warm the whole tank.

Filter heaters

Some models of filters integrate heaters in their designs. How it works is that the water passing through the filter gets heated and then returned to the water.

Since most of these heaters are integrated with the filter, some call this type the in-filter heaters.

Do I need a fish tank heater?

Many fish tank enthusiasts swear by the benefits of a fish tank heater. Some people say that it’s beneficial to keep the water at a comfortable temperature so that fish can swim and feed properly.

Other enthusiasts claim that fish tank heaters are necessary to prevent their tanks from freezing in winter. So which is it? Do fish tank heaters work, or are they just a waste of money?

The answer to this question is a little complicated, as the need for a fish tank heater can depend on several factors.

Before making that decision, you may consider the following factors first.

  •  First, make sure your tank is large enough for the size of the heater you want.
  • Second, research which type of heater is the best for your tank and what features are important to you.
  • Third, consider how often you will use the heater and how much it will cost to operate.
  • Finally, read the manufacturer’s instructions before installing your new fish tank heater.

In general, though, fish tank heaters are useful if your aquarium temperature falls below 72 degrees Fahrenheit. Heaters can also be helpful if you have a large tank or one with many plants.

Can I use a 300W heater in a 20-gallon tank?

300 watts per gallon is, however, too big. The heater usually needs less than half the recommended wattage for tanks. I prefer having the tank a little cold overnight instead of overheating, and the chances of both failures are very low.

Is a 50-watt heater good for a 20-gallon tank?

A 50-watt heater should suffice for 20-gallon tanks in a warm room (78 degrees), but its effectiveness decreases in a warmer aquarium to just be used for 15-gallon tanks. Here is the basic breakdown of aquarium heat output depending on what tank your boat is using.


The best aquarium heater for a 20-gallon tank is:

An aquarium heater for betta tanks is a must-have for any fish keeper. A fish tank without an aquarium heater will quickly become too cold for your betta and other fish.

Moreover, heaters can be a lifesaver for bettas during cold climates. Heaters are available in electronic and mechanical styles and come at various prices.

Choosing the right heater for your fish tank is essential, as not all heaters are safe for bettas. Hopefully, from the lists above, you’ve decided what heater to get for your 20-gallon tank!

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