Heaters & chillers, Equipment, Reviews

Best 5-Gallon Aquarium Heaters for Freshwater Fish Tanks

Our Top Picks 

Overall Best – FREESEA 50W Aquarium Heater

FREESEA’s aquarium heater is an excellent choice for small tanks. Its compact design, easy-to-use interface, and concealed heating element make it the best nano aquarium heater on the market.

Best for Budget  – Aqueon Pro Submersible 50W Heater

The Aqueon Pro submersible heater is an excellent choice for budget-minded aquarium enthusiasts. I’ve used one personally and can vouch for its durability – it’s able to take a few knocks without breaking. 

Best for Safety – Eheim Jager Aquarium Thermostat Heater

With the Thermo safety control, you don’t have to worry about your heater running dry and ruining your device. If you remove it from the water or if the water level dips too low, no problem! The safety feature will automatically shut off to prevent any damage. 


Having a smaller aquarium requires more diligence to maintain a stable water temperature. Why? With less water, small tanks are more volatile to changes in temp. Fluctuating temperatures put your fish under undue stress, which can quickly lead to their death. So, how can you maintain a consistent temperature in your aquarium to ensure the health and happiness of your fish?

The answer is finding the best small heater for your tank! Most people think that keeping a fish tank requires lots of work. But it’s really not – as long as you have the right equipment. That’s why we put together this guide to the best 5-gallon aquarium heaters on the market today.

You’ll be able to find the perfect heater for your tank in no time at all with our help. We’ve done all the hard work for you, so all you need to do is make your selection and add it to your shopping cart.

The 6 Best Aquarium Heaters for 5-Gallon Freshwater Fish Tanks

FREESEA 50W Aquarium Heater

Sale
FREESEA 50W Mini Aquarium Heater Fish Tank Submersible Heater with LED Temperature Display
7,514 Reviews
FREESEA 50W Mini Aquarium Heater Fish Tank Submersible Heater with LED Temperature Display
  • ★ Temperature range: 59°F~94°F, display Fahrenheit °F, this heater is designed for1~10 gallons tank. Upgrade function: The heater will auto shut off when it is out of water and turn normal when fully in water again.

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

Freesea’s aquarium heater is a feature-packed, space-efficient unit perfect for small tanks that are both easy to use and conceal. The 50-watt version can maintain the optimum temperature in up to a 10-gallon tank, but we recommend it more for 5 gallons–especially during cooler months when heating is needed most.

This small yet powerful machine only measures 3.7 x 1.5 x 2.5 inches, making it one of the smallest heaters on the market! This heater is perfect for those who like to have a lot of control over the temperature. With a range of 59-94°F, you’ll be able to find the perfect setting for any situation.

Product Specifications 

  • Size: 50-100 Watt
  • Touch button, cyclic adjust temperature
  • Built-in electronic thermostat 
  • Temperature range: 59°F~94°F
  • Auto Shut-Off when overheated

Pros 

  • Multi-function LED digital display heater
  • Fully submersible
  • 12 Month Warranty 
  • 24-Hour Professional After-sales Service
  • No need to buy another thermometer

Cons 

  • Smaller cord than other heaters
  • Fish can get trapped

Aqueon Pro Submersible 50W Heater

Sale
Aqueon Pro Adjustable Heater, 50W
883 Reviews
Aqueon Pro Adjustable Heater, 50W
  • Adjustable heat setting 68 to 88°F, Electronic Thermostat accurate to +/- 1°

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

If you’re looking for a submersible heater that won’t break the bank, the Aqueon Pro is perfect for your 5-gallon tank. You can easily adjust the temperature to anywhere between 68-88°F, making it ideal for any type of fish.

One advantage is that it’s designed to be long-lasting and won’t quickly shatter. Additionally, the LED light lets me know the heater’s status; if the light is red, then the tank is still heating up, but if it’s green, that means the set temperature has been reached. Once at your chosen temp, it’ll turn off automatically–so there’s no risk of overheating!

Product Specifications 

  • Size: 50 Watt
  • Made in Italy 
  • Heating Method: Forced Air, Fan & forced air
  • Adjustable heat setting 68 to 88°F
  • Electronic Thermostat accurate to +/- 1° 
  • Auto Shut-Off when over-heats

Pros 

  • LED light is always on
  • Fully submersible
  • Limited Lifetime warranty
  • Comes in two different colors
  • Easy to set up

Cons 

  • The startup time is slow
  • Suction cups can be difficult to stick

Eheim Jager Aquarium Thermostat Heater

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

Eheim offers Jager aquarium heaters of varying wattages, from 25 to 300 Watts. The 50 Watt heater is best for tanks holding 5 to 10 gallons. However, with dimensions at 9.6 inches long and 1.4 inches in diameter, it’s larger than most small heaters—but still able to fit in a 5-gallon tank measuring 16x8x10 inches if placed diagonally across the tank.

The heater gives you full control with a wide temperature range from 65 to 93°F, so you can get your water heated to the perfect temperature for any type of fish. You can set the temperature in 0.5°C (about 0.4°F) increments, more precisely than other heaters available on the market today.

Product Specifications 

  • Size: 25 to 300 Watts
  • Control accuracy is +/- 0.5° C
  • Thermo safety control
  • Temperature range: 65 to 93°F

Pros 

  • The large temperature dial 
  • Shatterproof glass
  • Simple and safe recalibration (±2 °C)
  • Resistant to chemical and biological substances
  • It will automatically turn off when the water level dips too low

Cons 

  • Unnatural look
  • It will occupy a lot of space

Cobalt Aquatics Neo-Therm Aquarium Heater

Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat (Fully-Submersible, Shatterproof Design) from 25W to 300W
997 Reviews
Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat (Fully-Submersible, Shatterproof Design) from 25W to 300W
  • Super-flat design. Fully submersible, modern design for energy efficient Aquarium and terrarium heating. Includes reversible holster/bracket, which allows heater to face inward or outward. See the product images to determine the best neo-therm size for your tank.

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

The Cobalt Aquatics Neo-Therm Heater would have been our top pick if it hadn’t been for the high price tag. When picking the best heater for a 5-gallon betta tank, you must factor in both quality and customer budget. While some might see this heater as justified in its expense, many people cannot afford it– knocking it down on our list.

The Cobalt Aquarium Heater has a long lifespan, meaning once you purchase it, you likely won’t need to again for years. Additionally, many customers report that the company is quick to resolve any issue should something go wrong. This is key because when your heater breaks, you don’t have time to wait around.

Product Specifications 

  • Size: 25 to 200 Watt
  • Made in Poland
  • Includes reversible holster/bracket
  • Temperature range 66-96°F
  • Maintain Tank temperature within +0.5°F
  • Auto Shut-Off when over-heats

Pros 

  • Led displays both set temp and actual temp
  • Fully submersible
  • Limited 3-years warranty
  • Indestructible
  • Blends in the tank’s existing decor

Cons 

  • Highly expensive
  • It can only be adjusted in 2°F increments

Tetra HT Submersible Aquarium Heater With Electronic Thermostat

Tetra HT Submersible Aquarium Heater With Electronic Thermostat, 50-Watt
11,888 Reviews
Tetra HT Submersible Aquarium Heater With Electronic Thermostat, 50-Watt
  • All Tetra HT heaters have indicator lights to let you know when the heater is on. It will be red when heating and green when the proper temperature has been reached.

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

The Tetra HT10 submersible aquarium heater is an excellent budget choice for nano tanks ranging from 2-10 gallons. Its short 5.25-inch length and 1.6-inch diameter make it a perfect fit for 5-gallon tanks, and you can mount it either vertically or horizontally to suit your needs better.

The heater is preset to 78°F and does not give the option to adjust the temperature, but it will stay at that consistent degree. The 50 Watt HT10 is a great option for most people, but if you live in a colder climate or are heating a 5-gallon tank, the 100-watt version is a better option.

Product Specifications 

  • Size: 50 Watt
  • Made in the USA
  • Built-in electronic thermostat 
  • Automatically maintain water at 78° F
  • Auto Shut-Off when over-heats

Pros 

  • Simple indicator light
  • Fully submersible
  • Work in aquariums ranging from 2 to 55 gallons
  • Inexpensive
  • Will shut off if an electrical short is detected

Cons 

  • There are some complaints about the HT10 overheating
  • Build quality is compromised
  • Have only one suction cup

Fluval Marina Submersible Heater for Aquarium, Mini

Fluval Marina Submersible Heater for Aquarium, Mini, 50-watt
156 Reviews
Fluval Marina Submersible Heater for Aquarium, Mini, 50-watt
  • Mini, 50 Watt submersible heater for fresh or saltwater aquariums

Last update on 2023-02-05 / Affiliate links / Images from Amazon Product Advertising API

The 50 Watt submersible heater from Marina is the perfect solution for heating a 5-gallon aquarium. Its small size (6 inches in length) makes it a perfect fit for any 5-gallon fish tank around 12 inches tall. 

The heating indicator light on this unit tells you when the water is being heated, as opposed to when it’s turned off. Note that the temperature dial doesn’t have an indicator, so all you’ll see is a plus and minus symbol. Because of this, you’ll need a thermometer in your tank to check that the level is correct.

Product Specifications 

  • Size: 25 to 50 Watts
  • Includes bracket with suction cups
  • Impact-resistant glass design
  • Waterproof sealing
  • Temperature range: 68 to 82 °F

Pros 

  • Small yet powerful
  • Easy use, safety, and convenience
  • On/off pilot light indicator 
  • Bumper guard for fish safety
  • Easy-to-access temperature set the dial

Cons 

  • Struggle to reach the high end of the temperature range
  • A thermometer is needed in the tank

How to Pick the Best Aquarium Heater For You

When you’re looking at all of the different heaters on the market, it can be tough to decide which one is right for you and your fish. Keep these factors in mind when making your purchase so that your new stand meets (and hopefully exceeds) all of your expectations.

Size and Power of the Heater

The size and power of your small aquarium heater are determined by

  • The volume of your tank.
  • The temperature of your room.
  • The temperature you need to maintain in your water.

The majority of power recommendations for tropical fish are founded on a temperature range between 74-80°F, with an average room temperature falling in at 68-72°F. During the winter months, when it gets colder, though, you’ll need to select a heater with more power.

Even if you have a tiny aquarium, this won’t damage your fish as the thermostat will turn it off once it reaches the desired temperature. If your room gets colder in winter, having a more powerful heater will allow it to maintain the optimal temperature for your fish.

The wattage of the heater

A heater’s power is typically measured in watts (W). As a general rule of thumb, it takes approximately 2.5 to 5 watts to heat 1 gallon of water. So, using the high end of this range as an estimate, a 5-gallon fish tank would need a 25-watt heater.

The table below shows how much wattage is required for different-sized nano aquariums, with the maximum being a 10-gallon fish tank. It’s all dependent on keeping the room temperature at 72°F so that the fish’s environment will be between 74 to 80°F.

Tank Size Power of Heater to maintain 75 to 80°F
3-Gallon 15 Watts
5-Gallon25 Watts
10-Gallon50 watts

But don’t forget to look into your fish’s specific needs before making a purchase, and if you have species that require a higher temperature or if your room gets cold in winter, opt for a heater with more wattage.

The Readability of Temperature 

You should always go for a heater with a temperature gauge that is simple to read and displays the temperature in single-degree increments. This will allow you to be certain of the precise setting. Some models also have digital displays, which can make monitoring the temperature even easier.

Temperature Control and Adjustment

There are two types of small aquarium heaters when it comes to temperature control.

Preset

These heaters are less expensive, but you cannot adjust the temperature from the usual 78°F. If you have fish that require a different climate, then a preset heater will not work for you.

Adjustable

The adjustable heater gives you the power to set the temperature to your specified range, which is normally between 65 and 95°F. They can be larger than other types of heaters, however, so make sure to pick one that won’t overcrowd your small aquarium.

Only Buy Heaters That Are Safe

Here are some of the safety features that must be present in your heater

  • The heater should be fully submersible – because if the heater is positioned incorrectly or run out of water, there is less chance of shattering.
  • The heater must have an automatic shut-off.
  • There should be an indicator light in the heater that will indicate your heater is working.
  • Bumper guard – This will stop your fish from coming into contact with the heater’s surface or heating element and getting hurt.
  • Use a shatterproof glass or plastic heater to avoid any potential hazards.

Conclusion 

You have a few options for heaters that will work with your 5-gallon tank, but the best pick relies on both what you can afford and which features matter most to you. An essential factor to bear in mind is the heater’s wattage, though. Be certain that the deemed heater has enough power specified for use with a 5-gallon tank before shelling out any money.

Frequently Asked Questions (FAQs)

Is a 25W Heater Enough for a 5 Gallon Tank?

A heater’s power is typically measured in watts (W). As a general rule of thumb, it takes approximately 2.5 to 5 watts to heat 1 gallon of water. So, using the high end of this range as an estimate, a 25-watt heater will do well for a 5-gallon fish tank.

How Do I Choose a Heater for My Fish Tank?

The general guideline for aquarium heaters is 5 watts per gallon if your aquarium holds 55 gallons or less and 3 watts per gallon for those over 60 gallons. Also, if the temperature in your home is typically cooler than average or if the aquarium will be placed near an exterior door/wall, opt for a bigger heater or get two heaters instead of one.

Does It Matter Where the Heater Is in Fish Tank?

For even and consistent heating throughout your home aquarium, the best place to put your heater is near areas of maximum water flow, like the outlet from your filter or powerhead.

About

Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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