Best* Submersible Heaters of 2022

An aquarium heater is a vital element of the aquarium for most species of fish. Fish are coldblooded and rely on the water temperature to maintain their body heat. Water that is too cold can increase stress on your fish and raise their risk of disease.


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From some of the best compact aquarium heaters to the best inline aquarium heaters and our most efficient aquarium heaters, we’ve got the solutions you need to create a top-notch haven for your fish.

Aqueon Submersible Aquarium Heater


Submersible Aquarium Heater

This fully submersible aquarium heater gives great consideration to accuracy and safety and includes a lifetime warranty. With thermal shatter-resistant glass, precise heating and auto-shut off to avoid overheating, this heater is an excellent option for the large home aquarium. The electronic adjustable thermostat has precision +/- 1 degree Fahrenheit and has an LED light that illuminates when heating. Suction cups allow for easy installation within your aquarium. This fully submersible heater can be installed horizontally or vertically.

  • Available in Wattage Max 50 to 300
  • Fully submersible
  • Electronic thermostat
  • LED illuminates while heating
  • Precision to +/- 1 degree Fahrenheit
  • Adjustable temperature settings

Aqueon Preset Aquarium Heater


Preset Aquarium Heater

The Aqueon Preset Heater is one of our best aquarium heaters for a 20-gallon tank. It includes many of the same safety features of their adjustable heater, including a shatter-resistant construction and a safety shut-off for protection against overheating. This heater is also fully submersible and will display a red LED indicator when it is heating. Unique to this heater, it is also a no-stress way to keep your aquarium at a temperature that most tropical fish find comfortable and will maintain at 78F, with no adjustment needed.

  • 50 Wattage Max
  • Fully submersible
  • Shatter-resistant constructions
  • Automatic safety shut-off

Aqueon Mini Heater


Mini Heater

Need a heater for your betta or other fish in a small desktop aquarium? The Aqueon Mini Heater is one of the best compact aquarium heaters around. It’s shatterproof, fully submersible and features the thermal safety shut-off just like its larger counterparts—but in a compact size for aquariums up to 5-gallons. This heater comes preset to the correct temperature to keep your aquarium water at an ideal temperature and contains a thermal safety shut-off for the wellbeing of your aquatic life.

  • 10 Wattage Max
  • Submersible heater
  • Precise temperature within +1 / -1 degrees Fahrenheit
  • Shatter-resistant construction
  • Thermal safety shut-off

Aqueon Mini Flat Heater


Mini Flat Heater

The Aqueon Mini Flat Heater is a tiny submersible heater that is one of the best aquarium heaters for glass or acrylic aquariums between 1- and 2.5-gallons. This heater includes suction cups to mount to the side or bottom of the tank. Its flat design means it takes up little space in your tiny desktop aquarium. Shatterproof construction makes it a great option for heating small tropical aquariums.

  • 5 Wattage Max
  • Fully submersible
  • Vertical or horizontal placement
  • Shatterproof construction
  • Quick and easy installation

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Learn More About Submersible Aquarium Heaters

Choosing the right aquarium heater for your tank is not a place to cut corners. Your fish will rely on your heater to moderate their body temperature. An unreliable or inaccurate heater could cause stress and illness in your fish or even fatalities if it breaks down.

When looking for the best and most efficient aquarium heater, the first step is to choose the right size heater. A good rule of thumb is that your heater needs to generate 5 watts for every gallon you want to heat 10 degrees above room temperature if your tank has a lid—which will help retain warmth. In this scenario, the best aquarium heater for a 150-gallon tank would require a heater that can produce 750 watts. Pet parents with large tanks like this may prefer to install two heaters to manage the water temperature. This can also help make the tank more stable in case one heater breaks down.

Other than choosing a heater of the appropriate power level, other factors to look for in your aquarium heater are:

  • Overall reliability
  • Simplicity to install
  • Robustness—look for heaters that are “shatterproof” or “shatter resistant”
  • Clear LED display
  • Ability to adjust the temperature
  • Heater guard included
  • Visually pleasing design
  • Warranty—Many of the best aquarium heaters come with a 3-year or 5-year warranty

The best way to determine what is the best aquarium heater brand is to do your research. Read reviews. Ask the Aquatic Specialists at your neighborhood Petco Pet Care Center about their recommendations. Some of the top heaters can be pricey, but you can also find more affordable heaters that have also earned positive reviews.

Though it rarely happens, fish can get burned by your aquarium’s heater. This can occur if your fish gets stuck between the heater and the tank or if they hide behind the heater to avoid a threat. Certain fish are also drawn to the warmth of the heater, such as plecos or kuhli loaches.

The best way to protect your fish from heater burns is to use a heater guard to cover your heater. Most of the best aquarium heaters include a heater guard, but you can also buy one separately and place it over your heater. A heater guard serves a dual purpose. It can also protect your heater from larger fish that might hit it.

It’s a good idea to install your heater near your filter inlet, filter outlet or circulating pump. This will help move the heat away from your heater and disburse the heat more quickly throughout your tank.

It can be difficult to tell if any of your fish have been burned by your heater. Fish are programmed to act as normally as possible so as not to attract the attention of predators. You might not notice any changes in their behavior even if they’ve been injured. Minor burns are difficult to see, though you may notice a light patch of skin on your fish or gills that may look transparent. Severe burns are more noticeable. You may see a wound on your fish where their scales and skin are gone.

For minor or moderate burns, the biggest risk to your fish is not the burn itself but a secondary infection. If you suspect your fish has gotten burned by your heater, you can take several steps to help lower the chance of the wound becoming infected.

The best actions to take are:

  • Add salt to your tank, which can help your fish with osmoregulation, a process where they use water and salt concentrations to maintain the right fluid pressure in their bodies. By assisting your fish with osmoregulation, you’ll allow them to spend more energy on healing their wound.
  • Add a board-spectrum antibiotic to your tank to help kill off bacteria and other microbes that could cause an infection in your injured fish. However, this treatment may change the chemistry of your tank, so consider moving your injured fish into a quarantine tank.
  • Add wound seal to your tank, which can help your fish restore their protective slime coating. This can also help keep their immune system strong.
  • Clean your aquarium regularly to help prevent secondary infection. Remove uneaten food, perform regular water changes and make sure your filter is working correctly.

For the most part, high-quality aquarium heaters that are installed correctly are not dangerous. However, even in the best scenarios, problems can occur. Here’s what to look out for.

First, make sure you purchase a heater with enough wattage to heat your tank. Larger tanks will need heaters with more wattage or may require that you install multiple heaters. If your heater isn’t powerful enough for your tank, it won’t be able to heat the tank adequately, which could stress or harm your fish.

Next, make sure you know the ideal temperature for your aquarium. Different fish prefer different temperatures. For example, tropical fish do best in water that is 75 to 80 degrees Fahrenheit. If you set your heater too high or too low, your fish could suffer.

Another big danger is installing your heater so that it touches the glass or the gravel in your tank. This can create a temperature gradient which adds tension to the glass. It could result in the glass of your tank shattering.

Finally, an aquarium heater without a heater guard represents a danger to your fish. Though unlikely, it’s possible that your fish could get stuck between the heater and the glass, which could result in burns on your fish. The best way to avoid this danger is to purchase an aquarium heater with a built-in guard or to purchase and install a separate heater guard around your heater.

*Based on sales data.