The Best Aquarium Heaters to Create a Happy Home for Your Fish

Best Overall

FREESEA Aquarium Heater Fish Tank Submersible Heater

4.8

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Thanks to this heater’s real time temperature displayed in large, easy-to-read LED, you won’t have to buy a separate thermometer. Better yet, you gain peace of mind that your tank is always the right temperature because the heater will automatically turn on if the tank water drops below your set temperature. This heater can also be installed on the side or bottom of your tank for flexibility when designing your aquarium.

This fully submersible thermometer can heat the water in a tank from one to 10 gallons anywhere from 59 to 94 degrees Fahrenheit, making it a smart choice for saltwater or freshwater fish. The heating function automatically kicks on and off as needed, and you control the temperature via a touch button on the cord. Be sure to avoid submerging the cord underwater as this portion of the heater is not waterproof. Turn the power off on the heater at least 10 minutes before cleaning or changing the water in your fish tank.

Best for Large Tanks

Orlushy Submersible Aquarium Heater, 500W

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Large tanks require stronger heaters, and this 500-watt unit can keep tanks up to 100 gallons in a fish-safe range of 68 to 89 degrees. It’s 13 inches long and does need to be fully submerged in water to work. If your tank isn’t that deep, consider buying two smaller heaters, something experts recommend for a more even distribution of heat (you’ll want to place the heaters on opposite ends of the tank). You set the heat via a temperature control knob on the heater and can tell that it’s working by the red indicator light. It has a long, 6-foot cord.

Best for Small Tanks

Eheim Jager Aquarium Thermostat Heater

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This old school aquarium heater from German company Eheim will keep the water in your smaller aquarium—up to 10 gallons in size—in a healthy range of 65 to 93 degrees. You can use the TruTemp dial to precisely recalibrate the heater by up to 8 degrees in either direction if you notice it running slightly high or low. It has a thermo safety control, which will automatically turn it off if/when your tank starts to run low on water. With double suction cups, the heater readily sticks to the side of your tank. It’s made of shock-resistant and shatterproof glass.

Best for Betta Fish

Marina Betta Submersible Aquarium Heater

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This thin, flat 8-watt heater is designed specifically with betta fish in mind. It is safe to use in plastic or glass tanks up to 1.5 gallons in size and keeps the water warmed to 75 to 85 degrees. (Experts recommend betta fish live in 75 to 80 degree water).

This heater doesn’t have an on/off switch, but you’ll know it’s working thanks to its red indicator light. When it’s time to clean the tank or switch out the water, unplug it and let it cool for 15 minutes first. The exterior is made of a polymer that’s more durable than traditional glass, which you’ll appreciate during those cleanings.

Best Splurge

Innovative Marine Helio PTC 200 Watt Aquarium Heater w/ Controller

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This heater costs more than others, but those who are serious about their in-home marine reef aquariums say the innovations are well worth the investment. For starters it has two 100-watt heaters to safely heat up to a 50 gallon tank. It does so using Positive Temperature Coefficient (PTC) technology, meaning it contains solid state ceramic chips. This allows the device warm up quickly, and heat evenly with no hot spots, and keep a low surface temperature. It's self-regulating to turn off when it reaches a predetermined set temperature.

Should there be any unexpected temperature fluctuations, the Smart Controller will instantly alert you. An additional benefit is that this heater uses less energy than some similar models.

Best Electronic

hygger Fast Heating Titanium Aquarium Heater

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With a large, easy-to-read LED temperature display, you’ll always rest assured that your finned friends’ home is at the exact right temp. The submersible heater is made of premium titanium and double sealed by a black protective guard, which means should your fish touch it they won’t get burnt and the heater itself is resistant to explosion and corrosion.

It includes a run-dry protection that automatically turns the unit off if the water gets too low. An external temperature control means you won’t have to get your hands wet when you want to adjust the temp. The 500 watt unit is made for fresh or saltwater tanks 60 to 120 gallons in size.