Aquarium Heaters

Choosing the Right Aquarium Heater

Choosing the right aquarium heater starts with your tank volume, room temperature and the temperature requirements of the fish or other livestock you keep.

Heater wattage is an important starting point, but it should not be used on its own. Always check the manufacturer's recommended aquarium size for the exact heater you are considering.

• Small aquariums: lower-wattage heaters may be suitable where the manufacturer recommends them for the tank volume.
• Medium aquariums: 100W to 200W heaters are common options, depending on tank size and room temperature.
• Larger aquariums: higher-wattage heaters or multiple heaters may be suitable depending on the setup.

If you're heating a compact aquarium, browse our nano aquarium heaters for smaller-tank options.

Submersible Fish Tank Heaters

Submersible fish tank heaters are one of the most common ways to maintain a stable temperature in a tropical aquarium. They sit inside the tank and work best where there is good water movement to help distribute heat evenly.

Many models include an adjustable thermostat so you can set a temperature suitable for your livestock. A separate aquarium thermometer is still recommended so you can monitor the actual water temperature.

In-Line Aquarium Heaters

In-line aquarium heaters are installed outside the aquarium as part of a compatible external filtration system. They heat the water as it passes through the unit, helping keep equipment out of the display tank.

This style can be a useful option for aquariums where a cleaner in-tank appearance is preferred and the filtration system is suitable for in-line heating.

What Temperature Should a Tropical Aquarium Be?

There is no single temperature that suits every tropical fish. Different species have different temperature requirements, so the heater should be set according to the livestock in your aquarium rather than using one universal setting.

Check the care requirements of your fish and monitor the tank with a reliable thermometer. Stable water temperature is generally more important than frequently adjusting the heater.

Where Should an Aquarium Heater Be Placed?

Place a submersible heater where water can circulate around it effectively. Positioning it near the outlet of an aquarium filter can help move warmed water through the aquarium.

Always follow the manufacturer's installation instructions, including minimum water levels, heater orientation and operating requirements.

Aquarium Heater Safety

• Follow the manufacturer's installation instructions for the exact heater model.
• Keep the heater submerged to the level specified by the manufacturer.
• Disconnect the heater before water changes or removing it from the aquarium.
• Allow heated glass units to cool before handling.
• Replace heaters with damaged glass, cables, plugs or seals.
• Use a separate thermometer to monitor the actual aquarium temperature.

Shop Aquarium Heaters in Australia

Aquaholics Online stocks aquarium heaters for small, medium and larger freshwater aquariums, including options from PetWorx, OASE and Aquael.

Shop online for Australia-wide delivery or visit our Baringa store on the Sunshine Coast for help choosing a heater suited to your aquarium.

Frequently Asked Questions

What size aquarium heater do I need?

Choose a heater using the manufacturer's recommended aquarium volume for that specific model. Tank size, room temperature and the temperature requirements of your livestock can all affect heater selection.

Where should I place an aquarium heater?

A submersible heater should be placed where there is good water movement so heat can circulate throughout the aquarium. Near the filter outlet is often a suitable position.

Do tropical fish need a heater?

Many tropical fish require water warmer than normal room temperature, but the correct temperature depends on the species. Check the care requirements of the fish you keep before setting the heater.

Should I use a thermometer with an aquarium heater?

Yes. A separate aquarium thermometer lets you check the actual water temperature and confirm the heater is operating as expected.

Can I use two heaters in a large aquarium?

Some larger aquariums use two appropriately sized heaters to improve heat distribution and provide redundancy. Heater selection should still follow the manufacturer's recommendations for the aquarium volume and installation.