How to Choose the Right Aquarium Heater for Every Tank

From the tropics to your living room, maintaining adequate water temperature is a challenge many aquarium enthusiasts face. Beginners and even old pros may wonder what the best heater is for their tanks. With so many varying opinions muddying the waters, Bluefish Aquarium has put together this simple guide on making every aquarium feel like a mini island getaway complete with warm waters and happy fish.

Tank Size

There's no one-size-fits-all approach to aquarium husbandry, but there are a few rules of thumb that can make heating your tank a little easier. Generally speaking, it's a good idea to maintain 5 watts of heat per gallon of water. This keeps the temperature at a constant 10 degrees above room temp. 

Let's say you have a standard 25-gallon aquarium. Installing a 150 watt heater, along with a secured lid for retaining warmth and preventing evaporative cooling, should be sufficient for keeping the temperature around 76-80 degrees Fahrenheit. If you're housing your fish in a cooler location, such as a basement or near a window, adjust accordingly by upgrading to the next highest wattage.  


Arranging your fishy friend's furniture is more than simply installing a castle or two. Heater placement is important for providing proper circulation throughout the tank. Most hobbyists swear by submersible heaters that sit comfortably below the water level and provide heat throughout the entire tank thanks to the help of the current. These kinds of heaters should be placed next to the filter to maximize flow and oxygenation. Angle the heater roughly 45 degrees and dress it up with plants and clever camouflage so as not to detract from the interior decor of your tank.

Species Specific Needs

We've discussed the 76 to 80 degree comfort zone of most home aquariums. However, some species require warmer or cooler waters in order to thrive. Consider where in the ocean your fish reside. Tropical creatures require more "sun" exposure which can be supplemented with UV bulbs and radiant heating, while bottom feeders prefer slightly colder temperatures.

The best way to maintain constant aquarium conditions is to monitor the temperature daily. Mount a thermometer to the wall opposite the heater. Check to ensure heat is reaching the entirety of the tank and adjust as needed.

Having trouble finding the sweet spot when it comes to aquarium temperatures? Ask our experts and avoid getting into hot water with your fishy friends!

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