Aquarium Heater

Many tropical fish keepers do not think about the need for an aquarium heater. Let’s think about one of the key words in Tropical Fish Keeping. The word “Tropical” is the word I want you to remember when you can’t figure out the correct water temperature of your home aquarium tank.

All tropical fish have a specific water temperature in which they will thrive, but almost all tropical fish live in water temperatures ranging from 70°F to 80°F. The most common species that we keep in the hobby will thrive in water temperatures between 76°F – 80°F.

So who needs a heater in their tropical fish tank? 

The answer is everyone, unless you live in a tropical climate and have no air conditioning running in your home.

Can you get away with not having an heater in your aquarium? Yes, but most often you will have problems with major water temperature fluctuations and this can cause many problems.

When I say that you can get away without a fish tank heater, this means that you are keeping your house and aquarium temperature in this tropical fish temperature range mentioned above. This means no turning on the air conditioner in the summer and the air blowing near the aquarium or cutting back the thermostat on the heater in the winter to conserve electricity while your at work.

The truth is your tropical fish will be healthier, happier, and live longer if you provide a stable, consistent water temperature and this is accomplished by installing aquarium heaters in your tropical fish tank.

There are two main fish tank heaters used in the tropical fish keeping hobby.

Please click on each link below to learn more about each type of aquarium heater.

Heating Your Tropical Fish Tank

When you begin researching and shopping for aquarium heaters, you will notice they are rated or categorized by Wattage. Most fish tank heater manufacturers will provide a chart so you can ensure you purchase the correct size aquarium heater.

Here is the safe way to estimate how much heater you actually need.

First, you need to allow for 5 watts per gallon of water you will be heating. So if you have a 40-gallon tropical fish tank, you will need 200 watts of heater in your aquarium tank. 

So does this mean you need to purchase one 200W heater?


I suggest you purchase two 100W heaters. You are probably asking why would I want to purchase two smaller heaters? The reason I suggest this is because if you have two smaller heaters you will be less likely to run into the nightmare of a heating disaster. There are horror stories of heaters getting stuck in the “on” function and overheating the tank killing all the fish in the aquarium.

The idea is that if you have two smaller heaters running, there will be less work on each individual heater and therefore lowering the risk of a malfunctioning heater. Then there is the opposite situation, if by chance one heater stops working; you will have an extra heater to maintain the temperature in the aquarium.

Aquarium Thermometer

Now that you know you need a heater to keep your tropical fish happy and healthy, we need to discuss how you will ensure your aquarium is at the correct temperature.

Please read more about the Aquarium Thermometer to ensure you have the best thermometer to monitor the temperature in your aquarium tank.

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