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Do I Need a Heater for My Fish Tank and Why Do I Need It?

do i need a heater for my fish tank and why do i need it?

I’m quite certain that you know the many nuances of taking care of fish in a fish tank. You know that they require the right amount of mineral content, pH levels, saline levels, filters, and many more. But have you given thought to the right temperature for your fish tank? Have you asked yourself “Do I need a heater for my fish tank and if so, why?”

Here’s the guide you need regarding using a heater for your fish tank.


Do I Need a Heater for My Fish Tank?

If you are keeping a tropical fish (fish that naturally inhabits warmer climates), then you should maintain the right water warmth for the tank. Tropical fishes, for example, live in bodies of water with an average water temperature of 75 to 85 degrees Fahrenheit. If the natural habitat of the fish is in warm water, then you should have a heater to keep the fish tank warm.

The answer to whether or not you need a heater for your fish tank is not always obvious. But here are some factors that will help you identify the need for a heater for your tank.

The Temperature of the Water Source

The first consideration you have to make is the temperature of your water source. Tap water, for example, is normally cooler than the average air temperature because the insides of a plumbing system keep it cool.

So if you are using tap water as your primary water source, then you probably need a heater so your tropical fish can thrive. But again, the temperature of the water source is not the only factor of consideration.

The Temperature of the Room Environment

Perhaps the bigger factor that affects the temperature of the water in a fish tank is the temperature of the room. Even if the water in the tank is too cold, it can get warmer if the room temperature is warm. The opposite effect happens if the water is too warm but the room temperature is low.

So that means that the temperature of the water source will only affect the fish tank temporarily. Sooner or later, the water’s temperature will shift closer and closer to that of the room temperature.

In other words, if your room temperature is just right for the fish, you might even need a heater. But if your room temperature is too low, you will need a heater for the fish tank. The room temperature is affected by the weather, insulation, or some sort of a heater.

How Do I Know if My Aquarium Heater is Working?

how do i know if my aquarium heater is working?

If you have an aquarium heater, it is quite tricky to tell if it’s working just by dipping your finger into the water. Here’s how I check if my aquarium heater is working.

Check the Heater Light

Most fish tank heaters have a light that indicates that it is on. But some models have a weird body that partially covers the light when you are looking at it from certain angles. But if you are sure that the light does not turn on, that might indicate that the heater is broken.

Use a Thermometer

A more certain way to check if your fish tank heater works is by using a thermometer. Make sure that you measure the temperature before you turn on the heater. After turning on the heater, leave it in the water for a few minutes before measuring the water temperature again.

If there’s no difference in temperature, the heater must not be working.

Pro tip: make sure that the tank is not under direct sunlight. Sunlight may give you inaccurate temperature readings.

How to Keep a Fish Tank Warm Without a Heater

Even if the temperature of the water source and the environment are too cold for your fish, you don’t necessarily need a heater. Here are some ways to keep your fish tank warm even without a heater.

Fish Tank Lighting System

Did you know that light results in heat? Without too much into the physics of the subject, light basically causes atoms to vibrate and produce heat. The lighting in a fish tank can make the tank warmer.

If you have sufficient light in your fish tank that the water temperature is habitable for your fish, you will not need a heater. Another factor related to the tank’s lighting system is exposure to sunlight. Is your fish tank exposed to sunlight? Sunlight makes the water considerably warmer.

Fish Tank Cover

If your fish tank has a cover on top, there is very little heat escaping the tank, if any at all escape. This means that the water will be more consistent in retaining its warmth. Even if the room temperature is too low, a fish tank cover will help keep the warmth of the water consistent.

If the day temperature is warm enough for your fish, adding a cover on top of the tank keeps the warmth through the night.

Water Movement and Amount

Water that moves due to currents is better at retaining its temperature. Additionally, a larger body of water keeps its core temperature better than a smaller body of water. If you want to better maintain the warmth from the lighting system or the daytime room temperature, I suggest two things.

I suggest that you make the amount of water as large as possible. The other step you can take is installing some sort of device that adds a current to the water.


“Do I need a heater for my fish tank?” If you keep fishes that only live in warmer climates, you should maintain the proper water temperature for them. If you live in a colder climate, or the average room temperature is low, you need a heater. There are ways to keep a fish tank warm even without a heater. A good lighting system, an aquarium cover, or maintaining a current in the water helps keep the warmth of the tank.

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