Fish Tank Temperature Control – Tips To Keep It Constant

In this article, you’ll learn how to control your fish tank temperature and keep it in the ideal range for your species of fish.

Keeping a constant temperature in your aquarium is an important piece to a balanced and healthy aquarium.

Large fluctuations in temperature can stress your fish, make them susceptible to disease and infection, and impact your water quality.

Let’s get into it.


Control Your Temperature With These Heaters

What Temperature Should Your Fish Tank Be?

Most tropical fish tanks require a temperature between 75-80 degrees Fahrenheit (23-27 degrees Celsius). But the ideal temperature range really depends on the type of fish you plan on keeping. Even fish of the same species can prefer a much different temperature range.

We’ve provided a chart of some common temperature ranges for some popular fish species to help you along.

Common Freshwater Fish Tank Temperatures For Popular Species

As we just mentioned, every fish has a specific temperature they would consider to be ideal. It’s your job to ensure you keep your aquarium temperature constant and within range.

The good news most tropical fish you’ll find in your local fish store will require a very similar temperature, and in most cases, the range will overlap a little, so if you have a community tank, you’ll need to find that sweet spot for everyone.

You can use the chart below to help you along, but it’s just a general guideline. Make sure you look up the ideal temp range for your specific species of fish.

Tropical Fish Temperature Chart

Fish Species Temperature (Celsius)
Goldfish 68-74° F (20-23º C)
Tetras 75-80° F (23-27º C)
Guppies 72-78° F (22-25º C)
Barbs 68-79° F (20-26º C)
Betta 78-80° F (25-27º C)
Cichlids 78-82° F (25-28º C)

Further Reading: If you’re sick of reading the old complicated beginner guides then check out our guide: Best Freshwater Aquarium Setup. Check it out!

7 Tips To Keep Your Aquarium Temperature Constant

Depending on where you live and where you have the aquarium set up, controlling the temperature and keeping it constant and consistent can be challenging.

For example;

  • If your aquarium is in a basement in Canada in the middle of winter, you may struggle to keep it warm.
  • Or, if your aquarium is in the front living room in Sacramento on August 15, you might struggle to keep it cool.

Regardless of your situation, here are a few things that will help keep your aquarium temperature constant.

  1. Monitor the temperature with a thermometer: Even a small thermometer with a suction cup will work. There is really no reason to not have one.
  2. Get a good heater: Yup, you’ll need one, so get one.
  3. Install aquarium heater controller (regulator): Heater controllers not only monitor the water temperature, but they can adjust the heater so your tank maintains a very specific temperature range.
  4. Use a chiller: Specialized equipment for large cooling jobs or for multiple aquariums.
  5. Watch the water level: Less water means less control over temperature and more fluctuation. Be sure to top off any evaporated water every few days.
  6. Location is everything: don’t place your tank in front of a window or over a heating vent.
  7. Read product warranties: Always make sure your equipment is functioning correctly.

How To Lower Your Fish Tank Temperature If It’s Too Hot

There are many things you can do if your aquarium gets too hot. In addition to using some of the tips above, you can try this:

  1. Use an airstone or aerator to help keep the water moving. This will also help improve oxygenation and gas exchange at the surface, helping cool your aquarium.
  2. If you are using a lid, then open it or remove it altogether.
  3. You can complete a water change and add some water and add water that is the right temperature.
  4. You can use a bag of ice. Careful with this tip as it can lower the temperature quickly. Avoid dropping the temperature by more than 2-3 degrees Fahrenheit as this can shock your fish. Also, never place ice cubes directly into the water.
  5. Turn down your heater; don’t turn it off in case you forget about it.
    If you are using lighting other than LED, try turning off the lights. Some lighting like Metal Halide can quickly raise the temperature in your aquarium.
  6. Close your curtains. If your aquarium is in a room that might be getting a little sun, close the curtains during the day.
  7. Try purchasing a chiller. They can be expensive, and I would only recommend them if a hot aquarium is a regular issue for you or multiple aquariums.

Further Reading: Can a Fish Tank Heater Catch on Fire

How To Raise Your Fish Tank Temperature If It’s Too Cold

Many of the same tips above that are used can also be used to heat your aquarium.

  1. Turn your lights on.
  2. Turn your heater up
  3. Open your curtains if there is a window near.
  4. Do a water change and add slightly warmer water. Make sure you check the temperature of the water before adding it to your aquarium. Avoid raising the temperature by more than 2-3 degrees Fahrenheit as this can shock your fish.

How To Check Your Fish Tank Temperature Without A Thermometer?

To my knowledge, you really can’t tell the temperature without a thermometer.

You can always use your finger to see if it feels hotter or colder than usual or if it feels to be close to room temperature.

However, this might be relative to each person.

For example:

  • Someone outside in the chill of fall can place their hand in room temperature water, and it will feel warmer.
  • Someone who is out in the middle of summer might think the water feels a little cooler.

The best thing to do is to get a thermometer as soon as you can. In most cases, a small thermometer with a suction cup is usually less than $2 at most stores.

Good Luck!

Video: How to Maintain Aquarium Temperature

Jack Dempsey
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