5 Best Aquarium Thermometers

It doesn’t matter whether you’re a beginner when it comes to setting up and maintaining an aquarium, or you’ve been doing it for decades and know your way around a flow pump and substrates, you’ll know the importance that water temperature plays in keeping fish.

Even a fish tank that differs a couple of degrees in either direction can have catastrophic consequences for the fish and the plant life inside, even if it’s temporary. This is why it’s so important to manage and monitor the temperature yourself.

With this in mind, what better way is there to manage the temperature than purchasing and using a thermometer. While this is a great idea, you’re going to need an accurate thermometer that’s designed to be as precise as possible, ensuring you’re able to pinpoint the nearest degree and take appropriate action.

Today, we’ve taken all the hard work out of choosing the right, reliable thermometer and done it all for you. After much deliberation, we’ve narrowed down what’s out there to just five of the best thermometer devices, and then detailed everything you need to know in order to choose the one that’s right for you.

Aquatix Pro Aquarium Thermometer 3PC Set

Aquatix Pro Aquarium Thermometer 3PC Set

To start off our list, we’ve chosen the outstanding Aquatix Pro 3-piece Thermometer set. Off the cuff, this means you have access to everything you need in order to take the most accurate reading of your water temperature.

What we love about this set is the fact it comes with two digital thermometers, and then your standard mercury thermometer. This means there’s absolutely no reason to second-guess your readings, and you can check both ways to make sure it’s completely accurate.

Starting with the digital readers, both display the temperature it reads through the probe only in both Fahrenheit and Celsius, and each probe even comes with a suction cup, so you can fix it to the same spot in your tank.

While you need to bear in mind that the thermometer itself isn’t actually waterproof, the fact you have both is a great way to test the temperature of the water in different areas and depths of your tank; ideal for giving you an all-around reading.

The mercury thermometer also comes with a suction cup and is fully submersible, so you can set it up wherever you want. Each type of thermometer has a great operational range, and if it doesn’t perform of you’re in any way unhappy with your purchase, which we’re sure you won’t be, you can get a full refund with no questions asked.

  • Comes with two digital thermometers and one mercury
  • Each thermometer and probe have suction cups for easy mounting within your tank
  • Capable of reading in both Fahrenheit and Celsius
  • Comes with a pre-installed battery and a long lifespan
  • Digital displays aren’t waterproof, only the probes are

LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer

LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer

We really like the LCR Hallcrest thermometer, simply due to the fact that it’s designed to be like the
original thermometers that all older fish tanks had, and most experienced aquarium owners, especially those who have been doing it for over a decade now, will remember.

These old-school thermometers are great because you can simply mount them onto the side of your aquarium, wherever you want that to be, and you’ll be able to read the temperature in real-time no problem.

The thermometer is incredibly easy to read thanks to its color-coordinated design, and you can even move it as many times as you want without this causing a problem to your tank, or the thermometer itself.

Of course, these thermometers do have the downside of not being as accurate as a digital thermometer, and they require a little bit of time to adjust when you move them for the most reliable reading, but for the price and the effectiveness, it doesn’t get much better than this.

There’s no need ever to change the battery (because there isn’t any), so you can simply leave this hanging up on the side and just remember to look it at whenever you’re passing to make sure your aquarium is doing well!

  • Color-coordinated design for easily identifying the temperature of your tank
  • Doesn’t require batteries to operate
  • Can be stuck and moved around your tank as many times as you want
  • Broad temperature reading in Fahrenheit
  • Not as accurate or as quick as digital thermometers
  • Doesn’t display temperature in Celsius

HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control

HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control

Heading back over to digital thermometers, this time opting for the HDE Digital Water Temperature Control Thermometer; an affordable solution that comes with no frills but is designed to give you the accurate information you need to keep your aquarium tank in check.

This model comes with a large, easy to read display that you can look at as you walk past your tank. The thermometer itself cannot be submerged into the tank, but the probe can be. However, the LCD display can be suction-cupped to the outside of the tank, so it easily stays in position.

What we love about this digital thermometer, in addition to the amazingly affordable price tag, is the fact that’s accurate within 0.1 of a degree and can operate everywhere between 50 and 70°C. Fortunately, Fahrenheit and Celsius’s readings are supported.

Everything you need to use this thermometer is included, even the batteries are, so it’s ready to go straight out the box and there’s no need to buy anything extra or additionally.

While this particular model doesn’t come with a high/ low-temperature alarm, for the price, there’s no better digital thermometer out there!

  • Displays readings on a large LCD digital screen
  • Readings are accurate within 0.1 of a degree
  • Displays temperature in both Celsius and Fahrenheit
  • Comes with everything you need straight out of the box
  • Doesn’t have a high/ low-temperature alarm
  • The temperature display isn’t waterproof

RISEPRO Aquarium Thermometer (2-Pack)

RISEPRO Aquarium Thermometer (2-Pack)

Another fantastic digital thermometer set is the one manufactured and supplied by RISEPRO. This is easily one of the most popular and highly-rated thermometer sets on the market, and it’s ridiculous that you can acquire two of these quality thermometers for the price of one.

What sets these thermometers apart from the rest of the market is their outstanding range. While you’re probably not going to need all of it, these devices can range from -50°C all the way up to 70°C, which is more than enough. With an accuracy reading of 1°, you’re always going to know the condition of your aquarium.

Thanks to the versatile design of this set, you’ll be able to use them in all kinds of tank environment, including both salt and freshwater tanks, and even temperature keeping for other animals, such as lizards and reptiles. The fact you get two thermometers means you can use them for both on a single purchase!

Of course, these thermometers are really simple to use thanks to their user-friendly design; large LED display, and the ability to simply toggle between Fahrenheit and Celsius using the dedicated toggle.

Everything, including the batteries, is included, and with an estimated 9-month battery life while being left on 24/7, what more could you ask for?

  • Impressive 9-month battery life if you never turn them off
  • Two digital thermometers per purchase
  • Readings are accurate within 1°
  • Impressive reading ranging of over 80°C
  • No backlit on the digital displays

Zacro LCD Digital Aquarium Thermometer Fish Tank Temperature Control

Zacro LCD Digital Aquarium Thermometer Fish Tank Temperature Control

The final accurate aquarium thermometer we’ve chosen for our best-of list is a real winner, and easily the highest rated digital thermometer of its kind, as well as holding the title as being the most affordable thermometer on our list.

While there is only one thermometer per pack, this one comes with a large LED screen for easily reading the temperature of your tank while minimizing the risk of misreading the digits. There’s an impressive reading range of -50° up to 70°C, and readings can be read in both Fahrenheit and Celsius.

Whether you want to set up your thermometer to read the temperature all the time, or you just want to take readings here and there, this thermometer has got you covered. The main temperature-reading probe will simply hang in the water wherever you want it to go, while the screen part can be attached to the outside of your tank using the suction cup.

Both the batteries and cables are included with your purchase meaning there are no additional investments to be made, and with an accuracy of +/- 1°C, you can’t go wrong with this thermometer.

  • Dedicated Celsius/Fahrenheit toggle
  • Accurate readings within 1°C
  • Mount your display anywhere using the suction cup
  • Outstanding operational temperature range
  • Only comes with one thermometer per pack
  • No high/ low-temperature alarm


While the importance of water temperature can never be understated when it comes to keeping an aquarium, this list proves that the solution for monitoring this vital aspect is easy. There are plenty of highly accurate thermometers out there, some of the best of which are listed above.

All you need to do is pick the one that’s right for you and your aquarium fish tank!