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The 9 Best Aquarium Thermometers

A small but important component of any aquarium setup. A comfortable temperature range exists for all known life forms.

This temperature range can be important for wild fish, plants, and corals.

Weather and seasons can have a significant impact on the temperatures of tropical coral reefs and freshwater rivers.

However, any experienced aquarist will tell you that monitoring your aquarium's water temperature is crucial, as even a small fluctuation can be catastrophic.

There are many types of aquarium thermometers on the market, just like other aquarium equipment.

It can be a challenge to choose the ideal thermometer for your needs, as is the case with many similar devices.

To assist you, BestForPets (bestforpets.org) has compiled the following reviews of the best aquarium thermometers on the market.

Instruction Manual

Several factors should be taken into account before settling on a certain aquarium thermometer.

Simplicity of usage

As obvious as it may sound, aquarium thermometers are only useful for one thing: letting you know how hot or cold the water is in your aquarium.

They don’t have to be hard to install or use to serve this purpose. One of the most important criteria in picking which thermometer to buy is how simple it is to use.

That’s not to imply the simplest thermometer is the best, but it does mean you should include in the device’s ease of use while making your decision.


One of the most crucial aspects of a good aquarium thermometer is its precision. After all, keeping an eye on the temperature of the water in your tank is useless if you aren’t confident in the accuracy of the readings.

In general, digital thermometers that display data on an LCD screen are the most reliable. Additionally, they remove the person as the single most influential source of error in thermometer readings.

It’s easy to misread the temperature when using a classic mercury-in-glass thermometer, but not so when using a digital one with an LCD display.


It should go without saying that you should only get a thermometer that can accurately measure temperatures in the range you intend to monitor.

Most aquariums just need to be between 50 and 104 degrees Fahrenheit (10 and 40 degrees Celsius).


Although thermometers are not very pricey tools, you should still choose one that will last you for quite some time.

A mercury-in-glass thermometer may seem like an inexpensive addition to your aquarium, but the last thing you want is for it to fall off the edge of the tank, break, and release mercury into the water.

The same holds true for a digital thermometer, namely one with an LCD display, if it doesn’t operate correctly or if it breaks down soon.

The conclusion here is that you need to invest in a high-quality thermometer that is appropriate for your aquarium.

Thermometer Type

Aquarium thermometers may be divided into three categories. Each has a unique mounting and function, so choosing the right one for your aquarium will rely on a number of factors.

Adhesive temperature gauges

This sort of thermometer, as the name implies, is meant to be affixed to the exterior of the container. The range of temperatures is presented longitudinally, with the current water temperature in the foreground.

An infrared thermometer’s pros include its low price and user-friendliness. Some doubts have been raised regarding the precision, and it is unclear how factors such as the thickness of the tanks and the air conditioning in the space surrounding the tanks affect the results.

Although the thermometer may be off by a few degrees, in practice this is not a major concern unless the room temperature is significantly lower than the water temperature.

Thermometers That Can Float or Stand Up

Most thermometers used inside of tanks are the mercury-in-glass kind, which floats or stands upright. They are more accurate than stick-on thermometers at determining the temperature of the water being used.

They may be suctioned to the interior of the tank glass or hung over the edge of the tank.

One major drawback is that this sort of thermometer is typically constructed of glass, making it vulnerable to being bumped by large fish or blown off fittings by the current from a wavemaker or circulation pump.

Yet another drawback is that their scales are typically rather tiny, making them hard to read from a distance.

Infrared thermometers

You may take the aquarium’s temperature using a digital thermometer by submerging the probe into the water. The probe can be left in the tank permanently or temporarily, depending on how the thermometer is being used.

After that, a connection is run from the probe to the screen displaying the digital data.

Most of these gadgets run on batteries, but there are a few that can be powered by electricity.

The major benefit of this form of thermometer, aside from its accuracy and simplicity, is that models are made to be left on and in use at all times.

One common feature is an alarm that may be set to go off if the tank’s water temperature drops below or climbs beyond a certain threshold.


An accurate thermometer is an absolute must if you care about the health of your aquarium inhabitants and want to keep the water at a steady temperature (or within the temperature range you’ve set).

A review by BestForPets (bestforpets.org), along with the information in our buying guide, will help you decide which is the best aquarium thermometers for your needs.

We can confidently say that any tested thermometer will serve its intended purpose. Of course, not all are created equal. Our top picks are, again,


The Highest-Quality HDE LCD Digital Aquarium Thermometer Available

HCE’s digital thermometer is excellent because of its large, clear display. It’s easy to set up, and we appreciate how a suction cup is included into the probe’s wire to keep it firmly connected to the interior of your tank.

The digital reading is precise to within 0.1 degrees Fahrenheit or Celsius, can display temperatures in both Fahrenheit and Celsius, and has a very wide temperature range.

We recommend the HDE LCD Digital Aquarium Thermometer because it is accurate, easy to use, and inexpensive.


  • Major electronic screen
  • Extremely precise results
  • Price
  • Easily implemented and operated


  • Battery-powered


An Affordable Floating Thermometer for the Marina

Marina’s suction-cup-mounted, mercury-in-glass floating thermometer provides a reliable gauge of water temperature. The scale’s green “safe zone” color and clearly indicated markings make this 4.25-inch tall tool user-friendly.

This aquarium thermometer is the best of its kind if you need a simple tool for measuring water temperature. It is reasonably priced while still being of high quality.

Due to these reasons, we think it’s the finest aquarium thermometer available at this price.


  • Price
  • Well-built


  • Standard layout
  • 0 supplementary options


The Best Fish Tank Thermometer by JW Pet Company

The JW Pet Company Aquarium Thermometer is an option for those who want the finest for their aquarium.

There’s no need to worry about your fish or the flow of water dislodging this huge in-tank thermometer because it’s magnetized to the tank’s side. It’s sturdy and convenient thanks to the display’s clear text and green “safe zone” delineations.

The thermometer’s straightforward mercury-in-glass construction eliminates the need for frequent adjustments or battery replacements. A reliable indicator of temperature, this device never has to be turned on.


  • Produce a solid product
  • A magnetic clasp
  • Clear and legible screen


  • Price


Aquarium Temperature Gauge with LCD Display by Zacro

Upon first glance, the Zacro digital aquarium thermometer may seem quite similar to the Marina gadget, which we have deemed the finest overall thermometer.

The suction cup mounter probe, huge digital readout in both Fahrenheit and Celsius, and broad temperature range are all features that can be found on both thermometers.

However, there are a few key distinctions that have led us to rank this gadget somewhat lower than others on our list.

The most immediately noticeable distinction is the higher cost of this variant. And secondly, it’s only accurate to within one degree, which is a lot less precise than Marina’s equipment.


  • Detailed electronic screen
  • The setup and operation are a breeze.


  • Price
  • Battery-powered


The Digital Aquarium Thermometer from AQUANEAT

With the exception of a slightly bigger suction cup to keep the probe in place, the AQUANEAT Aquarium Digital Thermometer is identical to the Zacro gadget described above.

The same high quality construction, wide temperature range, and user-friendly digital display are present. When compared to the Zacro gadget, there isn’t much of a price difference.


  • Extensive electronic screen
  • Fast and simple set-up and operation


  • Price
  • Battery-powered


The LCR Hallcrest A-1005 is a Vertical Aquarium Thermometer

LCR Hallcrest’s vertical aquarium thermometer is a popular model thanks to its stick-on LCD design and tank-mounted placement.

This form of thermometer, which is not submerged in the water, is often highly accurate unless the tank has very thick glass walls or the air temperature outside the tank is significantly colder than the water temperature.

If that’s the case, it’s possible that the temperature is wrong by a few degrees.

However, it’s quite simple to set up and use, and it doesn’t cost too much.


  • Simple to set up and utilize
  • Price


  • Not recommended for use with heavy glass tanks


Digital Aquarium Thermometer with LCD Display by VIVOSUN

Similar to the Zacro model we just evaluated, this is another another digital thermometer. A similar probe is secured in the tank and wired to the main unit to carry out the same function.

An easy-to-read digital screen is featured. The tank’s temperature may be shown in either Fahrenheit or Celsius, depending on your preference. This device is simple to set up and use, and it even includes the battery you’ll need.


  • In-depth electronic screen
  • Simple to set up and utilize


  • Price
  • Battery-powered


Nano-Temperature Thermometer from Fluval

The Fluval Nano is a mercury-in-glass thermometer that may be adhered to the interior of your aquarium’s wall.

While the thermometer’s readings are accurate, the instrument’s design leaves much to be desired; the instrument’s naked glass thermometer is not encased in a frame or otherwise protected.

As long as it stays securely placed within your tank, you should be good to go. However, it is easily broken and may leak mercury into your tank if it falls or is hit by a large fish.


  • Simple structure
  • Simple to set up


  • Tiny, difficult-to-read scale
  • No warning signs of a safe area
  • Danger of breaking easily


The AQ150 Indoor/Outdoor Aquarium Thermometer from General Tools

This digital thermometer from General Tools might be a great option if you’re searching for a model with plenty of extra features.

When set up, the digital thermometer is functionally equivalent to the other devices we have studied; a probe is put into the tank and the unit’s main unit receives readings via cable.

The General Tools gadget boasts a bright, easy-to-read screen that can be used in low-light situations with the press of a button.

In contrast to similar products we’ve examined, this one features an audible alarm that goes off if the temperature of the water in your tank increases or falls outside of a certain range.

This digital thermometer has the most features, but it also has the highest price tag of the products we’ve looked at.


  • Extensive electronic screen
  • Simple to set up and operate
  • Warn about rising temperatures


  • Price
  • Battery-powered

Author Image

Dr. Barry Buttler

Dr. Barry Buttler, DVM, MS, DACVIM, is an experienced veterinarian who specializes in the care of small animals, specifically dogs. Dr. Barry K. Buttler is a member of the American Veterinary Medical Association and holds multiple certifications in small animal emergency medicine and geriatric pet health.

Veterinarian (DVM) Dr. Barry Buttler


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