Best Aquarium Thermometers Review

Best Aquarium Thermometers

Having the right temperature in the water is crucial to the healthy state of aquatic beings. Fish are particularly sensitive to changes in temperature. So as the owner of a fish aquarium, it is your duty to get the best aquarium thermometer for the sustenance of this aquatic life that you endorse at home or at the office.

You have to know more about these devices. Like everything else in the market, there are many types of thermometers you can find in the market in the current day. Learn about them, choose wisely before you make an investment. We will talk more in detail about this right here. Hang on to the stretch of your attention!

In a Hurry? Take a Look at Our Top 5 Picks of Best Aquarium Thermometers

ProductRatingCheck Price
Inkbird ITC-308 Digital4.5 Check on Amazon
Zacro LCD Digital4.4 Check on Amazon
American Thermal4.2 Check on Amazon
Keynice Digital Thermometer4.3 Check on Amazon
SUKRAGRAHA Traditional4.3 Check on Amazon

How Does an Aquarium Thermometer Work

There are two kinds of aquarium thermometers that you will find in the market. One works inside, and the other from the outside of the tank or bowl of water. The ones that are placed on the outside are called stick thermometers or LCD thermometers.

Since they detect the temperature of the water from the outside, they are sometimes a little off of the actual mark. The detection is done by liquid crystals packed into a plastic strip deep inside the thermometer. These crystals change color when there is a change in temperature.

LCDs usually last longer since they sit safely outside the tank. Then we have thermometers that work from inside the tank. There are two options here – standing thermometers and floating thermometers.

The number labels on a standing thermometer are small, but there is a very prominent mark that you can easily check from the outside to know whether the temperature is still within the safe limits, or not.

Floating thermometers are the same as the standing thermometers, with just one obvious difference between them – the floating ones float freely on water, whereas, the standing thermometers stand, fixed, in one position.


5 Best Aquarium Thermometers

Constant instantaneous accuracy is what you need from aquarium thermometers. We’ll show you some devices that come checks out on that criterion shortly. Keep reading, and read thoroughly to understand the obvious and subtle differences in some cases.


  1. Inkbird ITC-308 Digital

Inkbird ITC-308 Digital Temperature Controller Outletsmoker ThermostatThis is not as much a thermometer, as it is a temperature controller with very accurate skills in temperature detention. You can use this device both on heating and on cooling equipment. It comes pre-wired with all the necessary connections, and thus makes your work simpler.

The only thing you have to get this device going is to plug it in. All else will be done automatically. It will take a reading of the temperature of water from the outside, and based on those calibrations; it will then take some actions in order to stabilize the temperature to the desired setting.

So yes, you can select a certain temperature for it to maintain, and it will turn off the heating plug or keep it turned on as per necessity. The device really will save you a lot of time and worry in the long run. If, for some reason, the adjustment cannot be done, then an alarm will go off and let you know of the situation.

It will be able to take a maximum output load of 1100 watts under 10 volts. If you have ever faced bad experience with a thermostat before, and are skeptical about trying out new ones, we must tell you that this will definitely not be the case with this device.

In the worst-case scenario, the readings on display will just be about 1 degree off, and that will not make much of a difference on the aquatic life in your aquarium.

Highlighted Features:

  • Shows readings in both Fahrenheit and Celsius scales
  • You will be able to set a fixed temperature on the device
  • No hassle in setting things up since it’s a plug-and-use model
  • Has two temperature displays – one shows, and the other sets the reading

  1. Zacro LCD Digital Aquarium Thermometer

Zacro LCD Digital Aquarium ThermometerAs you can tell from the name, this one is an LCD thermometer. If you can remember from the section above, this thermometer is meant to stay outside the water. Yes, it’s a little hydrophobic. So to compensate for that, it has a temperature sensor probe that you have to place inside the water instead.

This probe has the detector, and the thermometer has the display that shows the reading. You can choose for the reading to show up in Celsius and also in Fahrenheit measures, according to personal convenience. Another aspect that works as a token of durability for this device is that it works with an LR44 battery.

If you don’t know what that is supposed to mean, we’ll tell you. These batteries are the most reliable and long-lasting among the many in the battery world. These are called button cell batteries, and they have alkaline 1.5-volt cells. The advantage of this is that they are not only of high quality; they are also rechargeable!

You will not have to replace these batteries, but just to recharge them when needed.

One thing to note about the readings that will show up on the LCD display is that they will have a deviation of 1 degree. This is only because the thermometer body is placed on the outside. The deviation itself will fortunately not have any big impact on the life inside the tank.


Highlighted features:

  • Very clear readings on the display
  • Shows very accurate readings in whichever unit you prefer
  • This device will last for many years as it will be in safety outside the tank
  • Can be used to take temperatures in any kind of water – fresh, tap, salty, marine

  1. American Thermal

American Thermal Aquarium ThermometerFinally, we have one of those fun, color-changing thermometers that make it easy even for a baby to tell whether the life inside the water tank is safe or in danger. This is a trusted device by a multitude of different aquarium-owners, and we definitely see why.

It is a very simple device; we will begin by saying that. You will need to place it on the load line or on the outside of the tank. Position it nicely, hold it in place, and just press on it firmly to have it cling on to the surface of its placement. As an alternative, you can also have it mounted on a flat position as the probe goes inside.

There is nothing fancy with this device. It comes cheap and works out its basic function in the most professional manner. The color-changing fluid inside the thermometer changes color in a very subtle and neat way with even the slightest changes in temperature.

One problem with this small dinky little device is that over time, it may happen to adjust to the temperature of the glass on which it is mounted. This will have damaging effects on the readings, as you can imagine. You will have to keep a close eye on it as time progresses in order to know when to go for a replacement.

Highlighted Features:

  • Very easy to position it on the required place
  • Shows the temperature variations very accurately
  • Has that interesting, color-changing feature as a means to the temperature detection

  1. Keynice Digital Thermometer

Keynice Digital ThermometerThese thermometers will not only be useful in aquariums, but they can also be used in cars, air ducts, and computer towers. So, even if you don’t have an aquarium any time in the future, you will be able to make proper use out of this device. It can detect all kinds of regular temperature changes in both the media of air and water.

The readings come on a digital display in units of Fahrenheit. As this is a digital thermometer, you will have to place it outside the tank, and therefore, the accuracy of the readings will naturally be a little off than with inline thermometers. Fortunately, however, they will not deviate any further than by a mark of 1 degree at any given point in time.

One good thing is that they will not lose the accuracy of their reading even with time. They are very long-lasting devices that you can rely on. You will have to mount them on the glass surface. Or, you could also flush mount them, and for that, you will need a mounting hole of about 1.83 x 1.08 inches in proportion.

A USB DC5V cable will come in the package, and it will not be required for you to get any extra attachment in order to get this device started. Finally, you will notice that the readings appear loud, colored, and clear on the digital display, which makes the device all the more convenient for busy fish owners.

Highlighted Features:

  • The required cable will come in the package
  • Can detect temperature changes very instantly
  • Readings come very clear on a big digital display
  • Can be mounted on a surface or also with the help of a hole on the wall

  1. SUKRAGRAHA Traditional

SUKRAGRAHA Traditional Stick-on Digital Temperature ThermometerFinally, we have one of those traditional thermometer designs that you had probably seen in your grandmother’s house when you were merely a child. To bring back those nostalgic memories, this company has designed an aquarium-wall thermometer. It will just sit vertically on a wall and do its thing.

It’s a stick-on thermometer that can be conveniently placed on any part of the glass aquarium surface with just a tight, firm press on the device. The readings on the device are a bit short in range than in other thermometers. They will show readings from about 14 to about 31 degrees if they are set to show up on the Celsius scale.

Besides this, you will also have the liberty to set up the scales in Fahrenheit, if that is what you prefer. Another matter of convenience is in the fact that these readings show up in discrete values. So it will be easier for you to judge the temperature changes more accurately.

The display will also give you colors – brown, the darker color, for higher temperatures, and blue, the vibrant color, for the regular water temperature. As time passes and you grow familiarity with the device, you will soon get accustomed to reading the colors from a distance, and eventually, you will not even have to look at the readings closely to know when something is not right.

Highlighted Features:

  • Can measure both in Celsius and in Fahrenheit scale
  • You will get ten pieces of adhesive strips in the package
  • Shows a different color each time the temperature fluctuates
  • Mounting this device on any glass surface will be very easy

What to Look for in an Aquarium Thermometer

Now that you have read the aquarium thermometer reviews, for more wisdom in your purchasing decisions and more confidence in the device you invest in, take a look at the different aspects of a good aquarium thermometer.

Ease of Installation

The more complex the system is, the pricier it will be. Many thermometers in the market have more fancy about them than is required. For regular house and office aquariums, a simple device would suffice, just as long as it has a good sensor in it.

Devices that are easy to install usually last longer than very complex ones. The price will also go unnecessarily higher on the complicated ones with no special change in performance. So opt for one that is easy to set up!

Range of Readings

Having a thermometer with a big and particular range of readings will be very beneficial for the health of your fish, and therefore, you should take this very seriously into thought. If your thermometer has a small range, it will not be able to show you readings that lie beyond it.

With the rise of global temperatures, these types of faulty small range thermometers will really become useless with time. So if you want to invest good money into a thermometer hoping for it to stay long with you, then go for one that has the capability to detect temperature changes over a wide range!

Accuracy of Readings

Life is not so fragile inside the water tank, to be honest. However, one problem that inaccurate readings cause is that one day you will look at your aquarium and see all the beings dead inside. We don’t usually stick our fingers inside the water to double-check the aquarium.

To avoid this, check the deviation range on the specifications on the package. If it is anything about a +/-1, we would advise you to keep away from it.


You must be able to tell what’s happening to the water in your aquarium even when you are not looking directly at it. Ease of readability will just make it more convenient for you to keep an eye on it. This also means that your thermometer must be able to show readings in both Celsius and Fahrenheit scales.

If your thermometer requires you to do math every time, then your investment in it is not worth your time. These readings are the most useful when they can be taken at a glance.

How To Use an Aquarium Thermometer

You have to install the thermometer inside or outside the tank as per instructions specified on the package. If your tank is of massive proportions, then you may have to use multiple thermometers. This depends on the size and the capacity of the thermometer you have gotten.

Any place that you put the thermometer to stick on must be clean. Wipe the area with a soft, damp cotton cloth. Then you have to pull off the adhesive tape carefully before you finally stick it on the surface of the glass.

If you are working with probes, then you have to keep the thermometer device on a flat surface outside the tank. Alternatively, you can also use flush mounting to put the device up on a convenient location on the wall. Make sure that the place where you are keeping the thermometer is safe and easily noticeable.

The most important function of the thermometer is for it to give accurate readings. Readings may be shown in both Celsius and the Fahrenheit scale. If you can choose, then look at the settings and see which button is showing you the unit. Press that button to change the setting!

You will be provided with a chart that shows what you have to do in correspondence to the readings. Keep that chart around and consult it while taking readings. Many displays show color-coded readings. In that case, too, you will have a chart telling you what each color means.

That is all there is to use a thermometer.



We are going to try and clear up any confusion that you may have after reading this article. Hope we can address all your queries all by ourselves. If you still have any bit of data missing, let us know in the comments!

      1. What materials go into the making of thermometers?

Most thermometers are made of glass. Inside, the temperature detector is liquid Mercury.

      2. Is a Mercury filling safe for the fish?

No, Mercury is a toxic substance, and the results of being exposed to Mercury would be fatal to the fish in the tank. If the thermometer breaks at any point in time, make sure that you immediately evacuate the fish and give them several changes of water baths to clean them.

Clean the entire tank as well, and then refill with fresh water before putting the fish back in.

      3. How do I know if the readings that my thermometer is showing are accurate?

Do the ice glass test! Put some ice into a glass, and then stir the ice for about 15 seconds. After that, put the thermometer, or its probe inside and check. If the reading is about 32 Fahrenheit, then it will mean that your thermometer is going to show readings in the correct range.

      4. Do I need to use more than one thermometer for an average house aquarium?

Not necessarily. But it will be wise to keep one extra in hand. You never know when a heavy fish might bump into the inline device you have, and cause it to break.

      5. Why is it so important to maintain the temperature inside the tank?

Water that is too hot will not be able to carry the adequate amount of oxygen for the fish to breathe in. On the other hand, water that is too cold will make the fish lethargic and prone to starvation. Temperature control is very important for the healthy development of fish and any other aquatic beings you may be petting.


Final Thoughts

Having fish as pets is really not that much of a hassle. However, you have to make sure that you are maintaining the temperature and keeping the water clean, as these two components are key to the making or breaking of the health of your fish. Just get the best aquarium thermometer that you can find, and you will be golden for days without bothering with them unnecessarily.

Good luck with your fish keeping skills!