5 Best Digital Thermometers For Your Aquarium | iPetCompanion

5 Best Digital Thermometers For Your Aquarium

Freshwater and tropical fish can't survive if the water is not within a certain temperature range. Your fish will become sluggish in a cold aquarium and they won't want to eat. You can try many ways to achieve that optimal temperature, like an aquarium heater would do the trick. The problem is that you need to ensure that the desired temperature has been achieved, and that's when you can resort to the best aquarium thermometer. 

Here are some of the best options to help you choose the right digital aquarium thermometer.

JW Pet Company SmartTemp Thermometer

Best Standing Thermometer

  • Magnet for easy placement
  • Easy to clean

Rated by: Amber

RISEPRO Digital Water Thermometer

Best Overall

  • Good battery
  • Clear display
  • Compact size

Rated by: Amber

LRC Hillcrest A-1005 Thermometer

Best for simplicity

  • Easy to use
  • Clear display
  • Easy placement

Rated by: Amber

The Best Aquarium Thermometer: Our Top Picks

1. JW Pet Company SmartTemp Thermometer

Quick Summary

Rated by: Amber

This aquarium thermometer will offer a good bang for the buck because it is highly active and lasts for a long time. It is extremely easy to use it because unlike many other thermometers that use a suction cup, it relies on a magnet to stick to the walls of the aquarium.  Thanks to the magnet, you can move the thermometer around with the utmost ease.

It is easy to clean it as well, and that is also because it doesn't use a suction cup that tends to have a buildup forming around it. You can move the thermometer to clean it whenever you want. It also works effectively and is quite easy to read as well. That's mainly because the numbers are quite large.

It may not be a great choice for a large aquarium, but it serves as a highly effective option for a beginner thank. The only downside of buying this thermometer is that it is easily breakable, but that's something you have to bear with when you buy a glass thermometer.


  • It comes with a magnet for easy placement
  • It is easy to read with large numbers
  • It is easy to clean and maintain


  • It breaks easily

2. RISEPRO Digital Water Thermometer

Quick Summary

Rated by: Amber

If you're looking for a highly accurate temperature and are not that concerned about the price, you should go for this particular model. It gives accurate reading irrespective of the type and size of your tank. The temperature range is from -58F to 158F – it shows reading in both Fahrenheit and Celsius.

Unlike many other digital thermometers, it has a good battery time and continues to serve you well for long. In fact, there are some reviewers suggesting that the thermometer keeps functioning well for a couple of years on the same battery. The good thing is that the package includes an additional LL4 battery, so you can replace whenever you want.

You won't face any issue when you want to read the temperature because the display is large and quite clear as well. The placement is easy, as the thermometer enjoys a slim and compact profile. You can put it anywhere and it won't hinder the view of the fish.

Overall, it's one of the best digital aquarium thermometers available on the market, but the only small complaint some users have is about the suction cup losing its grip after continuous use.


  • It has a long-lasting battery
  • It has a large and clear display
  • It has a compact size


  • The quality of the suction cup could've been better

3. LRC Hillcrest A-1005 Thermometer

Quick Summary

Rated by: Amber

In case you're after the cheapest way to monitor water temperature, you may want to put your money on the A-1005. It is a good choice because you don't need any experience installing it. You just need to stick it to the aquarium surface and it will start working.

The temperature is easy to read because the LCD is clear and crisp. It uses a crystal color system with the color green indicating the current temperature. The green turns brown suggesting that the temperature is slightly above the current temperature. If the temperature is lower than the current temperature, it will turn blue.

Overall, it's a good choice for basic aquarium set ups, but you should bear in mind that it is not as accurate as high-end digital thermometers. At the same time, some users have complained about the stickiness of the thermometer.


  • It is easy to use
  • It can be placed anywhere outside the tank
  • It has a clear display to read the temperature


  • It may be a bit inaccurate

4. Cooper-Atkins Waterproof Digital Thermometer

Quick Summary

Rated by: Amber

The simplicity of this digital aquarium thermometer will impress you the most. Setting it up will never be an issue. It comes with a reduced tip, so using it is even easier now. You just need to place the tip in the aquarium and turn it on to get the temperature reading. You get the reading in less than six seconds, which is something quite impressive.

Some users believe that it is not a specialist fish aquarium thermometer, but the truth is that its splash-proof design makes it suitable for the tank as well. It means you don't need to worry even if it accidentally drops into the aquarium. It also works great for most aquariums because the temperature range is between -40F and 450F.

It relies on a battery to work, but you will find batteries in the package. The batteries stay good for over 500 hours in most cases. It means the thermometer will work on the same batteries for years. It has a built-in mechanism to reserve battery life – it turns off after 10 minutes idle, which is a great feature for sure.

 It's a high-end digital thermometer, so you don't need to calibrate it for accuracy, as it continues to produce accurate reading without issue. It also comes with a customizable alarm, so you don't need to worry too much about drastic changes in temperature. The only issue is its high price tag.


  • It is very accurate
  • It comes with a customizable alarm
  • It produces results quickly


  • It's a bit expensive

5. Fluval Wireless Digital Thermometer

Quick Summary

Rated by: Amber

It's a 2-in-1 digital thermometer and works efficiently. You need to place it on the outer surface of your fish tank to get temperature readings. Using it is a breeze, and that's why it's a popular choice for basic tank setups.

It produce readings constantly, so you can keep an eye on how things are in your fish tank. It also helps you know if the heater is functioning properly and there aren't any drastic shifts in temperatures.  You can also switch between two modes for Fahrenheit and Celsius readings.  The display is also large and crisp.

The main consideration is its accuracy. While it is not way off the mark, you should still expect some discrepancies in readings. That's pretty common with thermometers that stick outside of the fish tank because the room temperature can cause interference.

 It doesn't come with a probe or something, which is why temperature readings aren't always correct.  It won't be a big issue though if you don't have fish that require precise temperatures.


  • It shows readings in Fahrenheit and Centigrade
  • It has a large display
  • It works for both saltwater and freshwater tanks


  • It may be a little inaccurate

FAQ - A Buyer's Guide

What is the Most Accurate Aquarium Thermometer?

In order to find the most accurate aquarium thermometer, you need to educate yourself about different types of aquarium thermometers available in the market. For instance:

You can find stick-on thermometers for your aquariums. Also called LCD thermometers, they're usually the most cost-effective options to consider. In fact, you will find them included in most aquarium kits. They come with a stick on the back that you need to attach to the outer surface of your aquarium. It usually comes with both Celsius and Fahrenheit scale, and are available in vertical and horizontal varieties.  They're cost-effective, but they may not be the most accurate options because they stay outside the tank, so the outer temperature may interfere with the reading.  Another downside is that they won't last that long and you may have to look for a replacement within a year of use.  Nevertheless, you can opt for these for a basic tank set up because they're cheap, easy to install, and harder to break.

A standing aquarium thermometer is another good option to consider, and it is quite accurate because you will have to place it inside the tank. They feature clips or suction cups that will help you place them on the aquarium glass.  Even though they're quite accurate, they're extremely easy to break, especially when you have rough or aggressive fish in the tank. 

A floating thermometer is also available these days, and again, it's relatively accurate because it stays inside of the tank.  It's actually quite like the standing thermometer, but the only difference is the way it is installed and used. You can also find some floating thermometers with anchors, so you can use them to keep the aquarium thermometer in one place and close to the bottom of the tank. The downside is that they're easily breakable and are often quite hard to read. They may cause other problems, especially when they float and block the filter.

A digital fish tank thermometer is also available, and though it may look a bit like lcd display thermometers, they're different. You will have to attach them on the outside of your aquarium using Velcro or suction cups. It also comes with a problem that you need to place in the tank using a suction cup. Even though they're the most expensive aquarium thermometer options, they're probably the most accurate too. Moreover, they are easier to read and maintain. It comes with a warning feature and turns the alarm on if the water gets too cold or too hot. Keep in mind that you will have to plug it into an electric outlet or use a battery to make it work.

The fact of the matter is that most thermometers deliver a satisfactory performance, but what works for you depends on your own budget constraint as well as the size of your tank. Nevertheless, a digital thermometer from a reputable brand is the most accurate option, if you're willing to cough up some money.

Where Should the Thermometer be Placed in a Fish Tank?

Depending on the type of thermometer you use, you will have to change the way you try to place it in your fish tank. In fact, some thermometers may not even go in the tank but stay outside of it. That is true for a stick-on thermometer, which you can place on the back, front, or side of the aquarium. Even with this thermometer, you should ensure you don't place it in direct sunlight – and keep it away from a heating or cooling unit or you won't get accurate readings.

In case you're opting for a standing or floating aquarium thermometer, it will be a good idea to keep it above the gravel line to get an accurate reading. You can also place these thermometers on the opposite side of the heater to ensure the heater doesn't interfere with the reading. Placing your thermometer away from the heater will also ensure a more uniform temperature throughout the tank.  All you have to do is use the suction cup on these thermometers to attach them to the glass.

In case of a floating thermometer, you can also place it halfway up the glass. This is to ensure that it stays within your line of sight. Be sure to pick a place where the thermometer is easy to read but it doesn't block the view of the fish.

Other than the types of aquarium thermometers, you need to consider your overall aquarium setup to select and place the thermometer in an appropriate fashion. So, be sure to take your time and decide what is suitable considering your tank size before making a purchase.

Do I Need a Thermometer for My Fish Tank?

If you're going to install a heater in your fish tank, it always makes sense to invest in a thermometer as well. And, you will always need a heater because your fish won't be able to survive if the water is too cold.

Understand that your tap water might be around 55F, which is a bit too cold for most fish.  For instance, Goldfish require a temperature of 68-72F to survive, whereas shrimp prefer 72F. Betta fish would thrive when the temperature is around 78F, and the same is the case for Tetras and most saltwater tropical fish. For your coral aquarium, you might need to keep the temperature around 80F.

Even if you have a heater, you won't have a clue if the desired temperature to keep your fish happy has already been achieved. You can also use the thermometer to check the temperature of the clean water when adding it to the tank – this way, you will be able to avoid shocking your fish.  Therefore, finding the best aquarium thermometer is crucial, and you should also check it at least once a day to ensure everything is fine.

By keeping a thermometer, you will be able to ensure a stable temperature throughout the tank. What it means that achieving the right temperature is important but keeping it stable is even critical for the wellbeing of your fish. Fluctuations in aquarium temperature, for instance between day and night can cause a sheer amount of stress to your aquarium inhabitants. It is only going to make your fish sick and lead to diseases like fin rot. By using the thermometer, you can identify any temperature inconsistencies and fix them early.

Moreover, a good quality thermometer will also help you figure if the heater is failing. Very cold water can kill your fish quickly, and your thermometer can inform you about these drastic temperature changes to take quick actions.

All this implies that investing in a good quality thermometer, which is sturdy and accurate, is important. It ensures that the temperature inside the tank is stable and that the fish have the right environment to thrive.

Are Sticker Thermometer Accurate?

Sticker or stick-on thermometers are common, and quite popular among new hobbyists with a basic aquarium setup.  They're mainly LCD display thermometers with their display changing color with a change in the temperature of your aquarium. They're quite convenient to use, as all you have to do is peel the sticker and place it on the outside of the tank. Now, the important thing to understand is that though a sticker thermometer is easy to use and cheap, it is not accurate.

Sticker thermometers rely on temperature sensitive ink that reacts to a change in temperature. The problem is that you can't place them inside the water. When they stay outside of the tank, it is natural for them to react to other factors. For instance, a change in the room temperature will lead to a higher change in the reading of the thermometer than the change in the water temperature. Similarly, if your aquarium is close to a heating unit, the sticker thermometer is going to react and display inaccurate reading.

The size of you aquarium and overall setup will also have an impact on the accuracy of sticker thermometers. For instance, you should expect a greater degree of inaccuracy if you attach it to a larger tank. The same holds true for an aquarium with a thick glass. 

Using a sticker thermometer may not be a great choice in terms of durability either, as most of them won't last a year. Yes, they're easy to apply and inexpensive, but what's the point in spending money when they can't show accurate readings. If you need a good alternative, you will be much better off using a digital thermometer that goes inside the tank.

A digital thermometer is a much better option, especially if you choose a reputable brand. Still, it is a good idea to check its accuracy first. You can do it by placing the thermometer in a glass filled with ice. Stir the thermometer for about 15 seconds and then check the reading. The thermometer is accurate if it reads 32F.

Most digital thermometers are expensive, but they work amazingly well. Not only are they very accurate, they also come with interesting features. For instance, you can find a high-end digital aquarium thermometer that works as a remote as well. It means you need to place them in the tank and they display the temperature on a display unit you can place anywhere in the home. In fact, you can have that temperature reading displayed in multiple locations to ensure everything is going smooth inside of your fish tank.

So, take your time and decide what you want to buy. With thermometer, accuracy is important, and that's why you will be better off making a higher upfront investment to buy a digital thermometer than cutting corners and buying a cheap sticker thermometer.

The Best Aquarium Thermometer to Buy

No one can deny the importance of maintaining a stable temperature inside of the fish tank to keep them active and healthy, and you have to use a good thermometer to maintain that stability. With so many different types available, it is natural to feel confused, but a good quality digital aquarium thermometer will always do, and that's when you can try RISEPRO Digital Water Thermometer because of its impressive battery, easy placement, and extremely accurate readings.

About the Author Steven

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