best aquarium thermometer

Best Aquarium Thermometer | 2022 Reviews

As an aquarium owner, you know the importance of keeping the right temperature to keep your aquarium environment stable and healthy.

Temperature swings are not good. It keeps your fish in a state of stress. To keep this from happening, it is important to monitor the water temperature constantly.

The best way to do this is to install an aquarium thermometer.

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Best Aquarium Thermometer Reviews

Capetsma Digital Fish Tank Thermometer

The Capetsma digital fish tank thermometer is unlike any other digital aquarium thermometer. For one, it does not come with a probe that you put in the water, which most digital thermometers are equipped with. No probe means no wires.

The Capetsma Digital fish tank thermometer is a stick-on digital thermometer with a sensor in the back that sticks to the aquarium wall. This sensor captures the temperature of the water accurately.

Its large LCD display on a transparent touch screen makes it easy to read and does not obstruct the aquarium’s view. You need to press “up” or “down” to switch degrees Celsius to degrees Fahrenheit, and vice versa.

Touch to set high-temperature warning and low-temperature warning. It has an alarm system that goes off if your current temperature is higher than the highest temp you set or lower than the lowest temp you set.

This digital aquarium thermometer is very easy to operate. Below the screen is a black battery cover, which you have to pull down to insert the battery. Then peel and stick the thermometer to the aquarium wall, and you are good to go.

The Capetsma digital fish tank thermometer is one great digital thermometer without messy wires. This makes your tank unique and beautiful.


  • Attaches to the outside of the tank, so you do not have to worry about cleaning it
  • Easy to operate
  • It has a high-temperature and low-temperature alarm warning system
  • An extra battery is included


  • It is a large size and takes up space on smaller tanks
  • It reads the water temperature through the glass, and there are no sensors placed in the water 

Zacro LCD Digital Aquarium Thermometer

The Zacro LCD digital digital aquarium thermometer has an LCD screen and a submersible probe for measuring the water temperature.

You can set temperature in both degrees Celsius and Fahrenheit, whatever your preference is.

Although the device is small, it has a very clear LCD display that you can easily read.

You can safely use this device in freshwater, saltwater, and brackish water tanks with just 1 degree of variance in accuracy.

It comes with a suction cup to mount your aquarium thermometer. Just make sure that it is placed out of sunlight, away from the heater, and above the gravel. The water temp probe is placed below the water level.

This product includes an LR44 battery, so there is no need for power wires. This battery is long-lasting and easy to replace.

For a budget-friendly thermometer, the Zacro digital is one very durable and accurate digital thermometer.


  • The temperature is attached via a suction cup, and the testing probe has its own suction cup to attach high or low inside your tank
  • Size is small and does not take up a lot of space
  • Easy to install
  • It has a clear LCD display screen


  • Drains through batteries quickly if you do not turn off when not in use
  • Some customers complain that the suction cups do not work very well

Marina Floating Thermometer with Heater

A Marina floating thermometer stays in the water. Thus, it is the best thermometer that can accurately measure the water temperature.

You can leave this type of submergible thermometer floating freely on the water, or you can use the suction cup provided to install it easily on the side of your aquarium in a vertical position. That goes with the accompanying heater as well.

It has a simple design that is easy to use. Make sure to put it at the front of your aquarium so you can check the temperature whenever you want.

It is made of a durable polymer that is tougher than glass, so you cannot easily break it.

The temperature can easily be read and is fairly an accurate reading. It has a safety zone temperature range indicator for most tropical fish. It also has a red indicator light that illuminates when the heater is working.

The Marina Floating Thermometer is perfect for your aquarium. It is inexpensive, and you can be sure that the water temperature in it is perfect for your fish. Great for beginning aquarists.


  • It does not require batteries
  • It has a safety zone temperature range indicator
  • Suction cups are strong
  • Easy to install


  • Although it is not made of glass, it can break if you are not careful
  • If the thermometer is floating in the water, it is hard to read without pulling it out of the tank

SUKRAGRAHA Traditional Stick-on Aquarium Thermometer

This traditional stick-on thermometer is ideal for beginners. It is a vertical strip that is easy to stick outside of your aquarium without falling off—no need for batteries.

Various colors are used to show temperatures in both Celsius and Fahrenheit. It constantly shows the tank’s current temperature and is easy to read.

A bright light shows you the current temperature. When two bright lights show up, the temperature is between the 2 numbers. 

This stick-on thermometer allows you to monitor it easier to know that your temperature is consistent.

This great little thermometer strip does exactly as promised.


  • Sticks well to the side of the fish tank
  • LCD colors are very bright
  • Easy to install
  • No batteries needed


  • It can be hard to read if the lighting is not good
  • It reads the water temperature through the glass, and there are no sensors placed in the water 

JW Pet Company Smarttemp Thermometer

The JW Pet Company Smartemp thermometer is a standing type thermometer that is submersible in water. The great thing about this thermometer is that instead of using a suction cup to make it stay in place, it uses a magnet.

The magnet makes it easy to move the thermometer around the aquarium, especially when cleaning the aquarium.

It is made of glass, but JW has a unique technology of using plastic for its large number display, making it easy to read even from a distance. The thermometer readings are highly accurate, with a green zone for the optimal temperature range.

It is very affordable. It goes to show that good thermometers don’t have to cost much.

So, if you want a submersible thermometer that does not drift away from its place, then give the JW Smart temp thermometer a try.


  • It attaches inside the tank with a magnet, so there are no wires
  • The thermometer is weighted, so it won’t float around the tank if anchored in the substrate
  • Easy to install and read
  • It does not require batteries


  • Made of glass and can break easily
  • It does not work well on large fish tanks above 55 gallons

What is an Aquarium Thermometer?

Most of us know what a thermometer is. An aquarium thermometer is a device that allows you to measure the temperature of the water inside an aquarium.

If you look at the water in an aquarium, you can never tell whether it’s warm or cold. That’s why you need a thermometer. It allows you to confirm that the water inside your tank is the right temperature for your fish.

Benefits of an Aquarium Thermometer

An aquarium thermometer’s most important benefit is that it allows you to measure the water temperature inside your fish tank accurately.

Why is this important? There are several reasons.

  • It helps you check that the temperature throughout the aquarium environment is consistent. With an aquarium thermometer, you can easily monitor the water temperature at different times of the day and in different parts of the aquarium.
  • It can help prevent scenarios where your fish gets stressed because of temperature fluctuations. An aquarium thermometer helps ensure that you have a stable aquarium temperature. It ensures a healthy aquarium that will not harm your fish.
  • It is important when you do partial or complete water changes. You need special monitoring when you change your aquarium water because the temperature changes. Thus, before adding back the fish, you can bring the temperature back to the right one.
  • The right temperature is important to help good bacteria thrive.
  • There are temperature ranges that help bacterial parasites grow in your aquarium. With the thermometer’s help, you can test the fish tank temperature to help combat these pathogens. You can do this by safely increasing the aquarium temperature.

Types of Aquarium Thermometers


A digital aquarium thermometer is a small, rectangular device with a small LCD screen that gives you a very accurate digital reading that is easier to read than other styles.

It comes with a submersible probe connected to the digital display outside the tank. You can connect this probe with wires or wirelessly. You can move it to any area of the tank. This enables you to check water temperature throughout the aquarium.

The split design is so that the electrical component of the thermometer doesn’t get wet.

The thermometer uses batteries with some expensive models that can be mains powered.

Digital aquarium thermometers come with audible alert features that activate when the water temperature goes beyond the set range.

It is very convenient to use but comes with a high price tag. It is very accurate and durable.

Floating or Standing

Floating/standing submersible aquarium thermometers can be left to float on the water or attached to the aquarium’s side using a suction cup or hang inside the tank with a clip. There are also standing thermometers that are weighted so that they sink to the bottom of the aquarium and stand on the substrate.

Since they come in contact with the water, you are assured that the temperature reading is very accurate compared to any other kind.

What is great about these types of thermometers is that they come with a brightly colored “safe zone,” so even if the temperature scale is small in print, you can make a quick visual temperature check whenever you want to.

Floating or standing thermometers can be placed in your tank wherever you want. If your aquarium is large, you can use several of these thermometers so that it is easy to get an overall picture of the temperature. Hence, you can easily identify if there are any cold or hotspots.

The downside to having this thermometer is that it is made of glass. This means that they can tend to break inside your aquarium. This is not a wise choice if your tank has large, boisterous fish.


As the term implies, these kinds of thermometers are those that you stick to the side of the aquarium wall. This type of thermometer usually comes with your aquarium starter pack.

It has a digital temperature display that is fairly easy to read, but these are not true digital thermometers.

This cheap option can measure temperature quite accurately, and it has both Celsius and Fahrenheit scales.

One issue with this type of thermometer is that since it is exposed to the air temperature in the room, it does not measure water temperature accurately.

Also, temperature reading can be affected by the glass’s thickness between the thermometer and the tank water.

You should not place this thermometer in direct sunlight or near heating sources. It is also advised not to put the thermometer below the substrate’s level because of minimal water flow in these areas.

Although not the most accurate thermometer, you can still get a high-quality one and have a consistent room temperature throughout the year.

Features to Consider When Buying an Aquarium Thermometer

Ease of use

Ensure that the thermometer you buy is easy to install and easy to use. It should not have any complex settings. Complicated devices can easily go wrong.

Accuracy and Range

Accuracy is important for an aquarium thermometer. Otherwise, any fluctuation in temperature that cannot be measured by your thermometer can cause significant stress to your fish and plants.

It’s as good as useless if your thermometer cannot give you an accurate reading. This means that you cannot rely on it to give you what you need.

Make sure to check the thermometer accuracy with a properly calibrated digital device.

It is also important to check the temperature range of the thermometer. If the temperature range is too small, it might not measure temperatures suitable for certain types of fish.

Get a thermometer ranging from 50 degrees Fahrenheit to 104 degrees Fahrenheit (10 to 40 degrees Celsius). If you have Coldwater fish, you should get a thermometer with temperature ranges below 20 degrees Celsius.


Durable and high-quality aquarium thermometers may cost you more, but it will surely last longer. Make sure it is made of good quality material because this affects its lifespan and sturdiness.

If you purchase a low-quality thermometer, expect to buy a new one constantly. If this device is to survive in the water, make sure that it is fairly unbreakable. A broken thermometer can easily hurt your fish.

Durable thermometers may be expensive, but it will be all worth it.


LCD stick-on thermometers are easy to read, so are thermometers with large digital displays.

Readability is important when choosing an aquarium thermometer because you constantly need to keep a fish temperature chart. If the thermometer is not readable, it can easily break your fish keeping experience. It is stressful for your eyes, but you can misread the temperature. There is a lot at stake when this happens.

Frequently Asked Questions about Aquarium Thermometers

How do I know if my aquarium thermometer is accurate?

If you have a small or medium-sized aquarium, it is best to place one thermometer at the far end of the tank farthest from the heater. If your tank is large, use several thermometers situated at different points around the tank.u003cbru003eu003cbru003eWhat is important is that the place where you put your thermometer should not make it difficult for you to read. You can put it toward the front of the tank or on one of the sidewalls. Ensure that access to it is unobstructed.u003cbru003eu003cbru003eStick-on thermometers can be placed on the front and the backside of the fish tank. Front placement makes it easier to read.u003cbru003eu003cbru003eYou can install floating glass thermometers on the fish tank’s front or back using suction cups or clips. Digital thermometers must have their probes dipped into the water while the LCD display is kept above.u003cbru003eu003cbru003eMake sure not to put your sticker type thermometer in a dark place. HVAC vents or electrical components can affect its reading, so make sure it is far from these.u003cbru003eu003cbru003eIf you have a glass thermometer, make sure to put it in a place where no objects could break it falling on it.

How do I know if my aquarium thermometer is accurate?

To test a thermometer’s accuracy, you will need a glass filled with ice. Put your thermometer in around 15 seconds. The reading should be 32 degrees Fahrenheit (or O degrees Celsius).u003cbru003eu003cbru003eOr, you can check its accuracy with a properly calibrated digital device.

What should the water temperature in my tank be?

The temperature in your tank will depend on whether you have tropical or Coldwater species.u003cbru003eu003cbru003eIf you have tropical fish, your temperature should be above 68 degrees Fahrenheit year-round.u003cbru003eu003cbru003eIf you have temperate or Coldwater fish, they will need temperatures that are typically between 50 and 60 degrees Fahrenheit year-round.u003cbru003eu003cbru003eAn accurate thermometer will give your fish and aquarium plants the perfect temperature they need to survive.

Can fish die if the water is too cold?

If the water temperature in your aquarium is too cold, then expect your fish to be sluggish and with no appetite to eat. A sudden drop in your aquarium temperature could mean a broken heater.

Final Thoughts about the Best Aquarium Thermometer

Aquarium thermometers are very vital to the life of your fish. Drastic temperature changes can kill your fish. If you are unaware of this, it might be too late for them.

Fish keepers often overlook aquarium thermometers. It is essential for you to achieve a healthy aquarium environment by ensuring that the water temperature in it is optimal.

With a good aquarium thermometer, the environment you create for your fish and aquarium plant will be very favorable. It can save them from fatal disasters.

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