Best Aquarium Thermometer


Aquariums add to the ambience of your home. It brings the nature closer to you with minute details. You need to take care of the fish , their comfort, food and water temperature. Usually, with the changing weather the water temperature changes.

Most of the time, the aquarium owners add nano water heaters during winters and leave it unattended so the water temperature may rise more than necessary. However, do not make abrupt changes in the water temperature. It is better to have an aquarium digital thermometer so that you check the water temperature more accurately and add warm or cold water. For this reason, we have enlisted some of the best thermometers for aquarium.



Top Pick

JW Smarttemp Thermometer

  • Temperature: 40 Degrees Celsius
  • Item Length: 4 inches

Best Food Safe Material

Cooper Atkins DFP450W

  • Temperature: 450 Degrees Fahrenheit
  • Item Length: 19 millimeters

Best Digital Thermometer

Zacro LCD Digital Aquarium Thermometer

  • Temperature: 50 degree Celsius
  • Item Length: 3.6 inches

Best Glass Material

Marina Floating Thermometer with Suction Cup

  • Item Length: 7  inches
  • Color: Basic pack

Best Powered Battery

VIVOSUN LCD Digital Aquarium Thermometer

  • Response Time: 500 Milliseconds
  • Power Source: Battery Powered

Wide Temperature Range

AQUANEAT 3 Pack Aquarium Thermometer

  • POWER SOURCE: Battery Powered
  • Material: Plastic

Color Coded

LCR Hallcrest A-1005 Vertical Thermometer

  • Response Time: 500 Milliseconds
  • Item Length: 6.75 inches

Best Aquarium Thermometer

At times, it can be overwhelming to decide from a variety of products available. However, you cannot pick and choose any of it without considering the features and properties. Therefore, here we have enlisted few of the best aquarium thermometers. You can read through them, and make your final purchase.

1. JW Smarttemp Thermometer

best aquarium thermometer

JW smarttemp thermometer is a kind of stick-on thermometer that has all what it takes to be the best device for aquarium. Most importantly, it is free from mercury, instead the manufacturers use alcohol in its place. So, there would be no harm to your fish if it seeps in the tank.

It has the easiest installation process with magnetic fastening system. You get a magnet for the outer side of the aquarium to secure the accurate thermometer at its place. Just place main part of the fish tank thermometer inside the tank and secure it with the magnet from the outside. So you need not fear of loosing your thermometer if the sticking glue does not stay for long in water 

The large numbers on scale and the white background help you in reading the temperature clearly. Moreover, it has an indication for the safe area with green color. With this indication you get the range where it is the standard and optimum temperature.

digital aquarium thermometer

Key Features

  • It is made of glass.
  • It is a mixture of floating and stick-on aquarium thermometer.
  • It has magnetic fastening system.
  • It is free from mercury.


  • It has large scale number which makes it extremely easy to read.
  • It has strong suction power so, it stays on the aquarium wall.
  • You can get the highly accurate temperature.


  • The front magnet may fall off and make the product sink.
  • The glass body may rupture due to water pressure or fish collision.

Tester’s verdict

Overall. The testing team is all praise for this product and its features. However, the setback that we feel is the fragility of the device and the outer magnet. It can make the product sink if it moves from its place accidently.

JW Smarttemp Thermometer

The price of “JW Smarttemp Thermometer” varies, so check the latest price at

2. Cooper Atkins DFP450W

best thermometer for aquarium

This product is deal for the people who do not want to permanently fix a digital thermometer in their aquarium. You can use is as a portable aquarium digital thermometer to check the tank temperature. Moreover, it can also be used while cooking food to check the heating of oil and other stuff as it is made of food grade material.

It is super easy to use this temperature device. Remove the covering sleeve, insert it in aquarium, and get the reading. This device also comes with an alarm feature which blinks the digital display unit once you reach the optimal temperature.

You do not have to wait too long for the device’s response. The manufacturers claim that this product take sonly 6 second to record and show the reading on LCD digital aquarium thermometer. Moreover, you will have to convert the Fahrenheit to Celsius yourself as it does not measure in Celsius.

best thermometer for fish tank

Key Features

  • It is a testing gauge.
  • It gives the reading in 6 seconds.
  • It is a kind of digital aquarium thermometer.
  • It has a visual alarm.
  • It has food safe material.


  • It is easy to use.
  • It gives highly accurate LCD readings.
  • It is a multipurpose product, you can use it other than aquarium as well.


  • It cannot be fixed inside the aquarium.
  • It does not measure in Celsius.

Tester’s verdict

The testers of this product find it to be the best digital aquarium thermometer to use for multiple purposes. It is easy to use and gives accurate LCD readout but cannot be fixed permanently in the aquarium. Thus, it is not solely for your fish tank. Also, it does not measure in Celsius.

Cooper Atkins DFP450W

The price of “Cooper Atkins DFP450W” varies, so check the latest price at

3. Zacro LCD Digital Aquarium Thermometer

aquarium thermometer

Zacro LCD digital aquarium thermometer, the name is self-explanatory. This product is a digital device that gives you the most accurate reading. It comes with a probe and suction cups. You have to insert the temperature probe in water and use the suction cup to secure the aquarium thermometer.

The large digital display makes it easier to read the numbers. Also, the compact design of the device takes up lesser space in your aquarium. In this way the fish can roam around without obstacles. You need not fear of any damage to the device.

You can use this LCD digital aquarium thermometer for fresh water, salt water and tap water as well. Also, it runs on batteries so you need not worry about excessive electricity bill.

most accurate aquarium thermometer

Key Features

  • It is a digital aquarium thermometer.
  • It has small volume that takes up less space in your aquarium.
  • The range is between 50-70 degrees Celsius.
  • It runs on batteries.


  • It is high durability.
  • It has easy installation process.
  • It has easy operation and functioning.
  • It has strong suction power.


  • The fish tank thermometer accuracy may reduce with the passing time.

Testers verdict

Overall, this product is fine and perfect to use in an aquarium. It is compact, durable and has easy operation. However, with the passing time, the testers found a significant difference in the readings’ accuracy.

Zacro LCD Digital Aquarium Thermometer

The price of “Zacro LCD Digital Aquarium Thermometer” varies, so check the latest price at

4. Marina Floating Thermometer with Suction Cup

fish tank thermometer

Marina floating thermometer is of a traditional design. It is made of glass material and has dyed alcohol in it for the indication of temperature. The red liquid rises to show the temperature on scale. Also, it has a green zone to reflect the safe temperature.

It comes with the suction cup that you can use to fix it. You can either adhere it on the side walls or make it stand on the bottom level. However, it is better to fix on the walls to make it easier to read the temperature.

You can use these aquarium thermometers in fresh water and salt water. Marina floating thermometer with suction works the best for the tropical fish. Thus, the simple and effective design of the device makes it easier to use.

best water thermometer

Key Features

  • It is a floating thermometer.
  • It has the glass material.
  • It has safe zone indication.
  • It is free from mercury.


  • It gives accurate LCD readout.
  • It is easy to read the scale.
  • It has strong suction power.


  • The suction cups leave marks on the fish tanks.
  • The glass material is fragile.

Tester’s verdict

As a whole this thermometer is good to use for accurate temperature readings. However, the installation mechanism may harm your fish tank as the suction cup damages the tank walls.

Marina Floating Thermometer with Suction Cup

The price of “Marina Floating Thermometer with Suction Cup” varies, so check the latest price at

5. VIVOSUN LCD Digital Aquarium Thermometer

digital thermometer aquarium

These digital aquarium thermometers are best suitable to get the exact reading. It has the range of 50-70 degrees Celsius. However, it works in both the parameters i.e., Fahrenheit and Celsius.

You can put the probe inside the aquarium at any place, it will not affect the temperature range. Moreover, the large digital display makes it easier for you to read the figures regardless of the distance.

It has the feature of shifting between Celsius and Fahrenheit. For this purpose, you have to long press the power button. It comes with two suction cups that you can sue for the device and the probe to make them stay at the place.

most accurate aquarium thermometer

Key Features

  • It is a digital aquarium thermometer.
  • It comes with a long cable.
  • It can shift between Celsius and Fahrenheit.
  • It is powered by battery.


  • It is easy to read.
  • It has a large digital display.
  • It has a waterproof probe.


  • Suction cup may not stay in the place.

Tester’s verdict

The testing group has found this product to be excellent for use. It has long wires and large thermometer LCD display allows easy reading. However, the suction cup does not really do its job as it frequently move from their place.

VIVOSUN LCD Digital Aquarium Thermometer

The price of “VIVOSUN LCD Digital Aquarium Thermometer” varies, so check the latest price at

6. AQUANEAT 3 Pack Aquarium Thermometer

aquarium digital thermometer

This digital device comes with two suction cups. It has easy installation process. Use one suction cup with the device and other with the probe. It will help them stay still at the place. It has a large digital display which make sit easier to read even form a distance.

This product is suitable for different types of waters from fresh water to salt water. It works effectively with a wide range of temperature. Moreover, it does not cost you electricity bill as it runs on battery. Plus, you get extra button cells in the package as well.

Aquaneat gives the most exact reading when it comes to the comparison to other digital aquarium thermometer. Hence if you are a perfectionist, you need to get your hand son this product as soon as possible.


best fish tank thermometer

Key Features

  • It is a digital aquarium thermometer.
  • It comes with two free extra button cells.
  • It has a wide temperature range.
  • It runs on battery


  • It is easy to install.
  • It is easy to read.
  • It gives accurate thermal figures.


  • The suction cups may warn out and move out of place.

Tester’s verdict

The aquaneat thermometer is among the most in in demand products. It has a wide temperature range with high accuracy rate. The only setback the testers feel is the durability of the suction cup.

AQUANEAT 3 Pack Aquarium Thermometer

The price of “AQUANEAT 3 Pack Aquarium Thermometer” varies, so check the latest price at

7. LCR Hallcrest A-1005 Vertical Aquarium Thermometer

digital thermometer for aquarium

This product is ideal for the constant use. It has simple design and mechanism yet it gives the accurate reading. It requires no assembling of the product as it comes as one piece. You have to stick it on the aquarium’s wall for monitoring.

The manufacturers claim that it is a moveable aquarium thermometer which means you shift the places without fearing about the adhesive. You must stick it on the outside of aquarium and keep it away from the sunshine and heater.

It is a color coded product. You have to read the temperature according to the colors. The green color shows the safe zone while the brown color indicates the higher degree and the blue reflects the lower degree.  So you can figure out with the color when the temperature variates.

best water thermometer

Key Features

  • It is a stick-on aquarium thermometer.
  • It requires no assembling.
  • It is a moveable thermometer.
  • It is color coded.


  • It gives accurate readings.
  • It has strong suction power for fastening.


  • You cannot read the accurate thermometer without flash light.

Testers verdict

This testing device is perfect for the user who are into simpler things. Yet it gives the accurate readings. However, you will have to use a flash light to read it clearly.

LCR Hallcrest A-1005 Vertical Aquarium Thermometer

The price of “LCR Hallcrest A-1005 Vertical Aquarium Thermometer” varies, so check the latest price at

Things to Consider When Buying a Best Thermometer for Aquarium

You cannot blindly select a thermometer for your aquarium without checking on its features and properties. There are a few things to consider when buying the best fish tank thermometer, so, that you do not regret later with other thermometers.


There is no point in buying a thermometer if you do not get the accurate temperature reading. The error in tank temperature detection can be fatal for the tank inhabitants. Therefore, when buying aquarium thermometers, test its accuracy or get the digitized products for less error in figures.

For the most accurate results you can go for the LCD digital aquarium thermometer that automatically shows the figure on LCD display screen. With this advancement the factor of human error is eliminated. Thus, you can be sure about the accuracy with a LCD digital aquarium thermometer instead of a manual reading thermometer.


The range of the thermometer matters a lot. You must get an aquarium thermometer that has the range of 65-85 degrees Fahrenheit (18-29 degrees Celsius). These temperature ranges may vary with the size of your aquarium. So, you should get the thermometer according to the size and capacity of the fish tank.

The temperature is a sensitive element when it comes to the aquarium and its inhabitants. The inappropriate temperature will not only harm the fish but will also affect the beneficial bacteria. Eventually, there will be a bacterial imbalance in the aquarium water that makes it cloudy or murky.


You will not want to spend your hard-earned money time and again on buying aquarium thermometers. So, it would be wise of you if you get a good quality thermometer that will last you for long. It would work best if you get the right type of thermometer for the aquarium to save some bucks.

If you get a low-quality thermometer there are fair chances that the mercury thermometer will leak in the aquarium after some time. While the LCD digital aquarium thermometer’s LCD display may stop working after few days. As a result, you will have to buy new ones, so, isn’t it better to get good quality and durable product at the first time

Easy Operation

The most attractive feature of any product is the ease of use. There is no hard job for the thermometers, they tell you the water temperature in your fish tank. For this reason, there has to be no complicated mechanism so that every lay man can use it.

There should be an easy installation process so that the aquarium owners do not require professional assistance in its operation. We are not questioning the worth of other thermometers, instead we want a smooth experience for the customers with best aquarium thermometers.

Type of Thermometer

There are different types of fish tank thermometers for various aquarium setups. You can find three main types of aquarium thermometers in market i.e., floating thermometers, stick-on, and digital thermometer.

Floating Thermometers

Floating thermometers are also known as the standing thermometers that used to have mercury in them. However, with the ban on mercury usage in aquarium thermometers, ethanol or other form of dyed alcohol is added in these thermometers.

You can get nearest to the accurate temperature with the glass thermometers. To use this product, you will have to hang it inside the fish tank or use a floating thermometer with suction to secure it in its place at a standing position. You may need quite a few of these thermometers to use on all sides of aquarium if it is large in size.

However, there are some setbacks of this type of thermometer. The glass body can rupture due to fish collision or current waves, making this type of thermometer more fragile than others. Moreover, the small scales will be difficult to read from outside of the aquarium. Hence, there can be a human error in reading in this way.

Stick-on Thermometers

The name says it all, the stick-on thermometers are the easiest type to use. You have to stick it on the outside of the fish tank. First clean and dry the outer walls of the aquarium. Stick it on and you are all set to go. The temperature range is given at the end of the stick-on thermometer.

It is quite easy to read this type of thermometer because there is clarity and the current temperature is highlighted. So you need not put extra efforts to read it. However, do not place it in direct sunlight or heat as it will highly affect the accuracy rate.

Although, it is an easy-to-use device but there are some factors that can affect the accuracy. For instances, the thickness of aquarium walls may be a hinderance for accurate temperature detection. Also, the external environment of the room can also have a direct impact on the accuracy of temperature.

Digital Thermometers

Digital thermometers are the most popular among all the types and the best aquarium thermometers. It comes with a probe that goes inside the water tank. You have to connect the probe with the LCD digital aquarium thermometer through a cable. The device is designed in a way that it can stay in water for constant monitoring of temperature, or you can take it out when not in use.

The digital thermometers often use batteries to function, however, there are some products that you can connect directly to the electric socket. The digitization of the product makes it the most expensive one among all the types of aquarium thermometers, but a high quality product can prove to a great investment.

The accuracy rate is higher in the digital aquarium thermometer. There is no hassle for reading the temperature as it appears on the LCD display. Moreover, most of the digital temperature devices come with audio sensors. These sensors alert you when the temperature of the water tank increases or decreases from the standard range.


Is There Mercury in Aquarium Thermometer?

No, there is no mercury in aquarium thermometer due the ban on the use of mercury because of its harmful effects on marine life. However, there is dyed alcohol or ethanol in aquarium thermometer which is usually red in color.

How Do I Read the Thermometer?

Usually, there are different temperatures on a thermometer, Fahrenheit and Celsius. If you are using a digital thermometer the figure will appear on the LCD display with the most accuracy. However, if you have a stick-on thermometer than the temperature number on the scale will be highlighted. While with the floating thermometer you will have to notice the color raise an dread the scale.  

Where to Put a Stick-On Thermometer in an Aquarium?

A stick-on thermometer should be placed outside the aquarium. Clean the aquarium walls and dry them completely. Stick on the thermometer on the front wall on the aquarium. Make sure, it is below the water level to get the exact temperature of water. Also, it should not be in contact with direct sunlight or venting areas to prevent the external affect on temperature accuracy.  


A responsible aquarium owner will never neglect the temperature of water tank. It is as necessary to maintain the fish tank’s temperature as for humans. The sudden rise and fall of the temperature can be fatal for the fish inside. The changing weather conditions are responsible for the change in the tank’s water temperature.

There are various types of thermometers that you can use for your aquarium. For instance, you can get a floating, stick-on or a digital aquarium thermometer. You should get the device according to the needs and size of your fish tank and your budget as well.

When making a purchase for aquarium thermometer, consider a few important things. These include, accuracy, range, durability and the procedure of using the device. Try to get a device that has no complicated process of installation or usage; the simpler the better as long as you get the accurate results.

Cody Mitchell
Cody Mitchell is a pet lover and a passionate pet writer. He has worked as a professional writer for over 6 years, with a focus on creating compelling content for pet-related brands. His work has been featured in major publications. When he's not writing, Cody can be found playing with his two dogs (a labradoodle and a cocker spaniel) or cuddling his cat.

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