HomeGearX is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn more

10 Best Aquarium Thermometers: Digital, Standing & Stick On

Best Aquarium Thermometer

If you are an aquarist and you live in a cold area, chances are that you have a heating mechanism to warm up your aquarium water so as to create a conducive environment for your fish.

With this mechanism, it is important to keep track of temperature changes in the water in order to stabilize it if it fluctuates a lot or to make any appropriate changes. This is because such fluctuations cause a lot of stress to the fish.

Even if your heater has a built-in thermometer, it is still important to get an external aquarium thermometer so as to double check the readings just in case the one in the heater fails.

This article gives you an in-depth review of the best aquarium thermometers so as to make it easier for you to get a good one for your tank.

Product Name




Current Price

1. Zacro LCD Digital Aquarium Thermometer

Zacro LCD Digital Aquarium Thermometer

Very accurate digital aquarium thermometer with a large and easy to read LCD screen and a slider button to switch between Celsius and Fahrenheit readings


2. American Thermal Aquarium Horizontal Thermometer

American Thermal Aquarium Horizontal Thermometer

Movable stick-on aquarium thermometer with horizontally oriented readings on a scale of 19 - 29°C


3. Sukragraha Traditional Stick on Aquarium Thermometer

Sukragraha Traditional Stick on Aquarium Thermometer

Stick-on aquarium thermometer that displays different readings using different colors and comes as a set of 10 strips


4. Marina Floating Aquarium Thermometer with Suction Cup

Marina Floating Aquarium Thermometer with Suction Cup

Affordable floating aquarium thermometer that is small in size and has a safety zone indicator for indicating the favorable range for tropical fish


5. Keynice Digital Thermometer

Keynice Digital Thermometer

Digital aquarium thermometer with a rechargeable battery and a wide -50°C to 110°C temperature range


6. Risepro Digital Aquarium Thermometer

Risepro Digital Aquarium Thermometer

Easy to install digital thermometer that comes with 2 suctions cup and 2 batteries, one for use, the other a spare


7. LCR Hallcrest A-1005 Aquarium Thermometer

LCR Hallcrest A-1005 Aquarium Thermometer

Easy to read stick-on aquarium thermometer with a narrow range and a color-based temperature display


8. HDE Digital Aquarium Thermometer

HDE Digital Aquarium Thermometer

Highly accurate digital thermometer that comes in a set of 3 and can be used in both fresh and saltwater


9. General Tools AQ150 Aquarium Thermometer

General Tools AQ150 Aquarium Thermometer

Highly advanced digital aquarium thermometer with a high/low-temperature alarm and an accuracy of +/-0.5°C


10. JW Pet Company Smarttemp Aquarium Thermometer

JW Pet Company Smarttemp Aquarium Thermometer

Easy to install in tank thermometer with a magnetic holder and a safe zone that indicates the right temperature range for tropical fish


1. Zacro FBA_ZDT1-AUX-1Our Pick for the Best Aquarium Thermometer

Zacro LCD Digital Aquarium Thermometer
  • Temperature Range: -50°C to 70°C
  • Dimensions: 2.2 × 1.5 inches
  • Weight: 0.32 ounce
  • Battery: LR44 button cell

If you have extremely sensitive aquarium livestock, which prefer to stick to a very narrow temperature range, Zacro’s digital unit is the best one to buy. This is because it gives temperature readings to within 0.1°, making it the most accurate aquarium thermometer.

To sense the temperature, a submersible probe is connected to the thermometer via a 24.88-inch-long cable, and this makes it possible to submerge it into the fish tank while the main unit remains outside the water. This is very important because the thermometer is not waterproof.

Once the measurements are sensed, the results are displayed live on a large and easy to read LCD screen in either Fahrenheit or Celsius units. A slider switch is used to change between these two, enabling you to get temperature readings in your most preferable way.

The benefit of using having a digital thermometer with such a display is that the temperature values are very easy to read as compared to scale readings on other types of thermometers.

However, the unit does require a power source and this is supplied using one LR44 button cell, which is included in the package.


  • Very accurate readings to within 0.1°.
  • Long 24.88-inch cable makes it possible to submerge the probe while the thermometer is above water
  • Large and easy to read LCD screen
  • Gives readings in degrees Celsius and Fahrenheit
  • Comes with its battery


  • Not waterproof
  • Cannot function with a low battery or without a battery

2. American Thermal BC002008Best Stick-on Aquarium Thermometers

American Thermal Aquarium Horizontal Thermometer
  • Temperature Range: 19°C to 29°C
  • Dimensions: 7.4 × 1 inches
  • Weight: 0.32 ounce
  • Battery: N/A

American Thermal’s stick-on unit is a top-rated aquarium thermometer that is very lightweight and requires to be mounted on the outside of an aquarium.

The thermometer’s movable characteristic gives it a very big advantage because it can be unglued from the external aquarium wall, stuck on to a different place and still work.

For installation, this piece must be placed in a horizontal orientation because its measurement readings are printed on the material in such a way that they can be comfortably read in this position.

On the downside, the readings that the thermometer can handle are in a much smaller range of 19°C to 29°C and this limits the extent to which you can use it. Additionally, the unit is not as accurate as a digital one.

However, unlike digital thermometers, batteries are not required for this it to operate. This means you don’t have to worry about not getting your reading once the batteries run out of charge.


  • Movable stick on thermometer
  • Horizontal placement makes it easier to read and use
  • Does not require a battery to run.
  • Lightweight


  • Smaller temperature range
  • Not as accurate as a digital thermometer

3. Sukragraha Traditional Stick on Aquarium ThermometerStick-on Thermometer with Colored Readings

Sukragraha Traditional Stick on Aquarium Thermometer
  • Temperature Range: 18°C to 34°C
  • Dimensions: 5.12 × 0.71 inches
  • Weight: 0.32 ounce
  • Battery: N/A

Sukragraha’s stick on aquarium thermometer has a more traditional design, which requires to be placed vertically along the aquarium wall.

Although the strip’s readings are in a smaller range (14-31°C), they are indicated in both °C and °F, enabling you to use the scale that you prefer most. Additionally, they are very easy to read because the values are only given in discrete numbers.

The unit displays different temperatures using different colors, using blue for the actual water temperature and brown for the higher temperatures. This makes its use very intuitive and much easier to read.

On installation, the product is self-adhesive, with a sticky back that easily sets on the tank wall. If you install it incorrectly, no need to worry. The strip is movable, which means you can remove it from the surface and stick it back correctly or onto a different surface.

Additionally, the set contains 10 pieces and therefore, if one piece gets torn apart as you try to move it, you have 9 more at your disposal.

The only disadvantage with this product is that it might be a bit difficult to read the temperature value in low light.


  • Gives temperature readings in both °C and °F
  • Displays different temperatures using different colors
  • Self-adhesive
  • Movable
  • Comes as a set of 10 thermometers


  • Difficult to read in low light
  • Smaller temperature range

4. Marina 11201A1Best Aquarium Thermometer for the Money

Marina Floating Aquarium Thermometer with Suction Cup
  • Temperature Range: 0°C to 50°C
  • Dimensions: 4.25 × 1 inch
  • Weight: 0.8 ounce
  • Battery: N/A

Marina’s floating aquarium thermometer is the most affordable product in this review but this does not mean that it is substandard.

For starters, the unit is very easy to read. It has a scale that gives the temperature readings in both °C and °F in the range of 0 – 50 and 32 – 122 respectively on its clearly labeled glass wall.

Additionally, it has a safety zone indicator that marks the favorable temperature range for most tropical fish so that you can know whether your tank’s water is conducive at a glance. This makes it one of the best floating aquarium thermometers.

However, it is very small in size (4.25 inches tall) and this means that its readings are very compressed and thus, reading between the lines might be a bit difficult.

The good thing though is that it gives accurate readings because it is placed inside the water and thus, gets the actual temperature from the inside.

For installation, this unit comes with a suction cup, which holds it firmly in position. The only disadvantage is that this suction cup might leave marks on your tank wall after some time.


  • Affordable
  • Gives temperature readings in both °C and °F
  • Safety zone indicator
  • Gives accurate readings because it is placed inside the water
  • Comes with a suction cup for installation


  • Compressed temperature scale makes it difficult to determine the actual temperature
  • The included suction cup leaves ring marks on the tank wall

5. Keynice AP-185-USBDigital Thermometer with a Rechargeable Battery

Keynice Digital Thermometer
  • Temperature Range: -50°C to 110°C
  • Dimensions: 1.89 × 1 inch
  • Weight: 1.6 ounces
  • Battery: Rechargeable battery

Keynice’s product is one of the best digital aquarium thermometers simply because it features a rechargeable battery and has a very wide temperature range of -50 to 110°C.

Due to this large range, this product has a very wide application area, which includes measuring the temperature in flower houses, HVAC air ducts, server rooms, engine rooms and of course, aquariums.

An NTC probe is featured for sensing the temperature levels in the water, and it is connected to the thermometer via a 1-meter long cable. This means that it can be submerged deep into the water for more accurate readings, which in this unit is +/- 1°C.

The readings are shown on its large LCD backlit color display and can be given in either °C or °F. A short-circuiting pull switch at its back is used to change between these two, which might be a bother to some, pulling and pushing it back is quite a simple process.

For charging, USB is used, which means you can hook it up to your computer, power bank or USB charger while it is still being used.


  • Rechargeable battery
  • Wide temperature range of -50 to 110°C
  • Remote NTC probe on a 1-meter long cable for temperature sensing
  • Large LCD backlit color display
  • Convenient USB charging system


  • Short-circuiting pull switch might be a bother to use when switching from °C to °F
  • Not as accurate as other digital thermometers such as Zacro’s unit above

6. Risepro TM-4Easy to Install Digital Aquarium Thermometer

Risepro Digital Aquarium Thermometer
  • Temperature Range: -50°C to 70°C
  • Dimensions: 2.3 × 1.5 inches
  • Weight: 0.3 ounce
  • Battery: LR44 button cell

Risepro’s aquarium thermometer is also very affordable and yet it has some very impressive features. For starters, it has a relatively wide temperature range, which is -50 to 70°C or -58 to 158° on the Fahrenheit scale.

A sliding button is used to switch between these two units while the values are displayed on a large LCD screen.

The thermometer can be easily installed because it comes with two suction cups for mounting onto the outside tank wall while a probe on the end of a meter-long cable dips into the water to get the temperature readings.

An important thing to note is that the digital thermometer itself is not waterproof and thus, it should only be mounted outside the aquarium.

For power, this piece uses an LR44 button cell, which it comes with plus a spare one for when the current one runs out of charge.

On the downside, the thermometer’s accuracy is a bit off at +/-1°C, but this is much better than in non-digital units.


  • Affordable
  • Displays temperature reading both in °C and °F
  • Comes with two suction cups for a quick set up
  • Meter long cable suspends the probe deep into the water
  • Comes with its button cell plus a spare one


  • Not waterproof
  • Accuracy is not that high as compared to other digital units

7. LCR Hallcrest A-1005Easy to Read stick-on Aquarium Thermometer

LCR Hallcrest A-1005 Aquarium Thermometer
  • Temperature Range: 19°C to 29°C
  • Dimensions: 7.3 × 0.75 inches
  • Weight: 0.6 ounce
  • Battery: N/A

The A-1005 is a liquid crystal vertical aquarium thermometer that mounts vertically outside your fish tank.

It is quite easy to set up because of its sticky back, which adheres tightly to the aquarium wall and is also easily removable in instances where you may want to clean the tank or use the unit on a different aquarium.

On the scale, this stick-on thermometer only features measurements given in °F on a range of 66 – 84, which is roughly 19 – 29°C.

This is quite a small range but with the liquid crystal temperature indicator, it is quite accurate and easy to read. However, in low lighting, an external lighting source is required in order to make the reading more visible.

A color code is used to display the temperatures, with the green box showing the actual temperature, brown box showing the higher reading and blue box showing the temperature below. With these, you can figure out and also monitor the temperature changes easily.


  • Easy to install by sticking onto the wall surface
  • Movable
  • Liquid crystals with a color-coded display


  • A bit difficult to read in the dark
  • Measurements on the scale are only given in °F

8. HDE Digital Aquarium ThermometerBest Value Pack for Owners with Multiple Tanks

HDE Digital Aquarium Thermometer
  • Temperature Range: -50°C to 70°C
  • Dimensions: 2 × 1.25 inches
  • Weight: 3.84 ounces
  • Battery: LR44 button cell

HDE’s digital aquarium thermometer is certainly not very affordable as compared to the other units but it comes as a set of 3 digital thermometers, which make the cost per unit very low and thus, makes it the best value pack for owners with multiple tanks.

Additionally, the units are great for fresh or saltwater aquariums and thus, can be used on all kinds of tanks from amphibian or reptile terrariums to regular fish tanks and many others. Therefore, if you have multiple tanks, these 3 pieces are compatible with all of them.

In terms of design, this thermometer has a large and easy to read LCD screen that can display the temperature readings in either Fahrenheit or Celsius, depending on the setting that you make using the slider switch below the screen.   

However, it is important to note that this unit is not waterproof and thus, it should not be submerged into the water. Only the probe should go into the water.

Other features include the inclusion of LR44 batteries for powering it and an accuracy of +/-0.1°, making it one of the best digital aquarium thermometers.


  • Comes as a pack of 3 thermometers
  • Compatible with fresh and saltwater tanks
  • Large and easy to read LCD screen.
  • Comes with its batteries
  • Very high accuracy


  • Not waterproof.
  • Cannot function without a battery

9. General Tools AQ150Very Advanced Digital Aquarium Thermometer

General Tools AQ150 Aquarium Thermometer
  • Temperature Range: -50°C to 70°C
  • Dimensions: 2.9 × 2 inches
  • Weight: 1.6 ounces
  • Battery: CR2032 button battery

General Tools’ aquarium thermometer is a very expensive product but it has some very impressive features that make it quite unique.

For starters, it is a digital unit and has a high and low-temperature alarm, which ensures that you keep the water temperature within the set range. This alarm automatically turns on when the water temperature goes below or above the limits of this range.

The thermometer can also be used to measure the room or water temperature by toggling with the ambient and remote sensor temperature buttons, making its use very versatile.

Setting to ambient measures the room temperature while the remote sensor setting requires a remotely connected probe so as to get the readings from it.  

Other features include a large LCD display, a range of -50 to 70°C, toggling between Fahrenheit and Celsius display and an accuracy of +/-0.5°C.


  • High and low-temperature alarm
  • Ambient and remote temperature sensing
  • Large LCD display
  • Can display the temperature in either Fahrenheit or Celsius
  • A wide range of -50 to 70°C


  • Not as accurate as other digital thermometers
  • Expensive

10. JW Pet 21600Easy to Install in Tank Thermometer

JW Pet Company Smarttemp Aquarium Thermometer
  • Temperature Range: -1°C to 40°C
  • Dimensions: 5.6 × 0.5 inches
  • Weight: 1.12 ounces
  • Battery: N/A

JW Pet’s Smarttemp unit is an in-tank aquarium thermometer that is secured in place using a magnet and thus, no suction cups are required.

This makes it superbly easy to install because all you have to do is make sure that the magnet on the outside is holding the thermometer firmly on the inside.

In terms of size, the Smarttemp measures 5.6 inches in height and on this column, it can measure a range of -1 to 40°C or 30 to 104°F.

A safe zone is clearly marked in green on the scale’s midpoint and it shows the safe temperatures that are conducive for keeping tropical fish, making the work easier for you.

For accuracy, this unit is correct to within +/-1.5°F, which is a good option relative to other in-tank thermometers, but still not as good as in digital thermometers. 


  • Magnetic installation
  • Relatively wide range for an in-tank thermometer.
  • Safe zone marking


  • Not very accurate

How to Buy the Best Aquarium Thermometers

How to Buy the Best Aquarium Thermometer

1. Type of Aquarium Thermometer


Digital aquarium thermometers are the most advanced of the 3 types of aquarium thermometers and consequently, are more expensive.

However, they have features such as LCD screens for easy reading, remote sensor probes, high accuracy and have alert features that sound an alarm when the water temperature is too low or too high past the set range.


  • Remote temperature sensing using a probe
  • Easy to read
  • Highly accurate
  • Features alert functionalities


  • Expensive
  • Requires batteries to run

Standing or floating

This type is usually placed in the water and this gives it the benefit of getting the direct temperature reading from the inside.

A variety of them exist, for instance, those that are stuck inside the tank using suction cups, others are suspended using magnets while the rest simply float on the water.

Instead of alarm systems, these units usually have safe zones indicated on them using a green color, and these can be used to check if the temperature is suitable for tropical fish or not.

On the downside, most of them are made of glass, which is very brittle, and they are not as accurate as digital units.


  • Features safe zones
  • Can be placed almost anywhere inside the tank
  • They are not affected by room temperature since they are submerged
  • Less expensive than digital thermometers


  • Brittle glass construction
  • No alert features
  • Less accurate than digital thermometers

Stick on

This is the most widely used type because it is affordable and most tanks come with it as an accessory.

Although some refer to these as LCD thermometers, this is not entirely true. Some of them have colors that indicate the current water temperature and this is what makes people think that they have LCD. However, these colors are usually very dull and thus, hard to read in low light.

The other disadvantage with these is that they can be affected by room temperature. Therefore, for the best results, avoid placing them under direct sunlight or below the gravel so as not to affect its accuracy.

On the bright side, most stick-on units are easy to install, movable and feature Fahrenheit and Celsius scales for more customized readings.


  • Affordable
  • Easy to install
  • Movable


  • Hard to read in low light
  • Not as accurate as digital thermometers

#2. Temperature Range and Accuracy

A thermometer’s temperature range is important to consider because it gives the limits to which the unit can be used.

For aquariums, since freezing and boiling is not required, a range of about 10°C to 40°C is enough for the job. The goal here is to monitor the water and ensure that it remains at the conducive level, which falls within this bracket.

In addition to that, the thermometer should be accurate to within at least +/-1°C so that it does not throw you off while thinking that you have the correct reading. The more accurate, the better.

3. Readability

Of course, a thermometer is only as good as its readability. If you cannot be able to read the scale, it will be useless to you.

Digital thermometers are the easiest to read because they display the value clearly on a big screen. Color changing stick-on units are also easy to read since they highlight the actual temperature value in a different color.

However, mercury-based ones can be challenging because getting the exact point that the red line has settled on can be a big task, especially if your eyes are weak.

4. Ease of installation and usage

Floating and stick-on thermometers are usually very easy to install using either suction cups, magnets or sticky surfaces for the stick-on type. They are also easy to use because they are waterproof and thus, no special care is required.

However, digital thermometers require to be installed carefully because they can be damaged by water and they require some few extra steps when using them but this is usually not very complex.

How to Read an Aquarium Thermometer Sticker/ Strip

While installing a thermometer strip is easy, reading it might be a challenge. However, the following colors will help you figure out how it’s done.

Blue: Blue usually indicates the temperature below the tank’s actual temperature

Red: Red indicates the exact value above the actual value.

The real value: The real water temperature will be in the middle of these two and in a green color. This is what you should read as the actual water temperature.


As you can see, there are different kinds of aquarium thermometers. Choosing one for your tank, especially as a beginner, might be a hard task but after reading through this article, it should be much easier to pick the best aquarium thermometer that suits you and your tank’s needs.