You need to look after and maintain your aquarium properly for your fish to flourish, and part of this is ensuring the temperature is correct. Both freshwater fish and saltwater fish often have strict range the temperature needs to fall between.

Some fish, and especially plants and corals are a bit fickle when it comes to temperature. If the temperature is too high or too low then it will have an impact on the health of the inhabitants of your tank. You need a thermometer if you require an aquarium heater for your tank.

In this article we will go through the 11 best aquarium thermometers, and also guide you through the different types and styles of thermometer there are available and how best to choose one for your aquarium.

Best Aquarium Thermometers  – Complete 2020 Guide

What Types of Aquarium Thermometer Are There?

There are three main types and styles of aquarium thermometer available on the market. Have a read through each one, and you will see which one will be best suited for your aquarium.

Stick On Aquarium Thermometer

LCR Hallcrest Stick On Aquarium ThermometerStick on aquarium thermometers are the simplest of the three major types you can get. As per the name they simply stick on to the outside of the aquarium glass and read the temperature of the water inside. Make sure you clean the glass well and properly dry it before attaching the thermometer.

As they are not directly in contact with the water this is the least reliable thermometer type. As they are outside the aquarium they can also be influenced by the ambient temperature of the room, making them even less precise. 

They need to be placed away from direct sunlight or light from bulbs, or anything else that will influence the temperature reading such as heaters. You also can’t put the thermometer above the waterline or below the substrate level. You want the temperature of the water, not the gravel or the air above!

It is also best if the stick on aquarium thermometer is placed somewhere where it can be viewed directly face on, as this is where you will get the best reading. If you have to twist and do yoga to view the strip it will soon get very annoying!!

They are also known as LCD thermometers as they show the temperature on an LCD display. But it’s a very simple one, not the one you’ll have on your TV! Some manufacturers have tried to pull the wool over people’s eyes a bit by calling them digital thermometers, but they aren’t really.

It can be a little strange to read these thermometers if you haven’t had one before. There are three temperatures shown in three different colors. The middle temperature is the actual temperature, and is usually shown in green. The temperature below this is usually shown in blue, and is the lower limit. The temperature shown above is usually red, and is the upper temperature limit. 

Note: Usually a stick on thermometer is fine unless you have fish or plants which require a narrow temperature range

Floating Aquarium Thermometer

This type of aquarium thermometer is submerged in the water. As with an old school thermometer you might find in a classroom the temperature is read from the scale on the side of the thermometer. This can be hard to read, so some are color coordinated for easy reading.

You will need to check this type of thermometer periodically to ensure the water temperature is still within the desired range. As it is just essentially a glass, steel, or plastic tube it won’t give you alerts!

Be aware that if you get a glass aquarium thermometer that it can be very fragile, and the last thing you want is for the thermometer to break or shatter in your tank and for glass to be floating around!

Models of this type tend to be very cheap and cheerful. If you have a larger tank you may need more than one of these to give you an indication of the temperature of the whole tank. But the cheap price allows for this easily.

Digital Aquarium Thermometer

This type of aquarium thermometer will probably cost you the most of the three main types. As it is digitalized it is more accurate than the other types and more sophisticated. You can find some digital aquarium thermometers for a reasonable price however, though be careful they don’t skimp on build quality to lower the price.

Digital aquarium thermometers consist of a probe connected to an LED screen. The probe contains the thermometer and records the temperature of the water which is then transmitted and shown on the LED screen. The probe and screen are normally connected with a wire, though there are wireless models available.

The probe is inserted into the water, which then records the temperature. It can either be left in to continuous monitor temperature, or can be used intermittently. The probe is not influenced by the ambient temperature of the room, so is more accurate. Some models may have an alert which signals you if the temperature moves out of the desired range.

If you have a larger tank you may want to have multiple digital aquarium thermometers. If you place them at various points in your tank it will enable you to see if you have a discrepancy or variation in the temperature across the water.

11 Best Aquarium Thermometer Reviews

11 Best Aquarium Thermometer Reviews

There are many different products and models to choose from, and it can get quite confusing. But hopefully after reading that little guide you will have some knowledge so you can choose the best thermometer for your tank.

So here we lay out 11 of the best aquarium thermometers on the market today. 

1. Keynice Digital Aquarium Thermometer

Keynice Digital Aquarium Thermometer
A great digital thermometer with a temperature range of -58F to 230F (-50°C to +110°C) and accurate ±1℃. It measures the temperature every 0.25 seconds. Complete with a 12-month warranty

This aquarium thermometer by Keynice is a great way to start off this list. It has a great price tag for the product you get, and it is accurate to one degree.

The display is back lit for easy readings even in darkened rooms, and the temperature is displayed in either Celsius or Fahrenheit. The display also has a graphical display to show whether you are in a low, medium, or normal range.

The model is powered with a USB connection, which will save you money on batteries in the long run, which is a major downside to other digital thermometer models. However you need to have a place to plug it in.

The temperature reading automatically updates every 2.5 seconds, giving you a very accurate reading. The probe is made of stainless steel so is rust proof, which is useful for having in an aquarium!

The only downside is that the screen is a little bright, and the probe cord could be a little longer.

2. LCR Hallcrest Vertical Aquarium Thermometer

LCR Hallcrest Vertical Aquarium Thermometer
  • Easy To Read
  • Mounts Vertically On The Outside Of Your Aquarium
  • Easily Movable

This is the best aquarium thermometer by LCR Hallcrest. It is a stick on thermometer and is very cheap, yet you still get very accurate temperature readings.

Simply attach this thermometer to the outside of your aquarium and it will begin to record the temperature. As it is on the outside there will be some disparity between the temperature shown and the actual temperature, but keep it away from heat sources and this difference will be minimal.

There will be three colored boxes lit up on the thermometer. The middle green box is the actual temperature, while the blue one below is the lower limit and the brown box above the upper limit.

As it is a stick on thermometer, put it somewhere on your tank which is in easy reach, so you can see the temperature easily!

3. Zacro LCD Digital Aquarium Thermometer

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Zacro LCD Digital Terrarium Aquarium Thermometer
Suitable for all freshwater and marine aquariums. You can choose either Fahrenheit or Celsius according to your need. The temperature data is clearly on the LCD screen. Has a large temperature range with 1 degree deviation

You can use this little aquarium thermometer by Zarco on any freshwater, saltwater, or tropical tank. It is very small at 2.2 x 1.5 inches, and the probe is plenty long enough to get into your tank.

This thermometer is battery powered with the required LR44 battery included, so you don’t need to worry about being near a power outlet, but you will need to make sure you have spare batteries!

The temperature is shown on an LCD screen, and can be changed from Celsius to Fahrenheit depending on your preference. As per most aquarium thermometers there is a one degree variation in the reading.

It is very simple to set up; the thermometer display has a suction cup on the back so you can attach it to your aquarium for ease of use, and the probe goes into the water. Just don’t put the display in the water by mistake!

4. Vivosun LCD Digital Aquarium Thermometer

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Vivosun LCD Digital Aquarium Thermometer
Displays an accurate temperature reading, and can be placed in the aquarium using teo easy suction cups. Runs on a long lasting LR44 battery.

As per most aquarium thermometers, this model by Vivosun displays an accurate temperature reading to within a degree of accuracy. It runs on a long lasting LR44 battery.

The display is a large LCD screen which is nice and easy to read, and you can switch between Celsius and Fahrenheit easily. 

Installation is very simple. The display is attached to the outside of the tank via a suction cup, and there is another suction cup attached to the probe so you can put it in the tank where you like. This is really useful as you won’t have the probe hanging free in the water. The probe cable is one metre long, so is plenty long enough even for very large tanks.

The probe is high quality and is fully waterproof so you don’t need to worry about the cord breaking or rupturing whilst in use.

However there are reportedly some issues with the suction cups adhering to the aquarium side, so give them an extra bit of muscle to ensure they are attached properly.

5. Capetsma Digital Touch Screen Aquarium Thermometer

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Capetsma Digital Touch Screen Aquarium Thermometer
There are no probes or messy wires in water; simply stick this sensor on the outside glass of the fish tank. This prevents water infiltration and electronic oxidation.

This is a very high-tech stick on thermometer by Capetsma. To install it you simply need to attach it to the glass of your aquarium. The sensor is at the back of the unit and will measure the temperature through the glass. It doesn’t need to be in water so you won’t have any extra cords in your tank.

The large see through screen is very cool. The temperature is very prominently displayed so it is easy to see, but the main thing about it is that it is a touch screen. 

You can use this touch screen to set an upper and lower temperature limit, and the unit will flash if the temperature strays from this pre-set range. Don’t underestimate how useful this feature is!

It runs on a CR2032 battery which is hidden underneath the solid panel. The set temperature limits will reset when you change the battery so be sure to look at what temperatures you need before you take out the battery!

6. Windbells Digital LCD Aquarium Thermometer

Neptonion Aquarium Thermometer LCD Digital Aquarium Thermometer with Suction Cup Fish Tank Water Terrarium Temperature for Fish and Reptiles Like Lizard and Turtle
  • 👸 - Easy to read : With compact design ,The Large LCD display unit is easy to read.
  • 👋 - °F / ℃ : It records a wide range of temperature (can be read in Celsius or Fahrenheit), which makes it exceptionally useful in that you can use it in any kind of fish tank.
  • ⏰ - Precise : Displaying temperature measurements within 0.1 degrees! And has a temperature range from -50 to +70 degrees celsius.
  • 💪 - Easy to set up : This thermometer comes with two parts that have suction cups that simplify the mounting process.
  • 💊 - Durable : it’s powered by one LR44 battery. These are very long lasting and easy to replace. Making this a great choice if you’re looking for an accurate and durable thermometer.

This is a great digital aquarium thermometer by Windbells. It comes as a two pack which is extremely useful if you have a large tank and want readings from multiple areas of the tank. There is also the option to get only one if you have a normal tank as well.

The LCD screen is large and easy to read in a compact design. You can switch between Celsius and Fahrenheit as you please, and it has a very large temperature range.

It measures the temperature very accurately to within 0.1 degrees, so if you need a very precise measurement this is the model to go for.

It is very easy to install. The model comes with the required LR44 battery, which is long lasting so you don’t need to replace it often. There is a suction cup on both the probe and the LCD screen to attach them to the tank.

You are therefore free to place the probe wherever you like in the tank, and the suction cup prevents the probe from flying about in the water.

7. JW Pet Smarttemp Aquarium Thermometer

JW Pet Smarttemp Aquarium Thermometer
  • In-tank thermometer is secured with magnet outside the tank
  • No suction cups needed
  • Green safe zone indicates optimal temperature range
  • Large easy to read numbers

This aquarium thermometer by JW Pet is a very simple and easy to use model. It is 6 inches tall and an inch wide. It is very easy to read the temperature, as the liquid is red and the background is white. There is a useful green safe zone so you can quickly check if you are in the appropriate range.

There are two different units available; one is free standing and can be placed upright on the bottom of your tank, and the other can be attached via a magnet to the side of your tank. 

The free standing model is useful if you have a smaller tank, but as it is small it may get blown over by the current if you have a strong filter or an aquarium powerhead. The magnetic version allows you to move it easily to clean the glass.

The temperature reading is accurate to plus or minus 1.5 degrees Fahrenheit.

8. Cooper-Atkins Waterproof Reduced-Tip Digital Thermometer

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Cooper-Atkins Waterproof Reduced-Tip Digital Thermometer
  • Genuine OEM replacement part
  • Cooper Atkins has built a solid reputation as a leading manufacturer and provider of quality time, temperature, and humidity instruments
  • Uses OEM parts for safety, reliability, and performance
  • Approved by original equipment manufacturer (OEM)
  • Not intended for anything other than specified designed usage

You might not instantly think that this would be a useful thermometer for an aquarium, and you are right in that this unit by Cooper-Atkins is different to any other model on this list. 

It cannot be fixed permanently to an aquarium, and instead you need to take it out of the protective sleeve each time and dip the waterproof tip into the water. 

The reading is incredibly accurate though, and is very quick in giving the reading. So if your fish require a real narrow range this could be very useful. It is also very useful for when you are doing water changes. You need to ensure the water you use to fill up your tank is the same temperature, otherwise you can cause your fish to go into shock. Using this model is much easier than using other aquarium thermometers.

9. Jansamn Aquarium Thermometer Sticker Strip

Jansamn Aquarium Thermometer Sticker Strip
  • ★ Displays Degree Centigrade Fahrenheit ★ The thermometer strip has a range of 39℉ to 97℉ and 4℃ to 36℃. The large numbers are Fahrenheit and the small numbers are Centigrade
  • ★ Easy To Stick On ★ The Simply pulled the backing off to reveal the adhesive back and applied to the front of your fish tank/aquarium/carboy/jar/fermentation bucket. Great way to keep a quick eye on your fish tank/wine jar/kombucha temp
  • ★ Easy To Read ★ The thermometer strips is a piece of temperature sensitive paper.The colored marking shows the current temperature. If show multi-color,please choose the average value
  • ★ Kindly Tips ★ The best kombucha brew temp is 78℉ to 85℉.Keep your betta’s water between 78℉ to 80℉
  • ★ 100% Satisfaction★ We aim to provide the highest quality service and the best product quality for each customer. Place your order without any worry. If you have any question, please feel free contact us. We will unconditionally solve for you!

Very cheap and cheerful, this stick on best aquarium thermometer by Jansamn is extremely easy and simple to get started. Just peel off the backing to reveal the adhesive and stick it on your tank in the place you want it. 

This is a pack of four strips, so you can either place a couple at different parts of your tank if you want to see if the different parts of your tank are the same temperature, or you can keep them for if and when the adhesive fails on the first one.

Each strip has both Celsius and Fahrenheit, with Fahrenheit on the left and Celsius on the right. The range is from 4 to 36 degrees Celsius and 39 to 97 degrees Fahrenheit.  The Fahrenheit numbers are larger than those of the Celsius, which is good is you are still on imperial!

As with most stick on thermometers, the actual reading is green, with the upper limit in red and lower limit in blue.

10. Camway Aquarium Thermometer 

CAMWAY 2pcs Aquarium Thermometer Fish Tank Temperature Hygrometer Thermometer
  • 2-Pack Aquarium Thermometer can show temperature, humidity and time.
  • You can choose seither Fahrenheit or Celsius according to your need.
  • Temperature range -50 degree Celsius ~+ 70 degree Celsius,This aquarium thermometer is accurate to +/- 1℃.
  • 12-hour / 24-hour format and alarm clock function.The Large LCD display unit is easy to read,Small volume, large function.
  • Submerge probe into fish tank to measure water temperature.

You get a packet of two digital best aquarium thermometers if you get this from Camway. The model shows temperature, humidity, and time. You can switch between either Celsius or Fahrenheit depending on your preference. 

The large LCD screen is very easy to read and use, and you get a very high degree of accuracy, with the temperature shown being correct to 0.1 degree Celsius. The probe is put into the water to accurately measure the temperature.

The temperature range is very high so you can be sure that it will be able to measure the water temperature effectively. Having two units in the packet is very useful for if you have a larger aquarium.

The batteries you need are included, so you don’t need to worry about getting it set up. It is very easy to attach to your aquarium using the suction cup.

11. Marina Floating Aquarium Thermometer 

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Marina Floating Thermometer for Betta Fish Tank with Suction Cup, Aquarium Thermometer, 11201A1
  • Easy to read floating aquarium thermometer with suction cups
  • Includes a safety zone indicator appropriate for most tropical fish
  • Equipped with suction cups to attach to the side of your fish tank
  • Ensures your aquarium is at the proper temperature
  • Thermometer is 4.25 inches tall

Extremely cheap yet still functional and easy to use, this is the best aquarium thermometer by Marina which is perfect if you want something nice and simple.

This product is a floating thermometer, so is designed to be submerged in water. It has a suction cup so can be placed anywhere on the aquarium glass where you want the temperature taken.

Make sure you have this aquarium thermometer upright in the tank, as the liquid is at the bottom and rises to show the temperature. There is a green zone which is from 21 to 26.5 degrees Celsius, which is the optimum temperature for many freshwater and saltwater tanks. However be aware that your optimum temperature may be a little different. Each aquarium is unique after all!

The suction cup may slightly damage acrylic tanks when it is adhered to the side of the tank, so be a little careful. It can be a little hard to read the red liquid against the green background of the green zone, which is a little annoying, but it is a minor thing.

All in all this is one of the best aquarium thermometers for the price!!

Conclusion

Some fish, plants, and coral are very sensitive to temperature fluctuations and require a narrow range in which to flourish. To allow these organisms to be as healthy as they can be so you can enjoy them to the fullest you need a way of recording the temperature.

Hopefully this guide and reviews on the 11 best aquarium thermometers available at the moment have made it a little easier for you to see what you need for your tank, and which aquarium thermometer will be best for you.

There is a bit of give and take with aquarium thermometers, as each have their advantages and disadvantages. Digital aquarium thermometers are in general more accurate, so if you want one of these we recommend the Vivosun LCD Digital Aquarium Thermometer. It is a great choice and is very accurate and reliable.

If you would instead prefer a stick on aquarium thermometer we recommend the Capetsma Digital Touch Screen Aquarium Thermometer. There are no probes which will be unsightly in your tank, and the large screen is very easily read. This would be our recommendation for anyone wanting the best aquarium thermometer!

Capetsma Digital Touch Screen Aquarium Thermometer

About the author

Authority Aquarium Staff

Authority Aquarium Staff writers are experts and aquarium enthusiasts, our in-house marine biologist fact checks all our content and reviews to bring you the best advice for your aquarium health.

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