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Best Aquarium Thermometers: Our Top Picks 2024

The fish in your aquarium require the water to be at a relatively specific temperature, or else it may negatively impact their health. So you can easily monitor aquarium water temperature, a good aquarium thought thermometer is required. That’s exactly what I am here to help you find today, the best aquarium thermometer that the market has to offer.

Best Aquarium Thermometers

Top 5 Best Aquarium Thermometers

I’ve got five fantastic aquarium thermometers for you to check out, so let’s get started right away.

1. PAIZOO Fish Tank Digital Thermometer: Our Top Pick

PAIZOO Fish Tank Digital Thermometer Accurate LED Display to ±0.9°F Tank...
  • 👁️‍🗨️【HD LED Display】PAIZOO Aquarium Thermometer adopts LED screen to display...
  • 👆【Cordless & Touch Design】Stick-on Induction Thermometer senses water temperature through...

Here is a very simple yet effective digital aquarium thermometer. To mount it on the exterior of your aquarium, simply pull off the adhesive tab and stick it to the outside of your aquarium wherever you see fit. It allows you to easily place it in any area you prefer.

This aquarium thermometer features a temperature sensor on the backside, so it can accurately read the temperature inside of the aquarium. It is accurate to within 0.9 degrees Fahrenheit, which is actually very good. It even has a 5 second refresh speed, which means that it can quickly sense temperature changes.

This model comes complete with a relatively large LED display with large, bright, and green numerals. This makes it very easy to read no matter the time of day or night, or the angle you are looking at it from. You might also like how this unit is totally cordless, how it has great battery life, and how it is energy saving in nature.


  • Easy to mount
  • Very affordable
  • Accurate
  • Easy to read
  • 30 Day money-back guarantee


  • Hard to adjust position once mounted

If you are looking for a simple and affordable aquarium thermometer that is also accurate, this is probably your best option.

2. Memdern Aquarium Thermometer

Memdern Aquarium Thermometer Digital, Wireless Fish Tank Thermometer High...
  • 🐠【Large LCD Screen】Aquarium thermometer comes with a large LED screen, making it easier to...
  • 🐠【High Accurate Display】Temperature range:32℉~211℉;This aquarium thermometer is accurate...

Here we have another very simple aquarium thermometer that is designed to be mounted externally. All you have to do is remove the strip on the back to expose the adhesive, and then stick it to the outside of the tank wherever you see fit.

Just be aware that once you have it mounted, moving it will become very difficult, as the adhesive will likely not stick properly a second time.

This is however an extremely accurate aquarium thermometer, as the probe located on the backside can read the temperature to within 0.18 degrees Fahrenheit. Furthermore, it also has a very wide temperature range, ranging from 32 up to 211 degrees Fahrenheit. Of course, this should be more than enough for any aquarium.

This unit comes with the battery included, which means that it is also cordless, plus that battery can work for up to 12 months without having to be changed. You might also like the large and bright LED screen that is easy to read no matter the angle or time of day.


  • Easy mounting
  • Easy to see
  • Very accurate
  • Good price


  • Somewhat limited durability

Check out the Memdern Aquarium Thermometer if you need something simple that actually works!

3. AikTryee Water Thermometer

2-Pack Aquarium Thermometer, Fish Tank Thermometer, AikTryee Water Thermometer...
  • 【WIDE TEMPERATURE TEST】Fish Tank Thermometer Temperature Range -58℉ ~ +158℉; Temperature...
  • 【PRODUCT MATERIAL】Aquarium Thermometer uses a high-precision stainless steel sensor probe to...

This is actually a 2 pack of aquarium thermometers, which is nice, because if one breaks, you always have a backup.

What is important to note about this unit is that it is designed to be extremely accurate, which is thanks to the fact that it has an internal temperature sensor.

Although the display is mounted on the outside of your fish tank using an adhesive strip, the temperature sensor is attached to a cable, which you have to run to the inside of your aquarium and mount using an included suction cup.

This might not look as nice as a purely external aquarium thermometer, but it is much more accurate.

The temperature range of this aquarium thermometer is 58 degrees to 158 degrees Fahrenheit. The professional LCD display lets you easily see exactly how warm your aquarium water is, and it can be adjusted from Fahrenheit to Celsius if required.

There is a battery included here as well, which should last for around 8 months, plus it even comes with a spare battery.


  • Wide temperature range
  • Very accurate
  • Simple functionality
  • Good price
  • Durable build
  • Great battery life


  • Not the most visually appealing

If it’s an aquarium thermometer with fantastic accuracy that you are looking for, this is probably your best option on the list today.

4. JW Aquarium SmartTemp Thermometer

JW Aquarium SmartTemp Thermometer
  • We are proud to introduce the NEW SmartTemp Thermometer
  • This unique design combines a thermometer with a magnet

If you just want something extremely simple and affordable that gets the job done without breaking your bank, then this particular aquarium thermometer is probably the best option for you. Unlike all of the other options we have looked at so far today, this one is not digital.

This is a very simple old school thermometer that uses an expanding liquid with a temperature scale to provide you with 100% accurate temperature readings. 

Although it might not seem as high tech as a digital thermometer, this type of temperature reading is generally much more accurate.

One side of the thermometer features Fahrenheit and the other features Celsius, for easy reading. This is an internal thermometer, which means that you just place it right on the inside of the tank, and then use the included magnet on the outside of the tank to keep the unit in place. It really doesn’t get much simpler than that.


  • Extremely accurate
  • Super affordable
  • Fast and easy to mount
  • Nothing electronic that can break


  • Can be a bit hard to read

This is a great item to consider for anybody who likes old school thermometers.

5. Marina Deluxe Floating Thermometer with Suction Cup

Marina Deluxe Floating Thermometer with Suction Cup
  • Aquarium Accessory: With water temperature being such a critical factor for the well-being of fish,...
  • Ideal Temperature Range: Includes a safety zone indicator range for most tropical fish.

Here we have another very simple analog aquarium thermometer, as opposed to a digital one. I personally love analog thermometers, because there isn’t anything electronic included, so there aren’t nearly as many breakable components.

Furthermore, although digital thermometers may look very nice and are very easy to read, they also aren’t always the most accurate.

This is opposed to an analog or expanding liquid thermometer such as this one, which tend to be extremely accurate.You usually never have to worry about inaccurate temperature readings with a thermometer like this one. 

I also like how one side features Celsius and the other features Fahrenheit, so you can easily read the temperature no matter whether you use the imperial or metric system.


  • Simple but effective
  • Celsius and Fahrenheit
  • Easy to mount
  • Very affordable
  • Durable and long-lasting
  • No batteries required


  • Can be difficult to read in dark light

If you just want to spend a few dollars on a basic aquarium thermometer that gets the job done just fine, then this is always a good option to consider.

Aquarium Thermometers Buyers Guide: What to Look Out For

Before we call it a day, let’s quickly talk about some of the most important considerations when purchasing an aquarium thermometer.

The Type

You always want to consider the differences between digital thermometers and much older analog or expanding liquid thermometers. 

Digital thermometers may be a bit easier to read and simple to operate, although they also tend to be a little less accurate than thermometers that use an expanding liquid.

Digital thermometers will usually also be a bit more expensive due to their functionality. Just make sure that if you go for an expanding liquid thermometer, that you do not choose one that still uses mercury, although those are now fairly rare.

Internal vs External

You always want to consider the differences between internal and external thermometers, which generally only applies to the digital variety. 

Internal aquarium thermometers still have the display on the exterior, but also have a temperature probe that you have to run to the inside of the tank.

These tend to be much more accurate than external thermometers that use an external sensor which try to sense the temperature through the glass, but they also don’t look as nice because you have a wire with a probe on it running from the outside to the inside of the tank.


If you want the most accurate option around, going for an analog or expanding liquid internal thermometer is probably best.

thermometer in the aquarium

However, there are also digital thermometers that can be extremely accurate. Whatever the case may be, always pay attention to the accuracy range as indicated by the product in question.


The vast majority of aquarium thermometers amount to either the inside or the outside of the tank using simple suction cups. 

However, as you can see from the reviews above, there are some models that may use other methods such as magnets. It really depends on what your own personal preferences are.

Ease of Viewing

If you want a thermometer that is very easy to read no matter the time of day or viewing angle, then I do recommend going for a digital thermometer. Those bright numerals tend to be fairly easy to read.