The Best Aquarium Thermometers (2021 Reviews)

Skylar Dial
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Whether you are a first-time fish keeper or an experienced professional, the temperature of your aquarium matters. Many fish and aquatic species are intolerant of spikes or dips in temperature, and without the proper maintenance of your aquarium, dangerous disturbances in your aquarium’s temperature can easily occur.

Because of this importance, your aquarium needs an aquarium thermometer to monitor the temperature of the water. Most thermometers for the aquarium come in the form of a digital probe or a floating glass stick.

Two popular choices are the liquid crystal thermometers or electronic thermometers. There are advantages and disadvantages to both types. We cover them thoroughly below.

But I won’t delve too deeply into the details of how aquarium thermometers work and things like the benefits of dual sensors or how glass bulb thermometers work, which are explained well in this article by Reef Central.

Also, these are the best aquarium thermometers for freshwater or saltwater tanks.

If you want to learn more about the reef aquarium hobby and in particular, learn what type of aquarium and fish you should use on your reef tanks, be sure to check out our Ultimate Guide to Reef Aquariums.

Here are my reviews for the best aquarium thermometers for your reef tank.

NameCategoryProduct
Cooper Atkins DFP450W Digital Pocket Test Waterproof PartBest OverallCooper Atkins DFP450W Digital Pocket Test Waterproof Part
Mundopet Floating ThermometerBudget PickMundopet Floating Thermometer
Lifegard Aquatics Digital Temp AlertUpgrade PickLifegard Aquatics Digital Temp Alert

1. Cooper Atkins DFP450W Digital Pocket Test Waterproof Part

Our rating: 9 / 10

Cooper Atkins DFP450W Digital Pocket Test Waterproof Part

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Pros:

  • Large, easy to read numbers
  • Easily readable from a distance
  • Comes with a suction cup and a string so you can hang it up
  • Accurate to within one degree
  • Waterproof

If you dread checking your tank temperature, then this handy pocket thermometer is for you. It’s a small, portable device that measures the water temperature, while the device itself stays cool to the touch.

There’s a built-in fish icon that lets you know if a sudden temperature drop is ok, but you may want to check on your fish just in case.

2. Zacro LCD Digital Aquarium Thermometer Fish Tank Water Terrarium Temperature

Our rating: 9 / 10

Zacro LCD Digital Aquarium Thermometer Fish Tank Water Terrarium Temperature

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If you’re one of those people who tend to go overboard when it comes to researching products, then this thermometer might be for you. The completely digital Zacro aquarium thermometer has an 800-degree Fahrenheit range that makes it great for finding the right water temperature for your fish. It’s also easy to read, and has a large LCD screen.

As far as features go, the Zacro aquarium thermometer has a dual probe that allows for precision reading. It’s also calibrated to meet marine and freshwater needs. This means you’ll get an easy-to-use product that’s suitable for all water temperatures.

The only downside is the suction cups. There are a handful of complaints that say the cups don’t work, and it’s hard to position the thermometer where it should be.

3. LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer

Our rating: 8 / 10

LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer

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Pros:

  • Easy To Read
  • Accurate
  • Small Analog Size Perfect For Small Tanks

Cons:

  • The Temperature Seems Large In General But It’s Not
  • The Temperature Gauge Line Is Kinda Small
  • 30 Seconds To 1 Minute To Read

After carefully considering all factors for the purposes of this article, our top pick for the best aquarium thermometer is the LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer. With well over 2,000 reviews and a 4.8 out of 5 star rating on Amazon, we were happy to include this model into our list.

Trusted by many as being an extremely reliable and accurate thermometer, this probe style thermometer can accurately measure the temperature in both Celsius and Fahrenheit at the same time. The backlight provides excellent visibility in both light and dark environments, no matter if the sun is shining through the window or if you’re keeping your lights on overnight.

What we really liked about this model is the reliability. In the two weeks that we used it, we noticed no battery drain, and there were no instances where the readings fluctuated between runs.

4. Marina Floating Thermometer

Our rating: 8 / 10

Marina Floating Thermometer

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Part of your responsibility as a fishkeeper includes monitoring water temperature. For this kind of task, we’d recommend you this Marina-floating thermometer which records the temperature in your tank in both Celcius and Fahrenheit.

What’s great about this thermometer is that it is completely waterproof, even if you submerge it in your tank. Another good thing about this one is that it comes with a suction cup which you can use to attach it to your glass tank, giving it a long period of time before it starts to deteminate.

When you’re looking for digital aquarium thermometers, you’ll have a hard time finding one as good as this one. Not only does it have an easy-to-use LED display, it also has the temperature readings back, which is useful especially if you want to measure the overall temperature of your tank in a short time period.

5. Aquarium Thermometer

Our rating: 8 / 10

Aquarium Thermometer

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Without Ice.

Aquarium thermometers are often overlooked by aquarium owners. This is something aquarium owners should really take some time to research. As a tank owner, it’s your responsibility to make sure your aquatic friend is comfortable and their environment is optimal. In the case you were unaware, fish need a certain temperature to survive and thrive. A quality aquarium thermometer should be considered essential for every fish tank.

For new aquarium owners, we’ll begin with the basics. Fish need two main things: oxygen and water temperature. The latter has a big impact on the former. Higher water temperature creates a higher oxygen demand, and a lower water temperature creates a lower oxygen demand. In the case of the Betta, their oxygen demand is a bit higher than other aquariums.

6. MarsAqua Dimmable 165W 300W LED Aquarium Light Coral Reef Light Full Spectrum

Our rating: 8 / 10

MarsAqua Dimmable 165W 300W LED Aquarium Light Coral Reef Light Full Spectrum

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Pros:

  • Available at 165w, 300w, 360w and 460W
  • The lights are super bright and efficient
  • Reasonably priced
  • They consume less energy; making it cost-efficient as well
  • It has a low heat generation, which means that your fish won’t feel anything
  • It has a dimming options, and a rotating and locking base
  • The lights are well-made and durable
  • Ideal for marine aquariums as well as freshwater
  • Comes with a warranty
  • Efficient heat insulation, which means you can place it nearby the aquariums

/Lion Fish/Coral/Clown Fish/Bud/Anemone/Frog/Snails/Sea Shell, Ultra Bright.

7. Lifegard Aquatics Digital Temp Alert

Our rating: 8 / 10

Lifegard Aquatics Digital Temp Alert

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Though the Aquarium Digital Temp Alert is a little pricier than most other thermometers, it’s also a highly accurate temperature reader.

With a range of -50-120 degrees, it can easily monitor your aquarium’s temperature.

It’s also quite accurate with a reading of +/- 0.1 degrees Celsius. This can be extremely useful for Betta – as they thrive in a temperature range between 76 to 86 degrees.

8. Fluval Wireless 2in1 Digital Thermometer

Our rating: 8 / 10

Fluval Wireless 2in1 Digital Thermometer

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Best Aquarium Thermometer for Stocking

This thermometer is a great choice for anyone who is in the market for a versatile and functional thermometer. It’s a combination of both an aquarium thermometer and a room thermometer.

Since it’s a smart thermometer, you can use it to track the temperature of your tank as well as the room your aquarium/pond is in. It’ll send real time updates too your phone so you can keep an eye on your tank while you’re on the go.

9. Zoo Med Digital Thermometer

Our rating: 8 / 10

Zoo Med Digital Thermometer

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Pros:

  • Clear and easy-to-read
  • Cheap and affordable
  • Floating design – no need to place it at the bottom of the tank
  • Can be used to measure the water temperature outside of the tank
  • Runs on two AAA batteries

Cons:

  • The large letters could be too big for your tank
  • The probe doesn’t stick to the glass pane
  • The LCD display could be too bright
  • The readings taken are only accurate to +-2 degrees

W/ Probe, Floating.

The Zoo Med Digital Thermometer floats in your tank, which makes it easier to read the temperature without having to retrieve it from the tank.

This thermometer can also be used outside of the fish tank to measure the ambient temperature of your home or office. This can be really handy if you are trying to figure out how much heat your fishes need.

10. SUKRAGRAHA Traditional Stick-on Aquarium Thermometers Temperature Strip Celsius Fahrenheit Display 10 pc

Our rating: 8 / 10

SUKRAGRAHA Traditional Stick-on Aquarium Thermometers Temperature Strip Celsius Fahrenheit Display 10 pc

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Pros:

  • Has a very sticky adhesive back
  • Very easy to apply
  • Comes in a variety of colors
  • Very cheap
  • Comes in a pack
  • Seems to work better than digital thermometers

Cons:

  • Some bad reviews stating that the adhesive doesn’t stick
  • Small and doesn’t cover the whole tank

The good old traditional stick-on thermometer seems to be the best aquarium thermometer for freshwater fish. These stick on thermometers will help you monitor your tank temperatures while also not breaking the bank.

The SUKRAHGA stick on thermometers are readable in both Celsius and Fahrenheit.

SUKRAHGA Aquarium Thermometers Package Quantity:10 (1~7.50 Celsus / 9.5~25.500 Fahrenheit)

11. Penn-Plax Standing Thermometer

Our rating: 8 / 10

Penn-Plax Standing Thermometer

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Pros:

  • Highly accurate
  • Can be quickly and easily read thanks to the large temperature display
  • The temperature range/unit selection is highly convenient
  • The thermometer features the float option, which eliminates any errors that may be caused by water currents
  • Solidly built
  • Good range of colors – white, blue, yellow, green
  • Has an 8-inch arm
  • Small in size, so it’s easy to store (and even store in the water without affecting the reading much)

Cons:

  • You have to manually make sure that the thermometer is floating
  • Doesn’t measure the temperature of the water directly, but rather the air surrounding it

The Penn-Plax Thermometer stands out greatly due to its accurate readings. For the most part, you don’t have to worry about any of its reading being affected by the temperature of the air around it.

This thermometer basically shows you the temperature of the water. The thermometer features an adjustable arm so that you can easily read the temperature.

But, the ambient temperature must be higher than the temperature of the water you’re trying to measure for the thermometer to work accurately. With that said, its ideal for any size aquariums.

12. HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control

Our rating: 8 / 10

HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control

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(Glass or Acrylic Tank)

13. American Thermal Horizontal Aquarium Thermometer

Our rating: 8 / 10

American Thermal Horizontal Aquarium Thermometer

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Pros:

  • Accurate and reliable
  • Easy to read
  • Simple, single-button operation
  • Solid construction
  • No batteries required

Cons:

  • The display is not back-lit, so difficult to see in darker environments.

(For 5-20 Gallon)

Testing out temperature isn’t always easy. So, it’s nice to have an aquarium thermometer that provides fast and accurate readings for your tank. The American Thermal Aquarium Thermometer is easy to use and read. It’s also easy to attach to any aquarium. The thermometer has a glass tube that’s approximately 1.78 inches in diameter. The thermometer is meant to be placed on the outside of your aquarium. This is to make it easy for you to read. The thermometer can be attached to the aquarium using a suction cup.

This thermometer is designed to measure the temperature of a 5-20 gallon aquarium. It has an adjustable suction cup that can be moved around by adjusting the stainless steel lever. The suction cup’s measurements are from 2.5 to 4 inches.

14. American Thermal Horizontal Aquarium Thermometer

Our rating: 8 / 10

American Thermal Horizontal Aquarium Thermometer

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Pros:

  • Accurate and reliable
  • Easy to read
  • Simple, single-button operation
  • Solid construction
  • No batteries required

Cons:

  • The display is not back-lit, so difficult to see in darker environments.

(For 5-20 Gallon)

Testing out temperature isn’t always easy. So, it’s nice to have an aquarium thermometer that provides fast and accurate readings for your tank. The American Thermal Aquarium Thermometer is easy to use and read. It’s also easy to attach to any aquarium. The thermometer has a glass tube that’s approximately 1.78 inches in diameter. The thermometer is meant to be placed on the outside of your aquarium. This is to make it easy for you to read. The thermometer can be attached to the aquarium using a suction cup.

This thermometer is designed to measure the temperature of a 5-20 gallon aquarium. It has an adjustable suction cup that can be moved around by adjusting the stainless steel lever. The suction cup’s measurements are from 2.5 to 4 inches.

15. JW Pet Company Smarttemp Thermometer Aquarium Accessory

Our rating: 8 / 10

JW Pet Company Smarttemp Thermometer Aquarium Accessory

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Aquarium thermometers are a must-have for any seasoned aquarist. But with the many different types available on the market, choosing the best aquarium thermometers can be a daunting task.

That’s why we’ve tested the most popular types available, so you don’t have to waste valuable time in searching for the right ones. And based on our own experience, as well as the feedback from fellow fish keepers, we’ve selected the best aquarium thermometers that you can buy right now.

Before anything else, it’s important to understand what a good aquarium thermometer should be able to do for you. A reliable thermometer makes it easier for you to keep tabs on things like water temperature, aquarium humidity, and tank decor.

16. Penn Plax Floating Aquarium Thermometer

Our rating: 7 / 10

Penn Plax Floating Aquarium Thermometer

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17. Fluval Nano Thermometer

Our rating: 7 / 10

Fluval Nano Thermometer

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The Fluval Nano seems to have taken everything into consideration when they designed this thermometer, which includes both visual and audible alerts. That way, no matter what you’re doing in your venue, you’re still going to know when the water temperature changes drastically.

If you’re new to aquariums, this thermometer could be a great start. Ideally, it should be placed in the center or the back of the aquarium to ensure that it’s not disturbed.

18. Amer Thermal Instruments Liquid Crystal Vertical Aquarium Thermometer

Our rating: 7 / 10

Amer Thermal Instruments Liquid Crystal Vertical Aquarium Thermometer

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Pros:

  • Very accurate
  • Wide range ensure you choose the right product for your use
  • Uses fluid or air to determine the temperature
  • Easy to install
  • Can tell you the water temperature at a specific point above the water

(AA-200YE)

In the professional world of aquarium keeping, there’s one name that stands out among the rest. And that name is Amer.

The Amer name is trusted and respected by the professionals for having some of the best aquarium thermometers on the market.

19. VEE GEE Scientific 83110 Ultra High Accuracy Digital Thermometer

Our rating: 7 / 10

VEE GEE Scientific 83110 Ultra High Accuracy Digital Thermometer

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The VEE GEE 83110 is an inexpensive and easy to use aquarium thermometer. Unlike many others, the temperature of the aquarium is displayed – rather than the barometric pressure.

It features a waterproof design that is very easy to use. Because of the size, it is suitable for smaller aquariums – ideal for home hobbyists with one or two fish. The measurement range is -58.0 Degrees F to 230.0 Degrees F (-51.1 Degrees C to 110 Degrees C).

The low reading range of the VEE GEE 83110 makes it ideal for use with amateur hobbyist, and low-maintenance fish. However, people who are looking for more accurate reading should consider a different thermometer.

20. Zoo Med Submersible Digital Nano Therometer

Our rating: 6 / 10

Zoo Med Submersible Digital Nano Therometer

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We especially love the fact that the thermometer can measure both water and air temperature. That’s because the water temperature can affect your air temperature, so keeping the difference between the two measurements minimal will ensure your Betta lives in the best environment possible.

The thermometer is battery operated and works by measuring the temperature in Celsius and Fahrenheit. It’s safe to use, as the outside of the thermometer is water-resistant, but it’s not intended to go completely underwater. If you want to measure the water temperature, you can place it inside your tank, by attaching it to the wall, for example.

If you really want to dig in to your Betta's lifestyle, we recommend buying a thermometer. We recommend this Zoo Med aquarium thermometer, as it can be both used for your water and air temperature.

21. uxcell 18 to 34-Degree C Plastic Fish Tank Thermometer Sticker

Our rating: 6 / 10

uxcell 18 to 34-Degree C Plastic Fish Tank Thermometer Sticker

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Pros:

  • This plastic fish tank thermometer can be stuck directly on the glass.
  • The temperature is easy to read because the thermometer is 3” in length.
  • The sticker has 3 lines that reads 4-D, 4-D, and 32-35-D.
  • The sticker is made of high quality vinyl plastic that won’t damage the glass or tank.
  • This thermometer is is great for freshwater tropical fish tanks.

Cons:

  • It is not a traditional thermometer that you can stick on a wall.
  • This is a sticker that only tells you the temperature of the tank, not the room.
  • You have to look at the sticker to get the temperature.

(Aquarium Stickers)

With the arrival of Spring, it’s time to take a closer look at your aquarium temperature. Most fish are sensitive to temperature and oxygen levels. If you notice lazy behavior from your fish, there’s a good chance that the temperature is too cold for them.

22. American Thermal

Our rating: 5 / 10

American Thermal

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Looking for a thermometer with great accuracy? If so, the American Thermal Aquarium Vertical Thermometer is a great choice. It comes with an easy to read easy-to-read glass tube that runs along the middle of the thermometer. This is perfect for smaller tanks, because you can easily see the temperature even at the other end of the aquarium.

This thermometer comes with a clear glass cover, which is good for a few reasons. It’s scratch resistant, so you won’t have to worry about any damage. The thick glass also provides good energy efficiency. The glass offers resistance to energy penetration, so you won’t have to worry about it getting damaged by direct sunlight.

23. TAAM Rio Aquarium and Pond Floating Thermometer

Our rating: 5 / 10

TAAM Rio Aquarium and Pond Floating Thermometer

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The TAAM Rio is an economical thermometer suited for both aquariums and ponds. It comes in a white theme, a fancy black theme or a fancy blue theme – this gives you three different options to match your setup.

If you’re looking for a 2-3 hour response time, this thermometer is for you.

The TAAM Rio is efficient in design and very accurate; it even has an overload protection.

24. Mundopet Floating Thermometer

Our rating: 5 / 10

Mundopet Floating Thermometer

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Pros:

  • Using thermometers is an important way to know the needs of your fish and act accordingly
  • Fast and responsive temperature reading
  • Comes with suction cup – it attaches to the tank wall for easy reading
  • Small size – it can fit inside the tank
  • Easy to read temperature numbers
  • Sleek design

Cons:

  • The thermometer may seem to get stuck to the wall since it’s too close to the tank bottom
  • It’s not that durable – some users have complained that the thermometer broke inside the tank

Here’s a simple yet effective thermometer made for fish bowls, koi ponds and aquariums. With a compact design, this thermometer is easy to read because it has large temperature figures. The temperature range goes from -10 to 104F with the Fahrenheit to Celsius scale.

This thermometer is made with an LCD digital screen, it’s a very popular type of thermometer as it’s not only accurate but also very fast in measuring the water temperature. The screen is white and the thermometer is black in color – and it’s highly durable. With proper handling the thermometer should last a few years.

25. pranovo 5 Pack Floating Thermometer Waterproof Temperature Gauge

Our rating: 3 / 10

pranovo 5 Pack Floating Thermometer Waterproof Temperature Gauge

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Pros:

  • Constructed of shatterproof plastic
  • Relatively inexpensive
  • Does what it’s supposed to do
  • Doesn’t give a false reading

Red.

The Pronovo floating thermometer does exactly what it says it does. To test it out, we put it inside some water. It didn’t move at all. It will be a great addition to your tank if you’re having trouble finding a good spot where the current doesn’t move the thermometer constantly. This one will work.

There are other products that include an alarm, but the problem with those is that you might not hear it. This one doesn’t have that problem as it has a loud alarm, but not so loud where it’s annoying. Most people will hear it over the sound of the filter.

26. Taam Stick On Thermometer Reads Between 64-93 Degrees F

Our rating: 3 / 10

Taam Stick On Thermometer Reads Between 64-93 Degrees F

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The Taam Thermometer is a small yet reliable thermometer that’s ideal for monitoring your water temperature.

To use it, you simply have to peel off the back of the thermometer and stick it onto the side of your aquarium. Since it measures the temperature on the outside of the aquarium, it will measure the temperature in your fish tank instead of in the water.

To measure the temperature, simply match your aquarium temperature with one of the pre-marked temperatures on the thermometer, then take your measurement.

Frequently Asked Questions (FAQ)

What is the most accurate aquarium thermometer?

This is a surprisingly difficult question to answer as there are so few aquarium thermometers that are designed specifically for aquariums.

The two most accurate thermometers I have found are the ColorpHast thermometer and the AquaBasics thermometer.

Which kind of thermometer is most accurate?

There are 3 types of thermometers which would be the most accurate.

{1}. Digital Aquarium Thermometer
{2}. The Specific brand that is labeled for it.
{3}. The aquarium thermometer with a glass bulb

Digital is the most accurate and easy to use. However, it could be tricky to find the exact right spot under the water where it sits.

The second one is a specific brand thermometer. Depending on the brand the thermometer could be more accurate than the other.

The third would be the glass bulb thermometer. If you want to be sure you have the most accurate one, then this is the option you would want to go with.

Which aquarium brand is the best?

There are so many different types of fish tanks available on the market, and of course, there is a wide variety of prices too.

So how can you expect to know the best fish tank available? Well luckily I’ve been trying to figure this out for years and I’ve seen quite a few different aquariums. I believe there are three things people should look for when buying an aquarium.

The first thing to look for is size. If you are new to owning a fish tank, don’t go too big too soon. Starting off small allows you to get used to owning a fish tank and it helps you gain experience with taking care of it.

Are aquarium strip thermometers accurate?

While a bulk of aquarium thermometers are accurate, there are some factors to be aware of so as to obtain as close to a correct reading as possible. The main factor that may be off is the conversion or the transfer from Celsius to Fahrenheit, especially for those who may not be all that great at conversions and have a hard time remembering how to convert.

There is now a growing demand for thermometers that can be placed inside the tank that will communicate with your mobile device via Bluetooth or Wi-Fi. They will feed your device with an exact temperature reading. In this regard, they can be a bit more expensive than the traditional stick-on ones.

Conclusion

It may seem surprising that the best aquarium thermometer is not your average/cheap stick-on thermometer. But they’re generally inaccurate and only provide a rough guide of the temperature of the tank water.

The best digital aquarium thermometer are expensive, but they’re more accurate than basic stick-on thermometers. They will also help you to have a better idea of the temperature the fish are experiencing.

They come with a range of features, benefits, and drawbacks that should be keeping 12 considerations in mind when buying your best aquarium thermometer.

This article is going to review the best aquarium thermometers by comparing:

Our Recommendation

NameCategoryProduct
Cooper Atkins DFP450W Digital Pocket Test Waterproof PartBest OverallCooper Atkins DFP450W Digital Pocket Test Waterproof Part
Mundopet Floating ThermometerBudget PickMundopet Floating Thermometer
Lifegard Aquatics Digital Temp AlertUpgrade PickLifegard Aquatics Digital Temp Alert