Best Aquarium Thermometer

Every aquarium needs a reliable thermometer. This is especially true if you like to keep tropical fish, as you will need to constantly monitor the temperature within the tank to make sure that the water is a comfortable environment.

So, you’re looking to add a new thermometer to your tank. But how do you know you’ve found the best aquarium thermometer? We’ve taken a look at multiple thermometers across the market to find the best and most accurate one to add to your aquarium.

How do you know what to look for in an aquarium thermometer? What factors do you need to consider before investing in one? Which is the best type of aquarium thermometer to buy?

Not to worry - we’ve collated all that information in our handy buyer’s guide so that you’ve got all the information you need to stay reliably informed. We’ve even put together a few frequently asked questions to satisfy your burning queries!

Short on time? Check out our top pick of all the aquarium thermometers below!


The Zacro LCD digital aquarium thermometer is a convenient way to check on the temperature inside your tank to ensure that your fish are able to thrive.

This particular probe thermometer is easy to use; simply pop the probe part of the device into the water, and read the temperature measurement on the LCD screen.

The Zacro thermometer can be attached to the front of your aquarium, placing the probe part of the device in the water to monitor the temperature. That means it won’t take up large portions of your aquarium, and you can use it as and when you need to.

Shows you a wide range of temperatures, so you can rest assured that the measurement is accurate. You can also choose between Fahrenheit and Celsius depending on your preferences.

This particular aquarium thermometer is battery operated. Simply pop in the LR44 battery and it will be ready to use!


  • Easy to use in your aquarium.
  • Battery operated.
  • Shows you accurate temperatures to within 1 degree.
  • Attach the display monitor to the front of your aquarium to monitor the temperature regularly.
  • Shows a wide range of temperatures as needed depending on your aquatic environment.


  • While the general consensus is that this is a good, accurate thermometer, some customers found the readings became less accurate over the years.


The Marina floating thermometer is an easy to read thermometer that can be attached to the glass of your aquarium with the included suction cup.

This particular thermometer includes a safety zone to show the most appropriate temperature for your tropical fish.

You can easily monitor your aquarium’s temperature with this easy to use thermometer and ensure that the water is at the appropriate heat level for your fish.

Specially designed to float in a vertical position so as to make it easier for you to get an accurate reading.

The Marina floating thermometer will display temperature in both Fahrenheit and Celsius so as to give you the choice of readings you wish to use.


  • Designed to remain upright in your aquarium.
  • Suction cup included to attach the thermometer to the glass of your tank.
  • Displays temperature in both Fahrenheit and Celsius.
  • Comes with a safety zone to show the ideal temperature.
  • Easy to use.


  • Some customers had issues with the suction cup not sticking to the side of the glass.


The Cooper-Atkins DFP450W-0-8 digital thermometer may not be specifically designed for use in an aquarium, but the super accurate temperature readings make it a must buy for any budding enthusiast.

Simply hold the tip of the thermometer in your aquarium water for five seconds, and you’ll have an accurate reading.

This particular thermometer is waterproof and will survive the occasional dunking if you accidentally drop it into the water.

The Cooper-Atkins thermometer comes with an alarm function to alert you once the optimum temperature has been reached for your tank.

The small handheld device means it won’t take up loads of room in your aquarium, leaving you plenty of space for more fish or other accessories.


  • Easy to use handheld device; simply hold the tip in the water for five seconds.
  • Highly accurate readings, making it a good alternative to other probe thermometers.
  • Fully waterproof, and will survive being accidentally submerged in water.
  • Comes with an alarm function to show you when the optimal temperature has been reached.
  • Won’t take up valuable space in your aquarium.


  • As this is a handheld device, you will need to take it out to use it regularly, as opposed to units specifically designed with aquariums in mind which you can leave in the water.


The Inkbird ITC-308 digital temperature controller is the deluxe option when it comes to measuring temperature. You can attach this to your cooling and heating equipment so as to ensure that the water temperature is always correct for your fish.

You can choose to read the temperature measurements in either Fahrenheit or Celsius depending on your preference.

This particular device comes with a dual display feature so that you can see both the measured temperature and the set temperature at the same time.

The easy to use design means this particular temperature controller will be simple to use regardless of your experience with thermometers.

A variety of alarms are available with this equipment so that you can monitor any radical temperature changes.


  • The deluxe option for managing your aquarium’s temperature.
  • Choose between Fahrenheit and Celsius temperatures.
  • Dual display feature to show current temperature as well as set temperature.
  • Easy to use.
  • Comes with a variety of alarms to alert you to sudden changes in temperature.


  • As it’s not specifically designed with aquariums in mind, it might be a tad more complicated to use than some of the other options on our list.


The LCR Hallcrest A-1005 LCD sticker thermometer is easy to use. Simply attach to the glass of your aquarium, and the strip will change color to indicate the temperature in your tank.

You can easily move the sticker thermometer around the glass of your aquarium if you need to change its location.

Doesn’t require any batteries or other source of electricity to work, so there’ll be no chance of any unfortunate accidents.

The LCD thermometer is the perfect affordable option for those working on a budget.

This sticker thermometer is easy to use and easy to read, so you’ll know you’re getting accurate readings within 1 or 2 degrees.


  • Easy to use; ideal for beginners.
  • Simply attach to the outside of your aquarium to use.
  • Doesn’t require batteries or electricity.
  • Easy to move after it’s been installed.
  • Affordable if you’re working to a budget.


  • This won’t be as accurate as some of the digital options available on the market.

Best Aquarium Thermometer Buying Guide

No matter whether you're the more casual hobbyist or a dedicated aquarist, you’ll know the merits of having a thermometer in your aquarium. If you’re keeping tropical fish, you’ll want to make sure that the water in your tank is set to the optimum temperature, so that your fish can thrive.

But what factors should you consider when choosing the best aquarium thermometer? How many different types of thermometer are there, and which one is the best thermometer for your particular aquarium? 

Not to worry - we’ve put together a list of the few things you should look out for when searching for the best aquarium thermometer. You’ll want to think about all of these factors before shelling out for your new thermometer, so don’t be tempted to just buy the first one you stumble across.

Read on to find out all the things you need to think about before you commit to buying a thermometer for your aquarium!

Type of Thermometer

There are three main types of thermometers available on the market. These are the digital thermometer and probe, the submersible thermometer, and the thermometer sticker strips. There are benefits and downsides to all of them - it’s important to consider what you hope to gain from your thermometer when deciding on the right one for you.

Digital thermometers and probes are separated into two different units that combine together to show you accurate readings. These are generally considered to be the most accurate of the three main types. 

The probe part of the thermometer will be submerged in the water, where it can take accurate readings, and are attached to the display part of the console which will show you the measurement. These come as either a wired probe or a fixed probe - fixed probes need to be handheld, but wired probes can be left in the water at all times.

These types of thermometers are easy to read, easily moveable, and take up much less space in your aquarium. They can be more expensive depending on the model you opt for - more advanced versions can come with alarms.

Submersible aquarium thermometers tend to be analog and come in two types - those that float freely around your tank, and those that can be attached to the side of the tank using a suction cup. These are designed to remain in the water at all times and are hands-free for ease of use.

These particular types of thermometer can be more complicated to use as if they’re not fixed to the glass of your tank as they will bob around the water at any movement. The analog method may be more confusing to measure than the digital method, too.

The last of the three different types of thermometers - sticker thermometers - are generally considered to be the least accurate. They’re easy to use and are definitely the cheaper option of the three, but these sit on the outside of your tank - so they’re not going to be as accurate as thermometers that sit in your tank permanently.

Analog vs Digital

There are two main methods of measuring temperature - analog and digital. Analog is considered to be the more archaic of methods, as you’re having to measure the liquid inside the thermometer against the meter to get an accurate reading.

In complete contrast, digital thermometers will be able to show you an accurate measurement instantly, and with a lot more precision. These also tend to be constructed with plastic, so you won’t have to worry about smashed glass in your aquarium if they break.


The most important factor to consider is how accurate the measurements are. There’s little point in opting for the cheapest or easiest option if it’s not accurate - you’ll want to make sure that you’re putting the needs of your fish first.

Check out the reviews to see what other customers think of the thermometer’s accuracy. The more accurate the thermometer, the less you’ll have to worry about adjusting your heater or cooling equipment to match the temperature your fish need.

Power Options

Some people feel uncomfortable with putting a unit that requires batteries or electricity into their tank because - quite simply - water and electricity don’t mix. If you fall into the same camp, you might want to consider checking out the range of submersible thermometers available.

That being said, it’s going to be a rare event where something goes wrong to the point where it will potentially damage your fish. You can get digital thermometers with probes that sit in the water, while the console remains on the outside of your tank - that way you’ll know there’s no risk to your fish.


You’ll want to choose a thermometer for your aquarium that is durable and will stand the test of time. Take a look at what other customers had to say of the finished product when they received it, and see how long theirs have lasted. 

You’ll also want to take a look at the materials that have been used to construct it so as to give yourself a better indicator of how long the thermometer will last in your tank.

Ease of Reading

The best thermometer for your aquarium will be one that you can easily read. Be mindful of the fact that analog thermometers will require a bit more concentration to read accurately than digital thermometers will. The harder to read your chosen thermometer is, the more annoying it will get over time.

Also consider where in your tank the thermometer will sit. If you hide it towards the back of your aquarium, it’s not going to be easy to spot at a glance. 

Materials of Construction

The vast majority of thermometers will be constructed either with plastic or glass. For the type of thermometer that will sit in your aquarium permanently, you’ll have to consider the merits of each material.

Glass thermometers are not the ideal choice if you have aggressive fish that might go for them. If the glass smashes inside the tank, you’ll have to deal with any consequences that could arise from that - no matter how unlikely it is. 

Several of the submersible analog thermometers will also have things like alcohol included as part of their makeup so as to provide you with accurate readings. How would that affect your fish if the glass were to break and release it into the water?

Plastic thermometers are less likely to cause damage to your fish once broken, but you may have to consider the source of power as a factor in the case that these fail. How will this affect your aquarium?

Think over the benefits of each type of thermometer and the likelihood of something going wrong inside the aquarium when deciding which option to invest in.

Ease of Use

There’s no point investing in the finest thermometer for aquariums that money can buy if it’s far too complicated for you to use. Think about how often you’ll want to measure the temperature. 

Do you want one you can check at a moment’s notice? Or one that takes up less room? You’ll most definitely want one that will show you all you need to know at a glance, rather than have to decipher for ages.

One sure fire way to check how easy the thermometer is to use before you commit to buying it is to check out what the other customers think in the reviews.

Frequently Asked Questions

Which kind of thermometer is most accurate?

Out of the three main types of thermometers designed for use in the aquarium, the digital thermometer with probe is widely considered to be the most accurate. That’s because the probe can be placed anywhere within your aquarium to get an accurate reading, and the handheld console will be able to show you the exact measurement taken.

Where is the best place to put a thermometer in a fish tank?

The ideal place to put your thermometer for a truly accurate reading is just above the gravel line. This will show you the most accurate temperature of the water. It’s important to be mindful of the fact that the closer to your heater you place the thermometer, the higher the temperature reading will be. Floating and standing thermometers should be put on the opposite side of the tank to your heater.

What temperature should a fish tank be at?

For most fish, the ideal temperature to keep your fish tank at is between 75 to 80 degrees Fahrenheit. However, if you’re only keeping one or two different fish in your tank, it’s best to research their individual preferred temperatures to see that you’re able to offer them their optimal environment.