Best Aquarium Thermometer – Review & Guide

One crucial part of owning an aquarium is regulating the temperature. This is especially important for saltwater and marine applications.

The benefit of getting a thermometer for your tank is that you can determine the exact temperature of the water which will allow you to see if your heater is working properly and to see if the tank is being placed in the correct location.

It can seem overwhelming to pick a thermometer for your tank since there are so many out there to choose from, so I have created a top ten list of the best aquarium thermometers on the market today.


Aquarium Thermometer Reviews

TOOGOO Digital LCD Fish Aquarium Marine Vivarium Thermometer

This thermometer does an extremely good job of regulating the water’s temperature which is going to ultimately give your fish a much better environment to live in. It is very lightweight so it will easily fit in the palm of your hand (it only weighs 3.5 ounces!).

The thermometer is completely submersible in water. The LED screen will allow you to easily read the temperature of the water, even when it is completely submerged. Also, it has a suction base so it can easily sit against any surface in the interior of the tank.

It is versatile since it can be used in numerous applications (freshwater and saltwater). The battery is already included with the thermometer, so you won’t need to buy that separately. Another obvious great thing about this thermometer is its low price.


  • Suction cups allow for easy installation
  • Comes with battery
  • Lightweight and compact


  • Not a lot of features
  • Sometimes it can read slightly off in temperature

KollerCraft TOM Temp Alert Digital Thermometer

This digital thermometer accurately measures your tank water to see if it is too high or too low. This thermometer works in both freshwater and saltwater applications. It comes with a plastic probe, a suction cup, and a 3-foot cord.

It comes with preinstalled preset high and low temperatures. This means that if the water temperature reaches either the low point or the high point, you will be notified that there is an issue with the temperature. You are notified by both an LED light and an audible notification. However, you cannot change the preset temperatures. Also, the sensor warning tends to go off a lot, even at slight changes in temperature.

Since it comes with suction cups, you can easily install it to the tank without any hassle. The time clock is hard to set, but once it is set, there are no issues.


  • Comes with suction cups to easily attach the thermometer to the tank
  • Alerts when temperature is too high or too low
  • Works for both saltwater and freshwater tanks


  • You are not able to change the preset temperatures
  • The sensor is sensitive to any changes in temperature

Zacro LCD Digital Aquarium Thermometer

This thermometer is very compact and lightweight, so it can be easily hidden on or by the tank. You can use it in different tank applications including both freshwater and saltwater. Each thermometer includes the battery that is needed for the thermometer to work properly.

In the thermometer’s settings, you can set it to either Fahrenheit or Celcius depending on what you prefer. Like a lot of other thermometers, it is important to note that the temperature reading can be off by 1 degree or so.

There is a probe that comes with the thermometer that can be completely submerged in the water, but you cannot submerge the actual thermometer. The screen is made from LED lighting, so you can easily read the temperature. Even at night, the temperature can easily be read in the dark because of the light.


  • Comes with required battery
  • The small size allows for it to be easily hidden
  • LED lighting makes it easy to read


  • Temperature reading can be off by a degree or two
  • Can lag or be slow

RISEPRO Aquarium Thermometer

This temperature can effectively read a wide variety of high and low temperatures (-58 to 158 degrees Fahrenheit). It is suitable for many different tank applications including freshwater, saltwater, and marine water. You can easily switch between Fahrenheit and Celcius settings.

A great thing about getting this thermometer is that is super easy and simple to set up – it only takes minutes! It comes with a display unit that can easily be installed over the tank. Then, all you have to do is connect the probe and then place the probe in the water to start detecting the temperature. It’s as simple as that.

You receive two thermometers with this package unlike a lot of other thermometers. Also, you can attach this thermometer with the included suction cups.


  • Easy installation process
  • Detects a wide variety of temperatures
  • Comes with suction cups to easily attach the thermometers


  • No alarm to let you know the temperature is at a dangerous level
  • Frequently needs battery changes

Marina Floating Thermometer

This thermometer is unique compared to the others because instead of being attached with a suction cup or a display, this one actually floats in the water. However, it also comes with suction cups in case you want to secure it to one side of the tank. Because of the design, it is completely submersible.

It includes a safety zone indicator so you know when the temperature is at a dangerous level. However, there is no alert system like a light or an audible alarm. It works for both freshwater and saltwater aquariums.

Because it is being completely submerged in the water, it can be quite difficult to read because the water distorts the thermometer’s image. However, a great thing about this thermometer is that it doesn’t require any batteries and therefore, no battery changes.


  • No batteries
  • Completely submersible in water
  • Includes safety zone indicator


  • No alert or alarm system
  • Difficult to read

American Thermal Horizontal Aquarium Thermometer

This thermometer is very easy to read and it is accurate in its readings. It is installed horizontally on the exterior of the tank. Unlike other tanks that use suction cups to attach the thermometer, this thermometer uses an adhesive. One thing to keep in mind is that over time the adhesive can lose its strength.

A great thing about this thermometer is that it isn’t tailored to one specific tank. It will work with all tanks no matter the shape, size, or application. Therefore, you can use this for both freshwater and saltwater tanks.

Since this is a very basic thermometer, you don’t get a lot of extra features. For example, there is no alert system in place to notify you when the water is too high or too low.


  • Very accurate temperature reading
  • Temperature is easy to read
  • Works for both freshwater and saltwater aquariums


  • No extra features like an alert system
  • Adhesive can lose its strength over time

JW Pet Company Smarttemp Thermometer

This is a very basic thermometer that simply does one job: reading the temperature. This also means there is no alert system which could be a priority for some people. However, it does come with a green safe zone which allows you to easily see the optimal temperature that the water should be at. The numbers on this thermometer are very large, so it is easy to read the temperature.

This thermometer is actually secured with a magnet. This allows for an extremely secure installation, so you won’t have to worry about the thermometer falling off. You can put it anywhere in the tank that you wish. It is completely submersible in water.

Because it reads the temperature by being submerged in the water, there are no extra cords or any extra features to be worried about. That is a big plus for people who are aiming for a more simple or discreet thermometer.


  • Simple and discreet
  • Attached with a magnet
  • Easy to read because of the numbers being large


  • No alert system
  • Temperature readings can be off over time

SUKRAGRAHA Traditional Stick-on Digital Temperature Thermometer

This thermometer is different than the others because it is actually a stick-on thermometer. All you have to do is peel off the adhesive backing and stick it to the exterior of the tank. It reads the temperature of the water through the glass. Also, you don’t need to worry about the adhesive losing its strength because it comes with 10 pieces in the package.

Since it isn’t a digital thermometer, there is no LED light so it will be difficult to read at night. Also, there is no alert system to notify you when the temperature is too high or too low.

The simple design of this thermometer makes for an extremely simple and easy installation process. It also means it’s going to be very discreet in the tank and not too much to maintain.


  • Comes with ten pieces
  • Sticker design is easy to use
  • Easy to install


  • No LED lighting system
  • No alert system

Pet Magasin Digital Thermometer

This is a digital thermometer that has a very big and readable design. Therefore, it will be easy to read through the walls of the aquarium. It works for Fahrenheit and Celcius settings depending on your preference and it can be easily changed.

It works through a battery which is included in the package, so you won’t need to buy that separately. However, it does seem to require frequent battery changes, so you’ll need to keep buying more battery replacements.

This thermometer measures both temperature and humidity levels which notify you of the dampness in the air. Both of these readers are compacted into this one small device. It comes with a specialized gum adhesive to attach it to the wall of the aquarium. The adhesive does not leave any residue on the tank.


  • Measures both temperature and humidity levels
  • Works for both freshwater and saltwater applications
  • It can be easily read


  • Frequent battery changes
  • Cannot submerge in water

Lifegard Aquatics Digital Temp Alert

This is a digital thermometer that includes a large screen that is easy to read. The screen is much bigger than other thermometers with it being 4 inches by 4 inches. However, because there are no LED lights in the screen, it can be hard to read at night.

Also, unlike other thermometers, this one can actually measure room temperature as well. It comes with a long-lasting battery that can be replaced less frequently than other battery-powered thermometers.

It is attached by suction cups which is a secure and reliable way to attach the thermometer. It comes with an alert system that will notify you when the water is either too high or too low. The alert system is easily programmable to the preset temperatures in which you would like to be notified.


  • Durable suction cups included
  • Super large and easy-to-read screen
  • Also measures room temperature


  • Hard to read at night
  • Can be off by degrees more and more over time

Types of Aquarium Thermometers

If you are currently looking for a good thermometer for your aquarium, it is crucial that factor in all of the different things that are going to impact your decision. This is going to ensure that you choose the best aquarium thermometer that matches your wants and needs.

  • Digital aquarium thermometer: A digital aquarium thermometer is set up on the side of the tank with a connecting probe. The probe is the device the reads the temperature. The temperature is displayed on the screen which is what makes this digital. This thermometer generally provides the most accurate results. Also, some digital thermometers come with an alert system so you know when the water has reached a dangerous temperature. For this reason, this is the option most fish tank owners go with.
  • Floating aquarium thermometer: A floating aquarium thermometer is completely submerged in the water and floats at the top while standing up vertically. Some float freely in the water while others are connected to the side with suction cups. Since it looks like a traditional thermometer, it may be a little difficult to read through the water. Some floating thermometers have colors on the thermometer to notify you if the water is at a dangerous temperature.
  • Stick-on aquarium thermometer: A stick-on aquarium thermometer sticks to the exterior surface of the aquarium. A benefit of this kind of thermometer is that they come in big packs, so you won’t need to replace them too frequently. Also, they are easy to read. However, since it is placed on the exterior of the tank, the temperature can be easily influenced by factors such as the room temperature, a heater, direct sunlight, etc. Therefore, this temperature reading is the least dependable.

What to Look for When Choosing an Aquarium Thermometer

  • Temperature accuracy: The main reason fish owners get a thermometer for their aquarium is to get an accurate reading of the water’s temperature. Accurate readings are obviously the exact temperature, but it is usually fine if it is off by 1 or 2 degrees. However, if it is off by any more than that, the temperature accuracy is not good.
  • Easy to use: Thermometers are simple features that enhance the performance of your tank. Therefore, they shouldn’t need to be difficult to use. Floating and stick-on thermometers are generally very easy to use since you just apply it accordingly and let it do its job. A digital thermometer might have a few extra steps, but if it is super difficult to use or install, it probably is not an efficient product.
  • Durable and long-lasting: Thermometers should be durable and long-lasting, so you should not have to replace it in a short period of time. Digital and floating thermometers pass this test. However, stick-on thermometers often have to replaced frequently depending on the pack they come in. This really just depends on how you prioritize how frequently the thermometer needs to be replaced.
  • Easy to read temperature: You can’t get an accurate reading if you can’t actually read the temperature. Digital and stick-on thermometers are typically pretty easy to read. Floating thermometers can be difficult to read since they need to be read through the water. If your water tends to look cloudy or it is not super clear, a floating thermometer could possibly be an issue.
  • Alert system: Some aquarium thermometers come equipped with an alert system. This is put in place to notify you when the temperature has reached an alarming level. This is essential for aquatic life who are extremely sensitive to temperature. Some digital and floating thermometers have this feature, while stick-on thermometers do not.

Purpose of an Aquarium Thermometer

In order for your aquatic life to maintain a healthy lifestyle, their tank’s water needs to be at a proper temperature. This temperature varies depending on the different species of fish you have. It also varies depending on if your tank is freshwater or saltwater. This is where an aquarium thermometer comes in.

An aquarium thermometer allows you to read the temperature of your tank accurately. This will allow you to change the temperature of the water if it is at an alarming level. Most digital thermometers come with some type of alert system that notifies you when it is at a dangerous temperature. This is especially important for species of fish that are very sensitive to different temperatures.

FAQ’s for Aquarium Thermometers

Do I need an aquarium thermometer if my heater says the temperature?

Yes. Aquarium heaters are almost never accurate which could be dangerous. If you want to read the temperature accurately, which you should, you will need to purchase an aquarium thermometer.

Does it work for both Farenheit and Celcius?

Most aquarium thermometers are capable of reading the temperature in both Fahrenheit and Celsius. But it is important to make sure to verify this before buying.

Are aquarium thermometers safe for aquatic life?

Yes. Aquarium thermometers are designed specifically to be safe for aquatic life. This shouldn’t be a worry in looking for a good aquarium thermometer unless the thermometer is not designed specifically for aquariums.

Should I get a digital thermometer with or without an LED lit screen?

If you are going with a digital thermometer, an LED light is a great feature. This will allow you to easily read the temperature even in dim lighting.

Are aquarium thermometers absolutely necessary?

Kind of. Even though they are not absolutely necessary, they are an essential factor in maintaining a healthy tank environment. Making sure your tank is at the proper temperature is going to make sure your fish are living a happy and healthy life. It can even lengthen your fish’s lifespan. This is especially relevant with aquatic life who are extremely sensitive to temperature.

Buying a thermometer for your tank is very important if you want your fish to have a happy and healthy living environment. It is crucial to know if the heater is working and if your tank is in the correct location.

Hopefully, this list educated you of the qualities in a thermometer you need to look out for and show you all of the different thermometers that are on the market.

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