Best Aquarium Thermometers: Top 15 for 2022 (Reviews & Guide)

By: Mary
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Tons of gadgets promise to help you care for your fish. There are heaters, filters, oxygenators, and even LED lights. But which of these do you actually need? It helps to think about what’s best for your fishes, and what’s just decorative in function. The best aquarium thermometers, for example, help you keep an eye on the water temperature. If you own tropical fish, this is extremely important because the temperature can be the difference between life and death for your fishes. Another question you might ask yourself is: How do I choose the right thermometer? This guide helps you answer that question.

The Guide to Choosing Aquarium Thermometers

Without wasting your time, here are four things you should look out for when buying aquarium thermometers.


For many fish lovers, the visual appeal is, perhaps, one of the most important reasons why they buy aquariums. But, a thermometer can threaten, and even undo, all that beauty. That’s why it’s important to get an appealing one. Luckily, there are many LCD thermometers with sleek and modern designs.


Thermometers are some of the least expensive aquarium accessories you could get; most of them cost less than $10. However, there are products that cost much more, and are worth every penny. If you can afford one, it’s always best to look for a blend of value and price.


Aquarium thermometers work in primarily one of two ways: by probe or back plate. Those with probes also have wires that reach into the aquarium and measure the temperature of the water. The back plate design requires the thermometer itself to be in contact with either the glass or the water. It basically comes down to which one you prefer.


When installing the thermometers, you can either stick them onto the aquarium, hang them on the side, or use a suction cup, depending on the kind of device you buy. Some users complain that suction cups leave a mark on the side of their aquariums. But if your aquarium is made of high-grade acrylic, you may not have this problem.

Top 15 Best Aquarium Thermometers Money Can Buy

Now, let’s go over some of the best thermometers we could find. Remember to keep the tips we just discussed in mind as you browse through these products.

Digital Touch Screen Aquarium Thermometer with LCD

Sometimes, we judge a design by how seamless and easy it is to use. By that standard, the Digital Touch Screen Thermometer is a fantastic product. It is a single rectangular device with a 3.2” LCD display and an accuracy of up to 0.1 degrees.

Furthermore, the thermometer works from outside the fish tank. You attach it to the tank and the sensitive back plate reads the temperature of the water. You get the readings on the large, easy-to-interpret display, and you can see it from anywhere in the room. Because it’s not submersible, this product is suitable for both fresh and saltwater aquariums.

Zacro LCD Digital Aquarium Thermometer

Unlike the previous product, this thermometer’s probe needs to go into the water to function. However, the submersible nature is actually what makes it such a good product. It also has an LCD display that indicates the temperature of the water, and can be set to either degrees or Fahrenheit.

You should never insert the device, only the probe. The Zacro LCD thermometer is accurate to 1 degree and has a temperature range of between -50 degrees Celsius and + 70 degrees Celsius. The thermometer also comes with a long lasting LR44 battery.

Qguai Aquarium Thermometer, C/F Switch LCD Digital Fish tank

The Qguai Aquarium Thermometer is another high-tech device and it works using the same principles as the other ones we’ve considered. You attach the product to the outside of the aquarium and it reads the water’s temperature through the glass.

The sensitivity has been adjusted by the manufacturer to correct for any inefficiencies caused by the glass. This thermometer is also very functional and can be used for various aquariums, including fresh water, salt water, and marine water. It can also be used in reptile habitats. There’s a 6-month warranty on the product.

Marina Floating Thermometer With Suction Cup

Some users prefer an analog thermometer to a digital one. With these old-fashioned instruments, you can measure the temperature much more accurately, and it’s so small that you can hide it behind some aquatic plants. The Marina Floating Thermometer has a suction cup that safely attaches it to the inside of the tank.

The thermometer also has a safe zone that alerts you when the water is too hot for your aquatic pets. However, you should be careful when using this product because some users have complained of the suction cup leaving a permanent mark on the inside of the aquarium. If your tank is made of acrylic, you may want to avoid this thermometer.

RISERPO LCD Digital Aquarium Thermometer

The RISERPO thermometer is a great bargain, offering you decent value at a very affordable price. Many people think affordable always means cheap, but that’s not the case here. This thermometer has a simple operating principle – a submersible probe that measures the water’s temperature and an LCD display that shows you everything you need to know.

The device is accurate to 1 degree and it comes with a long-lasting built-in battery. You can also use it to measure the temperature in a reptilian habitat.

JW Pet Company Smarttemp Thermometer Aquarium Accessory

The problem with many internal aquarium thermometers is that they leave an indelible mark on the aquarium, ruining its beauty. With the JW Pet Company Thermometer, you’ll have all the benefits but none of the disadvantages of the internal thermometer. The product is held in place by a magnet on the outside of the tank.

Besides that, it also has large and easy to read numbers, and a green “safe zone” indicator for your fish’s benefit. The thermometer is accurate to about 1.5 degrees Fahrenheit. With a weight of just 0.9 ounces, you’ll barely even notice it’s in the aquarium.

Fluval Edge Digital Aquarium Thermometer

So far we’ve seen digital thermometers with probes and sensitive back plates. We’ve also seen submersible analog thermometers with suction cups and magnetic fixators. The Fluval Edge Thermometer, however, is a sophisticated blend of the two, being an analog thermometer with a sensitive back plate.

Fluval as a manufacturer is very experienced in designing products for aquariums, and they pull on their wealth of experience in this product. It has a scale with large numbers that’s easy to read, and a range of between 64 and 86 degrees Fahrenheit. The thermometer is also very affordable.

VIVOSUN 2-Pack LCD Digital Aquarium Thermometer

Have you ever worried about the length of a digital thermometer’s probe? If you have a large tank, you’ll want a probe with wire long enough to reach deep into the tank. The VIVOSUN thermometer has a cable of 40 inches long so that’s not going to be a problem.

The thermometer also has two suction cups – one for attaching the cable on the inside of the tank, and the other for attaching the thermometer on the outside. You can calibrate the product to display in Celsius or Fahrenheit, and can expect a figure accurate to 1 degree Celsius. Since this thermometer has not one but two suction cups, it may leave marks on your aquarium.

Lomodo 4 Pack Floating Thermometer Aquarium Glass

If you’re not a fan of suction cups, you’ll be glad to know that this thermometer can function just as well by floating around in your fish tank. You can even think of it as another decorative piece. The device has ball bearings on the bottom that give it balance, as well as a highly sensitive mercury reading.

It is suitable for use in large or small tanks, as well as indoors or outdoors. This product comes in a pack of four, useful for you if you have multiple aquariums or want to gift some to a friend.

Aquarium Digital Waterproof Thermometer LCD

Most owners are afraid of submerging their digital thermometers for fear of water damage. Here we have a product that is designed to be submerged. It has waterproofed edges and a suction cup for attachment to the inside of the tank. Once you locate the most comfortable spot for you, you’re good to go!

The thermometer also has the safe zone for most tropical fish written below the LCD indicator. That way, you know when it’s time to act. Considering the product is just as affordable as other digital thermometers, we’d say it offers great value for money.

Marina Stainless Steel Thermometer

The Marina Thermometer combines the durability of a stainless steel composition with the ease-of-application that comes with a simple hook design. You can attach the product to your aquarium by simply hanging it on the side; no suction stains, no permanent damage.

The thermometer is 4.5 inches long and it has a remarkably accurate reading. And with a safe-zone highlight, you can easily tell when your fishes are in safe waters! Marina Stainless Steel is alcohol-based, and unlike mercury-in-glass thermometers, it is perfectly safe for fishes.

DaToo Aquarium Thermometer

At the end of the day, simplicity always wins. That’s why the DaToo Aquarium thermometer still a fantastic choice for fish-lovers. The device itself has a waterproof plastic container with a powerful suction cup underneath.

The device also features a sensitive back plate that can measure the water’s temperature accurate to 1 degree. You don’t need any additional installation or instructions. You simply stick the device on the inside of the tank and begin tracking the water’s temperature.

Inkbird Wireless Thermometer and Hygrometer

Manufactured using some of the most advanced temperature-measuring technology you’ll ever come across, the Inkbird Wireless Thermometer is for a different breed of aquarium owners. The device pairs with an app, available on Google Play Store and iOS, where it feeds all the aquarium data.

You can review the current water temperature as well as a chart of the temperature changes over time. The device itself is a small, barely noticeable, disk that can be attached to the aquarium wall via a suction cup. It has a probe for measuring the water temperature, and an overall waterproof design. It costs up to ten times as much as some thermometers on this list, but it is worth it.

JJMG Fish Tank Thermometer

This Thermometer has a minimalist design that could make it almost blend with the aquarium, depending on the tank’s design. The product goes on the outside of the aquarium, and it measures the temperature using a highly sensitive plate.

The JJMG Thermometer is great for any kind of pet habitat because it stays on the outside. One of the problems you might have with this product is that it doesn’t display the temperature in Celsius, only Fahrenheit.

Fluval Wireless 2 in 1 Digital Thermometer

Fluval Wireless thermometer performs two equally important functions. It measures the temperature of the fishes and the owner’s habitat! It has two LCD displays, one for the aquarium and the other for the room the aquarium is in.

The readings you get from the Fluval Wireless Thermometer are accurate to 10 degrees Celsius. The device is great for both salt and freshwater aquariums, although it might not work as well for reptilian habitats.

Our Final Thoughts on Aquarium Thermometers

Most aquariums have an indicator of the safe zone for your fishes. Outside of temperature, the fish could die. Therefore, it falls on you to keep the water within the optimal range. An aquarium heater is best for this purpose, and once you find an equilibrium between the heater and the thermometer, you’ll have little to worry about. Additionally, when using the best aquarium thermometers, it’s important to make sure they are working correctly. You can do this by testing them regularly using water of varying temperatures in a glass. If the thermometer can’t detect the changes in temperature, it may be time to replace it.