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When it comes to the care of aquarium life, it is important to keep the water at the correct temperature for the types of fish that will be living in it.

In addition to a heater, you will need a good thermometer so you can always know that the water is at the right temperature. The thermometer you choose needs to be as accurate as possible, and operate with a wide range of degrees.

We are going to take a look at five of the best aquarium thermometers, and give you the lowdown on each one, including the pros and cons about each so you get the complete picture.

Our Picks

1. Most Accurate Reading – Zacro LCD Digital Aquarium Thermometer

 The Zacro pack comes with two LCD digital aquarium thermometers and costs around $10. It is easy to apply with the suction cup, and just as easy to use. The probe is the only part that should be submerged. The rest of the thermometer should stay above the water level.

2. Best Ease of Use – LCR Hallcrest A-1005

The LCR Hallcrest A-1005 is one of the easiest aquarium thermometers to use, and it only costs around $5. It is easy to read, and mounting it to the side of the aquarium is simple. It can be easily moved around even after it is mounted, and it will stay in place.

3. Best for Bettas – SunGrow Digital Betta Thermometer

Bettas need particular care, which includes having their water at an optimal temperature (78°F to 80°F) even when there are changes in room temperature. The SunGrow Digital Betta Thermometer will help to ensure that the water temperature in your tank is in the proper range for bettas.

4. Best for Saltwater Tanks – AODE Digital LCD Aquarium Thermometer

The AODE Digital LCD aquarium thermometer is great for freshwater and saltwater aquariums and has a wide temperature range (-50°C to +70°C). It also has an operating temperature range of -10°C to +50°C. It is powered by a single battery, which is included.

5. Best Dual Temperature Readings – Zoo Med Digital Aquarium Thermometer

The Zoo Med Digital Aquarium Thermometer is made for tanks of all sizes, and it is easy to use. This thermometer as a temperature range of approximately 10°F to 140° F, and is ideal for keeping the temperature in your tank regulated.

Best Aquarium Thermometer Reviews

The purpose of this article is to help you choose the best aquarium thermometer for your needs. We are going to review five different thermometers that can be used for a variety of aquatic life, including one that is specifically for bettas.

1. Zacro LCD Digital Aquarium Thermometer

Zacro LCD Digital Aquarium Thermometer Fish Tank Water Terrarium Temperature

Get The Zacro LCD Digital Aquarium Thermometer

The Zacro aquarium thermometer comes in a package of two and is easy to apply and use. It has a wide temperature range, from -50°C to +70°C, and an operating temperature range of -10°C to +50°C. The LCD display is large and easy to read, but the design is compact.

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  • Powered by one LR44 battery
  • Readings to within 0.1 degree
  • Wide temperature range


  • Problems with functionality
  • No two pairs read the same temperature


If you are looking for an aquarium thermometer that is easy to use and read, and that is extremely accurate, the thermometers from Zacro are a good choice. They are battery operated (the battery is included for both thermometers). This and other Zacro products come with a 24-month manufacturer’s warranty.

2. LCR Hallcrest A-1005

LCR Hallcrest A-1005 Liquid Crystal Vertical Aquarium Thermometer

Get The LCR Hallcrest Thermometer

Do you want a thermometer that you don’t have to submerge into the water? The LCR Hallcrest A-1005 just sticks to the side of the tank, and it is easy to take off and move around to other areas on the outside of the tank. It is easy to read, and you will always know the temperature of the water, and be able to adjust it when necessary.


  • Easy to read
  • Vertically mounts to the outside of any aquarium
  • Can easily be moved


  • Some reports of inaccurate readings
  • Some reports that it stops working within a few months
  • Doesn’t stick to the side of the tank as well as manufacturer claims


As you can see, the LCR Hallcrest A-1005 has its good and bad points. But, for the price, you really can’t go wrong. It will do the job that it is intended to do, and it is easy to use. It is not submersible and sticks to the outside of your tank.

3. SunGrow Digital Betta Thermometer

SunGrow LCD Digital Betta Thermometer, Black, Accurately Reads Tank Water Temperature, Maintains Betta's Real Habitat, Easy to Install, Comes with 2 Suction Cups and Battery, 1-Pack

Get The SunGrow Digital Betta Thermometer

Like goldfish, bettas require cooler water temperatures. If their water gets too warm, they can end up lethargic. Using the SunGrow Digital Betta Thermometer will ensure that the water temperature in your tank will stay at the optimal range for bettas. It is made of lightweight plastic, yet it is durable, and it is easy to use.


  • The screen reader is visible and easy to read
  • Resilient to room temperature changes
  • Better accuracy than floating thermometers


  • Reports of residue on the unit
  • Reports of broken units
  • Reports of inaccurate readings


All in all, if you are looking for an inexpensive thermometer for your betta tank that is an alternative to a floating aquarium thermometer, the SunGrow Digital Betta Thermometer is a decent choice. It does have its issues, but for the most part, users seem to be happy with its performance.

4. AODE Digital LCD Aquarium Thermometer

The AODE Digital LCD aquarium thermometer has a large LCD display that is easy to read. This unit is simple to install and use, and it will ensure that you are always aware of any temperature changes in your aquarium. The design is compact, so it isn’t going to stand out and ruin the appearance of your tank.


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  • The probe can be submerged directly into the tank (do not submerge thermometer)
  • Powered by a single LR44 lithium battery (included)
  • Wide temperature range


  • Reports of inaccurate readings
  • Can become more inaccurate over time
  • Stays on all the time and battery dies too quickly


While there are some complaints about this aquarium thermometer, for the most part, it does its intended job, and it is easy to use. Most users find that it is relatively accurate, and it can be used in both saltwater and freshwater aquariums.

5. Zoo Med Digital Aquarium Thermometer

Zoo Med Digital Terrarium Thermometer, 3 x 2 x 1&quot

Get The Zoo Med Digital Aquarium Thermometer

There are many aquarium thermometers that cannot be submerged in water. The Zoo Med digital aquarium thermometer is different. The external sensor can be submerged, and it is still going to give you an accurate reading so you always know the temperature of the water in your tank.


  • External sensor can be submerged
  • Measures temperatures in Fahrenheit and Celsius
  • Easy-to-use LCD readout


  • Temperature readings are sometimes off
  • Some units die after a few months
  • Some units have arrived with no battery


Not all aquarium thermometers can be submerged, and not all of them give readings in both Fahrenheit and Celsius. The Zoo Med digital aquarium can and does, and it seems to be very popular with aquarium owners. There are some reports of defects, but most reviews are positive.

Final Thoughts

No matter what type of aquarium you have, fresh or saltwater, you need to keep it at a constant and optimal temperature for the aquatic life inside.

Having a heater and a thermostat isn’t enough. You also need a good thermometer, and one of our top recommendations is the Zacro LCD Digital Aquarium Thermometer.

You might have seen varying temperatures when using the strips or floating thermometers but the Zacro can give you accurate temperatures and are easy to read.