The Best Aquarium Thermometer of 2021 – [Reviews & Buyer Guide]

Best Aquarium Thermometer

Take The Guesswork Out of The Equation – Get The Best Aquarium Thermometer

Monitoring the water temperature of your aquarium is the most important thing you can do to ensure the health and safety of your fish. Neglecting this simple step might put your fish’s life in jeopardy. Some species of fish are extremely sensitive to subtle temperature changes, and simply guessing by feeling the water with your hands doesn’t yield accurate results. Getting the best aquarium thermometer you can afford is the way to go if you want to enjoy your home aquarium and keep your fish active healthy:

1 – Zacro LCD Digital Aquarium Thermometer

[Editor Choice] Zacro Digital Aquarium Thermometer Fish Tank Water Terrarium Temperature


The Zacro LCD Digital aquarium thermometer is a light and compact device that is very practical and easy to use.  It comes with a probe and a set of LR44 batteries.

It has an impressive range that stretches from -50 degrees Celsius to +70 degrees Celsius. The results are displayed on a good quality large LCD that allows for easy reading. The temperature measured by the Zacro is highly accurate and with a level of resolution that is correct to within 0.1 degrees.

The recommended method of usage is to submerge the probe into the fish tank while keeping the thermometer outside by attaching the suction cups to the side of the tank or any nearby smooth surface. The probe is also equipped with a suction cup that can be attached inside the tank.  To preserve the battery life, the power button should be pressed for 3 seconds in order to turn off the device.

The manufacturer guarantees 100% customer satisfaction and offers a 2 year warranty with the purchase of this device.

2 – HDE Digital Aquarium Thermometer


 HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control

The HDE Digital aquarium thermometer is a highly convenient unit that provides accurate results and is easy to set up. The package includes the sensor, the display unit, and the battery.

It boasts an operating range that goes as low as -10 degrees Celsius and reaches a maximum of 50 degrees Celsius. The display screen is remarkably large and enables you to read the results without any strain. The temperature given by the HDE is correct to within 0.1 degrees.

To measure the temperature of your fish tank, the suction cups of the sensor should be attached inside, either low or high depending on where you want them, while the suction cups of the display are fixed to the side of the tank.

Even though the display screen is water resistant, it should be kept outside of the tank as it won’t be able to show the result if it is fully submerged. The manufacturer recommends shutting off the device after usage in order to save the battery life.

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

[Top Rated]


The LCR Hallcrest A-1005 is a 5 ¼ inches by ¾ inches liquid crystal thermometer that is extremely easy to read and yields accurate results. It is one of the cheapest units we’re reviewing in this list.

The device is installed vertically on the outside of your fish tank. It has a colorful exquisite design that gives your tank an added touch of color. It lights up very well and the result is displayed in very large numbers that can be read with no struggle.

This Thermometer registers temperatures with a very good resolution of 0.1 degrees. While this unit is better suited for Betta plastic tanks, it sticks quite easily on the glass of any fish tank. And since it is placed outside, you won’t have to worry about algae sticking on your device or damaging it.

4 – RISEPRO 2 pack Digital Water Thermometer

 RISEPRO Aquarium Thermometer, 2 pack Digital Water Thermometer For Fish Tank Aquarium Marine Temperature Vivarium Reptile Terrarium

The RISEPRO 2 is a highly versatile thermometer that comes in a stacked package containing 2 aquarium thermometers, a set of 4 AG13 button powered cell batteries, and detailed instructions.

It has a fairly a wide range that reaches as low as -50 degrees Celsius, and upwards of 70 degrees Celsius. The measuring accuracy of the device is at +/- 1 degrees and the resolution is within 0.1 degrees. The LCD display is amply large and the numbers appear very clearly.

To use the Thermometer, the suction cups of the display unit are clamped against the tank glass while the sensor probe is submerged in the water and attached from the inside with its own suction cup. It is equipped with a feature that allows you to rapidly switch between Celsius and Fahrenheit. The device must be turned off after usage in order to preserve the battery life.

A strong selling point for the RISEPRO is the fact that it is suited for different types of water.  It is also adept at monitoring the appropriate temperature for reptiles, a high maintenance task that most thermometers aren’t equipped to handle.

  5 – JW Pet Company Smarttemp Thermometer Aquarium Accessory

[Best Value]

 JW Pet Company Smarttemp Thermometer Aquarium Accessory

The JW Pet Company Smarttemp is a cheap aquarium thermometer that has a classic design. It offers great value for the price thanks to several practical features.

This device has a high-end accuracy of -/+ 1.5 degrees Celsius and provides results in both Fahrenheit and Celsius. It is designed with a green safe zone that is supposed to indicate the optimal temperature range. The numbers displayed are sufficiently large enough that they can be read with no strain or effort.

The use of the Smart temp incorporates a thermometer and a magnet.  The former is placed inside the tank while the latter is placed outside with the task of holding the thermometer in place. The process requires no suction cups.

An issue worth noting with this device is the quality of the thermometer glass. It doesn’t feel very sturdy and looks liable to break inside the tank after extended usage.

6 – Fluval Wireless 2in1 Digital Thermometer

 Fluval Wireless 2in1 Digital Thermometer

The Fluval Wireless is a compact and stylishly designed thermometer that is set up to simultaneously measure, and display, the temperature of the tank and the room. It is suited for both freshwater and saltwater aquariums.

It has a large LCD display that is easy to read. It is advertised as being able to measure room temperature with accuracy within 10 degrees Celsius. Its use is simple and intuitive and involves no probes or wires; you simply mount the device on the fish tank glass and wait for the room and tank temperatures to be displayed.

While this thermometer does a satisfactory job at measuring water temperature, the same can’t be said about the result we got for the room. Since this feature is a strong selling point for this unit, it would be hard to justify the price if it doesn’t work properly.

7 – American Thermal Instruments Aquarium Thermometer


 American Thermal Liquid Crystal Aquarium Thermometer Horizontal


This Thermometer from American Thermal Instruments is another liquid crystal unit that is mounted horizontally outside the aquarium. It is made out of flexible plastic and is quite compact, measuring 4-5 inches long by .5 inches high.  It has an eye catching design and its temperature measuring is fairly accurate.

The method of usage is quite convenient and straightforward. You simply place the thermometer on the aquarium glass and wait for color changing liquid crystal to provide the temperature. It is easily removable, allowing you to switch between aquariums with complete ease.  The device is better suited for flat/non-curved surface and could struggle to remain mounted on a surface with a substantial curve such as the one in a round shape aquarium.

If there is one complaint you could make about this product, it’s the cheap low-grade plastic it is made of.

8 – AODE® Digital LCD Aquarium Thermometer

This Thermometer from AODE comes at a cheap price while possessing a lot of the attributes of the higher end models. It is equipped with a long 90cm cable that makes it suitable for large fish tanks.

It has a temperature range of -50 degrees to +70 degrees Celsius and an operating temperature from -10 to +50 degrees Celsius. It measures temperatures with an accuracy of +/- 1°c and a resolution to within 0.1 degrees. The LCD display is large and makes reading the numbers an easy process.

When using the AODE, it is imperative to make sure that only the probe is submerged. The display isn’t water resistant and could be irreparably damaged if precaution is not taken. To maintain the battery, the unit should be turned off when it is not in use by holding the power button for 3 seconds.

9 – CoZroom LCD Digital Aquarium Thermometer (3 Pack)


This set of 3 aquarium thermometers offers an unparalleled value for the price. The CoZroom LCD digital is a compact and sturdy device made from top grade plastic. It is easy to use and is powered by a two button battery.

The temperature range of the thermometer is substantially wide and goes down to temperatures as low as -50 degrees Celsius and reaches a maximum of up to +70 degrees Celsius. The operating temperature ranges from -10 degrees to +50. Thanks to its high accuracy of 0.1 degrees, the device allows you to adjust the water to the specific temperature that suits your fish.

The device works in the same fashion as the similarly built thermometers that feature a censor and a display. The display unit is mounted on the glass of the tank using the suction cup, and the censor probe is submerged inside the tank and fixed either low or high to the side. The result displayed is easy to read thanks to the large top grade LCD.

The manufacturer warns against submerging the thermometer in water and recommends shutting off the device to preserve the battery life.

How To Choose The Best Aquarium Thermometer?

Aquarium thermometers are fairly minimalist and simple devices, so being able to decipher their characteristics and distinguish the good from the mediocre doesn’t require any technical know how. But just to stay on the side of caution, it wouldn’t hurt to have some rudimentary understanding of the essential features that you’d expect to find in the best aquarium thermometer


The simple the design of the device is, the easier it is to use, and the less likely it is to malfunction.

Temperature range

It indicates the lowest and highest temperature extremities that the thermometer can reach. A good device should at least be able to go as low as 10 degrees Celsius, and as high as 40 degrees Celsius.


A thermometer should be able to provide temperatures with a minimum level of accuracy to within 0.1 degrees. For example, 26.24 degrees Celsius has greater resolution than 26.2.


A good quality battery will last for a long time and will save you the hassle of having to change it every month.

Quality of the display

Your thermometer should be equipped with a large LCD display that allows for easy reading. The same should apply to non-electronic devices.

If you cover all the bases detailed above, there isn’t much you can get wrong when you’re trying to purchase an aquarium thermometer. One thing to watch out for is the plethora of cheap knock offs that you’ll come across on the internet; they should be avoided at all costs. It is advisable to only make your purchase from trusted sites like Amazon.

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[1] how to set up an aquarium thermometer

[2] Are Aquarium thermometers important?

[3] how to maintain ideal temperature

[4] general definition

Updated: — 4:32 am