Best Aquarium Thermometers (Reviewed 2021)

Updated on January 30, 2021 by

This post includes affiliate links, for which we may earn a commission at no extra cost to you should you make a purchase using our links.
As an Amazon Associate, we earn from qualifying purchases. Learn more.

Do I need a thermometer for my aquarium?

Setting up the ideal aquarium home for our fish can sometimes be a hassle and a bit frustrating too if all the necessary accessories are not in place. The right water conditions including its temperature are essential for the well-being of the aquarium inhabitants, including fish, plants, or corals.

Temperature is the degree of coldness or hotness of a body or medium, and this includes, of course, the aquarium water. Housing an aquarium species in an environment with unsuitable temperature can be detrimental to its comfort and even worse, the life of the species.

This degree at which the water is hot or cold can be precisely determined using the best aquarium thermometer.

Some thermometers would give you a clear digital display of the reading in ˚C or ˚F alone, while some are built to display the reading in both, giving you the possibility to choose your preference.

The fish tank thermometers are calibrated to give you the reading (analog or digital display) of the exact temperature of the body. An aquarium thermometer is therefore used to determine whether the water temperature of the aquarium tank is suitable for the species it houses.

There are three main types of aquarium thermometers which include, digital, liquid-filled and adhesive thermometers.

The digital aquarium thermometers usually come with a probe that is inserted inside the water while the display unit stays outside, though there are some exceptions.

The liquid-filled thermometers are usually like the old-fashioned mercury bulb thermometers which come with a sensitive fluid that rises and falls to give precise temperature readings. They usually sit inside the tank, either floating or sinking to give accurate temperature reading. Some could come with a suction cup too.

The adhesive aquarium thermometers are usually thin and flexible thermometer strips which are affixed on the outside of the aquarium to give a relatively accurate reading.

This article covers a review of different, affordable and easily accessible aquarium thermometers to suit different preferences.

Best aquarium thermometers compared

Our Top Pick
Zacro LCD Digital Aquarium Thermometer
Zacro LCD Digital Aquarium Thermometer
Check On Amazon
Ultimate Accuracy
Neptonion Aquarium Thermometer LCD
Neptonion Aquarium Thermometer LCD
Check On Amazon
High Quality Probe
VIVOSUN LCD Digital Aquarium Thermometer
VIVOSUN LCD Digital Aquarium Thermometer
Check On Amazon
Large Screen
Capetsma Aquarium LCD Thermometer
Capetsma Aquarium LCD Thermometer
Check On Amazon
Magnetic Suction
JW Smarttemp Thermometer
JW Smarttemp Thermometer
Check On Amazon
LCR Hallcrest Liquid Crystal Thermometer
LCR Hallcrest Liquid Crystal Thermometer
Check On Amazon
Multi Purpose
Cooper Atkins Digital Pocket Thermometer
Cooper Atkins Digital Pocket Thermometer
Check On Amazon
Never Fails
Marina Floating Thermometer
Marina Floating Thermometer
Check On Amazon
4 PCS Pack
Jansamn Brewing Thermometer Strip
Jansamn Brewing Thermometer Strip
Check On Amazon
USB Powered
Keynice Digital Thermometer
Keynice Digital Thermometer
Check On Amazon

1. Zacro LCD Digital Aquarium Thermometer

Our Top Pick
Zacro LCD Digital Aquarium Thermometer

Zacro LCD Digital Aquarium Thermometer

The first review on our best aquarium thermometers list is the Zacro LCD Digital Aquarium Thermometer, which is suitable for different water types including freshwater, tap water, saltwater, among many others.

The thermometer is very easy to use, requiring only to insert the probe into the water to get the exact temperature value.

This thermometer has a large LCD screen to give an easy to read display of the temperature reading.

The temperature reading can be displayed in ˚C or ˚F, saving you the stress of manually converting from one to the other and it has a high accuracy of providing readings within one degree.

It has a temperature range of -50˚C to +70˚C and a working range of -10˚C to +50˚C. Moreover, the price is fairly cheap for its high quality and large function.

  • Portable with high functionality
  • Displays reading in ˚C and ˚F
  • Battery-powered
  • Built-in suction cup
  • Large LCD display for an easy read
  • The suction cup stability could use some improvements
  • The battery cover is difficult to remove

2. Neptonion LCD Aquarium Thermometer

Top Quality Probe
Neptonion LCD Aquarium Thermometer

Neptonion LCD Aquarium Thermometer

The Neptonion LCD digital aquarium thermometer is designed for monitoring, regulating, and maintaining the water temperature of the aquarium. It is quite portable with a compact and durable design.

It is designed within two suction cups, which are attached to the LCD and the end of the probe, one serving as a thermostat and the other as a fixed probe.

It is built with a high-quality probe which is fully waterproof, enabling it to work well underwater without corroding.

Battery-powered aquarium thermometer, it has a large LCD screen to give a clear and easy to read display of the temperature reading either in ˚C or ˚F as you choose.

It has a large range of temperature values spanning from -50˚C to 70˚C. This temperature is highly accurate with about +/- 0.1-degree deviation. It is fairly cheap for its high quality and great accuracy.

  • Large LCD display
  • Highly accurate with about +/- 0.1-degree deviation
  • Displays temperature reading either in ˚C and ˚F
  • Fairly cheap for a good quality aquarium thermometer
  • Suction cups can be difficult to adhere to the tank

3. VIVOSUN LCD Digital Aquarium Thermometer

LCD Digital
VIVOSUN Aquarium Thermometer

VIVOSUN Aquarium Thermometer

This is a great aquarium thermometer with a compact and durable design for monitoring and maintaining the water temperature of the fish tank. It is battery powered and comes with a built-in LR44 button battery which is durable and replaceable and can last for a long time.

It has a large LCD screen which displays a clear and easy to read temperature readings.

It gives a highly accurate temperature value which can either be displayed in ˚C or ˚F as chosen, while it’s built with an adjustable unit temperature, which makes it easy to adjust the temperature between ˚C and ˚F just by long-pressing on the power button or sliding the change bar.

It comes with a fully waterproof and high-quality probe that works perfectly well without the risk of corroding or breaking.

It comes with a superior long cable which is connected to the probe to allow for accurate temperature measurement even in very large fish tanks.

It comes with two suction cups, one is used to attach the cable to the tank while the other is attached to the thermometer.

  • High-quality waterproof probe
  • Large LCD display for an easy read
  • Suitable for a large variety of application
  • Highly accurate
  • Battery-powered which can last for a long time
  • Can have display issues
  • Difficulty with suction cups adhering to the tank

4. Capetsma Digital Stick-on Aquarium Thermometer

Digital Touch Screen
Capetsma Aquarium Thermometer

Capetsma Aquarium Thermometer

The Capetsma is a great aquarium thermometer built with a modern appearance and sleek design. Built for wide range functionality, suitable for freshwater and saltwater aquatic environments.

They are also suitable for aquarium terrarium inhabited by amphibians or reptiles.

The thermometer has a touch to set function with a high and low-temperature warning.

It is designed with a large transparent clear screen which displays an easy to read large digital values of the temperature reading. It is battery powered and comes with an extra battery fully inserted in the red battery cover just below the large LCD screen.

It’s cordless and does not have a messy wire nor probe, rather it’s built with a backside temperature sensor that sticks to the outside of the fish tank glass, and gives an accurate temperature reading.

This prevents electronic components from corroding and will avoid water infiltration from the tank. This thermometer is decently accurate with +/-1 degree deviation and can show the temperature reading both in ˚C and ˚F.

  • Large and transparent screen for clear display of digital values
  • Designed with a touchscreen functionality
  • Absence of probe or messy wires
  • Has a touch to set high and low-temperature warnings
  • Relatively accurate within a one-degree deviation
  • No technical instructions included

5. JW Pet Company Aquarium Thermometer

Magnetic Suction Mount
JW Pet Smarttemp Thermometer

JW Pet Smarttemp Thermometer

This is a unique handy and portable aquarium thermometer with a sleek design and excellent functionality. It is only 6 inches long and an inch wide. It is just the right thermometer on the go.

It has an analog display of readings. The temperature numbers and values are shown in black but on a white background which makes it an easy read.

This fish tank thermometer is designed with a magnetic suction and does not require a cup suction. The magnet suction goes on the outside of the aquarium to hold the thermometer firmly in place.

It also allows it to be moved around the tank without for instance opening the aquarium lid and disturbing the fish.

It comes with a green-safe zone which indicates the optimal temperature range for most use and it’s relatively accurate with about +/- 2 degree deviation.

However, due to the fact that this thermometer is made of glass, it is fragile and can easily break. This requires that this thermometer should be treated with great care.

  • Magnetic suction instead of cup suction
  • Designed with a green-safe zone printed on it
  • Very easy to use
  • Clear and easy to read numbers
  • Portable aquarium thermometer
  • Fragile and can easily break
  • Relatively low accuracy

6. LCR Hallcrest Aquarium Thermometer

Stick-on Thermometer
LCR Hallcrest Vertical Aquarium Thermometer

LCR Hallcrest Aquarium Thermometer

This aquarium thermometer is just the right choice for its simplicity. Built with a portable and sleek design and suitable on-the-go, to be easily carried about, and can be easily fitted into the pocket.

This thermometer is stuck to the glass of the tank, as far from the heater as possible to adequately read the temperature of the aquarium tank.

It comes with multiple colors for different indications. The green box indicates the current temperature value, the brown box indicates one degree higher and the blue box indicates one degree lower.

Nonetheless, there could be a mixing of colors depending on the actual temperature of the tank water, usually when the temperature value is in between numbers, but this can be easily figured out if one knows how to accurately read off the values.

However, it has a relatively low accuracy of about +/- 2-degree deviation and it does not glow in the tank nor show numbers when the tank lights are on.

The longevity of this device is in doubt as many users have reported this device not to last for extended periods.

  • Great sticky adhesion
  • It has a clear easy to read display of readings
  • Fairly cheap
  • Portable
  • Difficulty to read off values in the dark
  • Could be off by up to 2 degrees

7. Cooper Atkins Waterproof Tip Digital Thermometer

High Accuracy Thermometer
Cooper Atkins Digital Thermometer

Cooper Atkins Digital Thermometer

The Cooper-Atkins pocket thermometer is a great and accurate choice to measure the aquarium water temperature. It has a genuine OEM (original equipment manufacturer) replacement part.

It is suitable for many aquarium purposes, including freshwater, saltwater, and usual tap water.

It does not have a suction cup to affix it to the tank rather it has a long and waterproof probe that touches the water to give an accurate temperature reading.

The thermometer is designed with a probe that comes in a sleeve. The probe is removed from its sleeve and inserted into the aquarium for temperature measurements and is inserted back into the sleeve after the measurement has been received and recorded.

It is highly accurate having a temperature range of about -40 to 450 ˚F.

However, the temperature reading is only displayed in F and cannot be converted to ˚C. This makes it a hassle to manually converting the temperatures to ˚C.

Also the sleeve wears off quickly which may expose the probe to damage and shorten the longevity of the device.

  • It is quite accurate and easy to read
  • Has a genuine OEM replacement part
  • Quite easy to use and maintain
  • High accuracy
  • Temperature readings only in ˚F
  • Has a large head resulting in difficulty in balance

8. Marina Aquarium Thermometer with Suction Cup

Great Classic Thermometer
Marina Floating Thermometer

Marina Floating Thermometer

This is a great thermometer for aquariums with multiple functionalities. It has a very simple and sleek design while being highly effective at aquatic temperature readings.

The thermometer is designed to float in the water in a vertical position. It also comes with a suction cup which gives an optional installation to be affixed on the aquarium glass.

It is relatively accurate, providing a clear and easy to read temperature analogue reading in both ˚C and ˚F.

It also comes with a green safety zone temperature range indicator for most fish of freshwater and saltwater descent. This is a great function to know when the temperature is right for the aquarium species and this works for many tropical fish.

This thermometer is fairly cheap and pocket-friendly, just the right choice for a low budget device with a price tag that is less than $3.

It does not require a battery to operate, so you don’t need to be worried about replacing batteries.

However, the downside is made of fairly thin glass and is very fragile. This requires you to treat this device with utmost care.

  • Provides accurate, clear, and easy to read values
  • Comes with a green safety zone indicator for ideal temperature
  • No need for batteries
  • Firmly fits on the tank glass
  • Quite fragile and easy to break
  • The suction cup can possibly damage acrylic tanks

9. Jansamn Adhesive Strip Aquarium Thermometer

Strip Adhesive
Jansamn Thermometer

Jansamn Thermometer

This is a sensitive stick-on aquarium thermometer strip that’s quite easy to install, only requiring you to peel off the back seal which exposes the adhesive and is then stick to the tank.

It gives a fairly accurate temperature reading both in ˚C and ˚F having a range of values from 4˚C to 36˚C and 39˚F to 97˚F. The larger numbers on the strips give the reading in ˚F while the smaller numbers give the reading in ˚C.

It has a color marking which shows the current temperature reading. However, if it shows multiple colors, the average value should be calculated and chosen.

It comes with a fairly cheap and pocket-friendly price tag too, making it a great choice for a low budget device.

Sadly, it does not glow in the dark which makes it difficult to read off the temperature values without the aid of an external source of light. It can also be a bit difficult reading the values during the daytime too.

  • It is suitable for constantly monitoring the temperature changes
  • Quite cheap and pocket friendly
  • Has an easy-to-read off numbers
  • Fairly accurate
  • Difficulty to read values without an external light source

10. Keynice Aquarium Digital Thermometer

Temperature Sensor USB
Keynice Digital Thermometer

Keynice Digital Thermometer

Keynice Digital Thermometer is a great multi-purpose device, suitable for aquariums, pet homes, cars, and computer appliances.

It has a unique design that allows it to be surface or flush-mounted. However, it would require a mounting hole for this purpose.

It shows a clear temperature reading designed with a graphical display to indicate for low, normal or high temperature.

It is highly accurate, displaying temperature readings both in ˚C and ˚F with -/+ 1 degree deviation.

Rather than a battery-powered functionality, it is designed with a USB power source which requires it to be plugged to a USB extension before it can be used.

This makes it an ideal thermometer for many applications not just for aquariums.

  • Has a graphical display for temperature intensity
  • Displays readings both in ˚C and ˚F
  • Does not require a battery, rather USB powered
  • Highly accurate with -/+ 1-degree deviation
  • Can be surface or flush-mounted
  • Excessively bright display which cannot be dimmed
  • The temperature probe could be longer

To conclude

The usefulness of the best aquarium thermometer in our tanks cannot be over-emphasized. The thermometer will help to maintain the perfect home for your aquarium fish offering them the comfort of their natural habitat.

It also ensures that the aquarium species live in an environment that would not impede on their health and would allow them to live a longer and happier life.

From our reviews, the Zacro LCD Digital Aquarium Thermometer is the perfect thermometer for a wide variety of aquariums.

This is because it is highly accurate compared to most thermometers having a -/+ 0.1 degree deviation tops.

It also has a wide range of temperature values spanning from -50˚C to 70˚C and the high-quality waterproof probe which gives temperature values both in ˚C and ˚F.

Top of it all, it is fairly cheap and pocket-friendly.

Frequently asked questions

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

Several aspects must be taken into account when placing the aquarium thermometer. If it’s an aquarium thermometer one, then the best place to put it would be in the opposite corner of the aquarium heater.

A stick-on aquarium thermometer should not be place close to any cooling or warming source as this can greatly influence its readings.

Are stick on aquarium thermometers accurate?

Generally, the stick on aquarium thermometers are not the most accurate, although they have the coolest look.

How do you use and install a digital aquarium thermometer?

Digital aquarium thermometers are fairly accurate and easy to install. They usually come with a probe that will be placed in the aquarium permanently. Through the wire, the thermometer readings will be displayed on the external LCD that’s placed on the tank glass using a suction cup.