If you’re thinking that the temperature in the aquarium isn’t really a matter of concern then you need to rethink, my friend. The temperature of the aquarium is an immensely important factor as that plays a vital role in keeping the fishes healthy and happy inside the aquarium.

Having a temperature too hot or too cold will have a negative impact on the aquatic creatures inside the tank. It’s extremely important to have a heating system in the aquarium when you have tropical fishes. Sometimes the reading on the heater isn’t accurate so it’s a must to have a proper aquarium thermometer that will give you accurate and correct readings.

There are many aquarium thermometers available out there. But, it’s important that you get your hands on the one that provides the most accurate reading in order to keep the optimum temperature inside the fish tank. Let’s take a quick look at our top picks for the best aquarium thermometer.

Most Accurate Aquarium Thermometers At A Glance

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What is an Aquarium Thermometer?

Like every other thermometer, the main purpose of an aquarium thermometer is to measure the temperature. This device comes really handy when you’re trying to create an ambient atmosphere for the aquatic species inside the tank.

Sometimes the heaters aren’t 100% reliable, so in situations like those, this bad boy comes into play and saves the day. Some of the aquarium thermometers even have an alert system that will notify you when the fish tank temperature goes up or down the optimum temperature.

Top 7 Best Aquarium Thermometers Reviews

1. VEE GEE Scientific Ultra High Accuracy Digital Thermometer – Most Accurate Aquarium thermometer

VEE GEE Scientific Ultra High Accuracy Digital Thermometer

If you’re looking for a budget-friendly digital aquarium thermometer that provides high accuracy then give VEE GEE Digital Thermometer a try. The temperature is shown in °C &°F so that get a clear idea about your desired temperature.

The temperature range lies between -10 to +100°C / +14 to +212°F. Also, the accuracy comes with a range of 0.1° / ±0.5°C & 0.1° / 1.0 °F. This aquarium thermometer would be an excellent choice if you have a tank for tropical fishes which require a warm temperature setting as it can measure up to 100°C.

It includes a moderate size viewing display that enables you to quickly check the temperature reading. One of the best features of this LCD digital aquarium thermometer is that it’s equipped with an LR44 battery that provides a very long lifetime.


The VEE GEE LCD digital aquarium thermometer has a very compact size. It weighs only 1.38 ounces which wouldn’t occupy much space in the tank. Also, it comes with an easy turn on and off button which makes it super easy to use.

  • Budget-friendly
  • Provide a high level of accurate result
  • Both °C &°F temperature scales are included
  • Have a long battery life
  • Easy to turn on and off
  • Compact size with digital display
  • No alarm feature

2. Cooper-Atkins Waterproof Reduced-Tip – Best Digital Aquarium Thermometer

Cooper-Atkins Waterproof Reduced-Tip Digital Thermometer

Cooper-Atkins are known for creating top-notch thermometers and this one is surely one of their finest creations. It measures the temperature condition with utmost precision.

The Cooper-Atkins Waterproof Reduced-Tip LCD Digital Aquarium Thermometer can effectively measure from -40 to 450 F. It’s approved by the Original Equipment Manufacturer and the parts of this aquarium thermometer are easily replaceable.

It has a very compact size and setting up this LCD digital aquarium thermometer is easy as a breeze. Being a digital aquarium thermometer it clearly shows the temperature of the fish tank water and doesn’t let the temperature outside have any effect on the result.

This thermometer doesn’t need to be entirely submerged in the water. All you need to do is to keep the external sensor submerged in the tank for a few seconds and it’ll provide you with an accurate result.

  • Easy to read out results
  • Only the external sensor needs to be submerged
  • Gives accurate result
  • OEM approved
  • External environment doesn’t hamper the result
  • No alarm or alert system included

3. JW Pet Company Smarttemp – Best Analog Aquarium Thermometer

JW Pet Company Smarttemp Thermometer

You’re probably thinking that good aquarium thermometers come with an expensive price tag. However, it’s not true when it comes about the JW Smarttemp. It provides a highly accurate result and its incredibly pocket-friendly price makes it quite a steal.

If you’re looking for a great submersible aquarium thermometer that will stick to its place without constantly getting drifted away from its place then give the JW Smarttemp Thermometer a try. It has unique magnetic technology that keeps the thermometer attached to its designated place.

You don’t need to use a suction cup to hold it in place. This fish tank thermometer provides a highly accurate result. It is not digitalized and you have to manually figure out the number looking at the thermometer.

Most glass bottles are hard to read out when they are submerged in water. However, JW came up with unique technology and they used plastic instead of glass which makes it easily readable even from distance. There’s a green zone marked which shows the sign for optimal temperature range.

  • Affordable
  • Provides accurate result
  • Held by a magnet to the tank of the wall
  • Large easily readable numbers
  • Not digital display
  • Numbers might seem hazy from distance

4. Inkbird ITC-308 Temperature Controller – Best Aquarium Thermometer With Alarm & Heater Controller

Inkbird ITC-308 Temperature Controller

The Inkbird ITC0308 can be easily called the superman of the aquarium thermometers. In fact Inkbird ITC-308 is a dual stage, pre-wired Digital Temperature Controller. You may also call it an over-riding thermostat.

It is much more than just a simple aquarium thermometer. It can control both the heating and the cooling device to maintain the optimum predefined temperature in your aquarium. Inkbird consists of a temperature probe that goes inside the tank, a digital display unit with setup buttons and two power outlets labeled as “heating”and “cooling”.

You can program this controller with your desired temperature and set a threshold level. Whenever temperature goes down the threshold it powers up the heater and when temperature goes up it turns on the chiller. So you will get a complete hands-free setup to maintain an optimum environment in your fish tank.

The price of this device is on the steeper side. However, that is understandable considering the number of features it provides. Its built-in alarm will even notify you if the sensors aren’t working. No doubt this is the best aquarium thermometer considering all these amazing benefits you will get.

  • An alarm system that will notify it the temperature rises or falls
  • Clear digitalized screen and programming buttons
  • Measures temperature accurately
  • Controls temperature at your desired level if integrated with chiller & heater
  • Notifies if the sensors stop working
  • Expensive (obviously)

5. Thomas Traceable Long Stem Digital Aquarium Thermometer

Thomas Traceable Long Stem Digital Thermometer

If you’re looking for a hassle-free thermometer with top-notch accuracy then get your hands on the Thomas Traceable Long Stem Digital Thermometer. It comes with a 0.4″ display that shows the temperature in clear numbers.

This thermometer features both °C and °F temperature scales. It measures temperature from -50 to 150 °C with an accuracy of + or – 1 °C. It’s powered by a silver oxide battery with a large battery life.

Being a long stem thermometer, it needs to be operated manually. However, as it provides a digitalized number, reading out the result is quite simple and easy. You can pick from both °C and °F, whichever you’re comfortable with.

To use the thermometer, take off the cover and turn it on. This thermometer includes an 8″ stem that needs to be submerged in the water for a few seconds in order to obtain the result. The stem is absolutely rust-free and it provides results with a high level of accuracy.

  • Easy to use
  • Large stem
  • Digitalized result
  • Temperature scale both in °C and °F
  • High level of accuracy
  • Expensive
  • No alarm or alert system

6. LCR Hallcrest Liquid Crystal Vertical Aquarium Thermometer – Best Cheap Thermometer For Fish tank

LCR Hallcrest Liquid Crystal Vertical Aquarium Thermometer

In case you’re looking for a super budget-friendly thermometer with outstanding performance then think no more and get yourself the LCR Hallcrest Liquid Crystal Vertical Aquarium Thermometer. The main purpose of getting a thermometer is to get an accurate temperature reading and this one does that with utmost precision.

This thermometer is super easy to use and it doesn’t require any power to run. It’s a stick on thermometer which means you have to simply stick on the outside of the tank wall to get the temperature reading.

The stick on thermometers is also known as LCD thermometers. They are an absolutely hassle-free and charm to use. The LCR Vertical Thermometer can be placed anywhere in the tank so that you can the most accurate result.

Stick on thermometers tend to alter the result and they don’t provide the exact temperature reading as they are placed outside the tank. However, if you’re on a tight budget or don’t want to splurge on a thermometer then do give this one a try.

  • Very inexpensive
  • Easy to use
  • Doesn’t rinse off while cleaning the tank
  • Results are easily readable
  • The result is not very accurate

7. Zacro LCD Digital Aquarium Thermometer – Best on the budget with lCD display

Zacro LCD Digital Aquarium Thermometer

The Zacro LCD Digital Aquarium Thermometer is another super inexpensive thermometer that provides quite accurate readings. Despite the small price tag, Zacro made a decent quality product.

This thermometer comes with an easily readable LCD display. There’s a cable attached to the probe which needs to be submerged in the water to get the readings. Operating this thermometer is quite easy. All you need to do is to attach it to the outside of the tank with a suction cup and submerge the probe in water.

There’s a power button switch which will immediately turn the device on with a press on the button. If you want to turn the device off then press the power button for 3 seconds and it’ll automatically shut down.

The Zarco LCD digital aquarium thermometer is equipped with a LR44 battery. Before mounting it to the aquarium wall, take off the battery cover and insert the battery with the positive sign up and the LCD will show the ambient room temperature if the battery is put on correctly.

  • Affordable
  • Gives quite accurate result
  • Long battery life
  • Easy to mount on the tank wall
  • Clear LCD display
  • Floating thermometer with suction cup
  • There will be some error margin in the reading

How to Choose the Best Aquarium Thermometer?

Well, now that you have taken a look at the best aquarium thermometers out there, it’s time to make the ultimate decision. However, before making the purchase there are several factors you should consider so that you get the best value for your money.

Best Aquarium Thermometer

Types of Aquarium Thermometer

There are several types of aquarium thermometers available. Not all will provide the same kind of accuracy so get the one that’s suitable for your tank and fish type.

Digital Thermometer

The digital aquarium thermometers have a digital display unit which is kept outside of the tank with a probe submerged in the water. Digital thermometers come in both with wire and wireless model.

Digital thermometers are known to provide highly accurate readings. The probe of the thermometer is submerged in the water. Many of them include an alarm system which goes on if the temperature exceeds or decreases than the optimum one.

The temperature reading is very simple in these thermometers as they come in either in Centigrade or Fahrenheit scale. The only drawback of these thermometers is that they are more expensive than the other variants.

Additional Read: Best Aquarium Heater Controller

LCD/Stick on Thermometers

The stick on or LCD thermometers are super inexpensive and the best part is that they almost never break. These thermometers have a thin LCD strip that hangs outside the tank. They are also quite easy to read out due to the LCD display.

The downside with these thermometers is that as the stick hangs outside the wall of the tank, sometimes they don’t provide an accurate result as the outside temperature tends to affect it. Make sure you don’t place the stick under direct sunlight or heating devices as that might alter the result.

These thermometers don’t feature any alarm setting so you have to manually check whether it’s on the optimum temperature or not.

Standing/Floating Thermometers

The standing or floating thermometers are the analog thermometers which need to be fully submerged in the water in order to get a correct result. They stay put with the help of a suction cup. The result provided by these thermometers is highly accurate as they are entirely submerged in water. Therefore, the temperature outside doesn’t have any role to play in the overall result.

The cons with these thermometers are that they are quite hard to read. There’s no alarm system in them as well. Also, they are quite fragile as they are made of glass so it might break inside the tank which may create quite a mess. Sometimes the suction cup is not good enough and looses temper with time.

Ease of Use

Make sure the thermometer you buy is easy to use and doesn’t have any complicated setting. The more complicated the device is, the more likely it is to wrong. A complicated thermometer will take more time to install and interpret the result. So, get an aquarium thermometer that has an easy installation process with an easy operating system.


Durability is a prime concern for all sorts of products. The thermometer may give you accurate results but if it’s not durable then it’s not worth spending the money. It will be extremely dangerous for the fishes if the thermometer submerged in the tank breaks as the chemicals from it will have severe impacts on their health.

Also, it’s vital that the thermometer provides longevity. This is not an equipment you’d like to buy every now and then. So, read reviews, ask for suggestions from aquarists and analyze the product before making the ultimate purchase.


The sole purpose of getting an aquarium thermometer is to measure the temperature and what good would it be if it provides an inaccurate one? Not all thermometer provides an accurate reading and it’s extremely vital that you get a thermometer that provides you the correct reading so that you can create an ambient atmosphere for the fishes. Some fishes are very sensitive and a small change in the temperature can have a drastic effect on them.

Temperature Range

The temperature range of a thermometer is a very crucial factor to consider. Having a range too small will give you less flexibility. If you have fishes suited for tropical weather then get a thermometer with a larger temperature range. If your fishes are more suited to cold temperature then it’s better to get a thermometer whose temperature ranges below 20 degree centigrade.


No matter how accurate the thermometer is, if it can’t be read out from the display then it’s not worth the money. Get a thermometer with a clear display so that you can clearly understand the readings. Often times if the thermometer is submerged in the water then it’s hard to figure out the number. Make sure the thermometer features a clear display that can be read out even from distance.

What are the Benefits of Using an Aquarium Thermometer?

Aquarists are generally very concern about getting a heater for a tropical aquarium to provide the fishes with a comfortable environment. However, keeping a close eye on the temperature is just as important to prevent any fishkeeping disaster. Make it a habit to check the temperature at least once or twice a day.

Aquarium fishes need a favorable temperature in order to live a healthy lifestyle. Sometimes the temperature changes between day and night or the temperature fluctuation due to water change can be stressful for them. These changes can eventually lead to fatal diseases as well.

Sometimes there are incidents when the heater breaks and the temperature rises or falls down rapidly. If situations like this aren’t taken care of right away then they can create massive harm to the fishes or corals.

Nowadays there are many thermometers available and we have also reviewed quite a few that comes with an alarm system. The alarm system warns you when the temperature rises or goes down the favorable one.

Where is the best place to put a thermometer in an aquarium?

To get an accurate reading you should put the thermometer above the gravel line. Don’t place in near the surface level as it may have an impact from the ambient temperature. Also placing it near the heater may give you wrong or higher reading. So place it at the opposite site of your heater.

Frequently Asked Questions

Is there mercury in aquarium thermometer?

Mercury thermometers aren’t very common in aquarium thermometers. It mostly uses alcohol or colored dye. However, if the liquid in the thermometer is silver colored only then it’s using mercury.

No matter what substance is used for the liquid, it’s essential to move the fishes immediately if the thermometer somehow breaks inside the tank.

How do I read the Thermometer?

Reading an aquarium thermometer is easier than a regular thermometer. Stick on thermometers usually, have a red line which indicates the temperature. Also, most aquarium thermometer nowadays comes with digital LCD display which shows the temperature in clear numbers.

Do I need to put the thermometer inside the tank to measure the temperature?

There are lots of different type of thermometers. Some need to be fully submerged in the water, some of them include a probe that can be put in the water to measure the temperature and there is stick on thermometers you can stick outside the tank to measure the temperature.

Sometimes, the outside environment tends to alter the result. Make sure whichever one you choose, you get the most accurate result.

What temperature should my aquarium be?

It depends on the species you are keeping in your tank. You shouldn’t mix cold water fish with tropical ones in your aquarium. In general fish do best at a temperature range of 76-78F.

Final Thoughts

Fishes are very delicate species. They require just as much love and attention like any other house-pets. We tend to care so much about the heaters, filters and other stuff that we forget about the necessity of a good aquarium thermometer.

A good thermometer will not only help you create a favorable environment for the fishes but also save them from many fatal disasters. In this article, we have reviewed the best fish tank thermometers available in the market keeping in mind a wide array of users with different needs and budget. All the products that we reviewed are top-notch with outstanding quality.

Along with the important features, we have also included the pros and cons so that you can make the decision more easily. Hope this article will help you to create an ambient environment for the aquatic species in your tank.

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