Choosing the best aquarium thermometer is essential because it will allow you to keep your aquarium’s temperature precisely.

When you maintain the right water temperature in your tank, you can provide your fish with the best conditions to grow and be healthy.

This guide will highlight some of the best aquarium thermometers available on the market today.

We have skimmed a plethora of online reviews and assess different options in person to provide you with the best information available.

Comparison Chart

Products Type Power source Wire length Dimensions

Electric probe thermometer Batteries 24 inches 5.75×4.57×1.26 inches

External thermometer Batteries None 3x3x0.3 inches

Hanging thermometer None None 9x2x0.5 inches

External thermometer Batteries None 5.5×3.4×0.7 inches

Electric probe thermometer Batteries 28 inches 6×1.25×8.25 inches

Best Aquarium Thermometers Reviewed

1. Neptonion Aquarium Thermometer


  • Features a clear LCD that is visible even at a distance
  • Comes with a suction cup
  • It runs on batteries
  • Comes with a 24-inch long wire
  • The device is easy to set up


  • Batteries tend to run out fast


This is the best fresh and saltwater aquarium thermometer that you will find on the market today. It comes with a long wire measuring 24-inches, allowing you to comfortably place the probe inside the tank at any depth and measure the temperature with ease.

Moreover, the accurate aquarium thermometer is one of the most accurate devices for measuring your fish tank’s temperature. The readings are accurate and come with a feature that allows you to enter the units according to your preferences.

This fish tank thermometer can measure temperature readings between -58F to 158F, and its working temperature range is between -50F and 140F. Therefore, it’s an excellent choice for a wide variety of fish and tanks.

You will only have to deal with a margin of error that ranges between +/-1F, so the device is accurate. Setting it up is not a big deal as it comes with a couple of suction cups that still allow you to attach the probe inside the tank and attach the display outside of it.

The LR44 batteries that power this device do provide you with a pretty good backup time. But if you are looking for something even better than you should consider going for a unit that runs on the main power supply.


The digital aquarium thermometer is easy to set up and use, and it is the best aquarium thermometer on the market. It features a clear display and runs on two LR44 batteries. They provide you with a decent backup time, but they still are no match for a primary electrical power source.

2. Capetsma Aquarium Thermometer


  • Aquarium thermometer has a large digital display
  • Conveniently sticks to the outside of your tank
  • It runs on a couple of CR2 batteries
  • Doesn’t come with any probes or wires at all
  • Simple installation
  • Suitable for a variety of water types


  • Requires a steady room temperature to display accurate temperature


Are you tired of the wires getting tangled everywhere in your room? If you are looking for an external wireless aquarium thermometer, you don’t need to look any further. This device is the best option for you to consider because it is easy to install due to its stick-on design. It can also provide you with highly accurate readings in no time.

You only have to make sure your room temperature stays steady at all times because the readings of external aquarium thermometers can be directly influenced by the surroundings significantly. Therefore, if you will use this temperature for the best results, consider maintaining your room temperature where the aquarium is placed.

You can get accurate temperature readings to 0.1°F. This timer displays both 0°C to 70°C and 32°F – 158°F temperature.

Furthermore, this time is very easy to operate. All you have to do is to pull down the battery cover well below the screen. Now insert the battery, slide up the cover and stick it on the tank.

One of this external aquarium thermometer’s best features is running on a couple of CR2 batteries. Therefore, its backup is going to be pretty good. So you won’t have to consider replacing your batteries any time soon.

Moreover, you won’t have to deal with any probes or wires. Just stick the device on the outside of your tank, and it will start working immediately. It has a clear display, and you won’t need to have a second look at the display to get it right.


The external aquarium thermometer is easy to use, and you don’t even have to place it inside the tank. Just stick it outside the tank, and you won’t deal with any wires or probes. It’s not built for any particular water type or specific reptile. You can use it for fish, lizards, or turtles in freshwater, tap water, or marine water.

3. Landen Aquarium Thermometer


  • Very easy to set up due to the hanging-on design
  • Does not require batteries or any external power sources
  • Has a very minimal design made of crystal clear design
  • Suitable to be used in all water types


  • The size is too small, and you can’t see the reading from a distance


Do you prefer manual devices instead of automatic ones? If so, get a Landen thermometer for your fish tank.

This is a very compact-sized aquarium thermometer that is designed to provide you with convenience. There is nothing complicated in installing this thermometer to your tank because you just need to hang it on the edge of your tank.

It will continue to provide you with the readings of your aquarium’s temperature with ease. However, it does not come with any large display, and you have to hold the analog thermometer in your hand to see the reading.

It’s effortless to operate. All you have to do is place it parallel to the fish tank for 60 seconds, and the gauge will start moving and reach the current level of temperature. You can simply read the temperature against the conventional gauges.

The temperature reading is accurate, but we recommend that you use it with another digital thermometer to measure the temperature at the tank’s depth. This unit is ideally suitable for smaller tanks. If you have a large tank, you need to go for more than one thermometer in your tank for a more consistent and accurate reading.

The best part is that you can conveniently use this marine thermometer in both saltwater and freshwater with ease. No type of water will ever cause any wear and tear on it.


An analog thermometer is a great choice for users who want a simple piece of equipment to measure the tank’s water temperature. You need to hang it on the tank edge, and it will let you know the reading is a brief period. This device is ideally suitable for smaller tanks.

4. Qguai Aquarium Thermometer


  • External aquarium thermometer is suitable for all tanks
  • Large LCD allows you to read the temperature from a distance
  • Doesn’t feature any wires or probes
  • Simple to install and control
  • It runs on a couple of CR2032 batteries


  • Not suitable in rooms with inconsistent temperatures


The external aquarium thermometer is a top choice for anyone looking for an aquarium thermometer that is simple to install and use. When you stick it to the outside of your tank, it will start displaying your tank’s temperature.

You have to make sure that the room you have placed your tank in has a very consistent temperature range. If there are too many sudden temperature fluctuations in your room, this thermometer will begin to malfunction.

This is one of the reasons why external aquarium thermometers are not that popular. Otherwise, if you have a steady room temperature, this type is the best to use as you won’t have to deal with any cables, wires, or thermometers probes.

Just put the cell in, cover the lid and tick hot on the outer side of the tank. It will begin to display the temperature right away. It will display the accurate temperature of your tank.
The digital fish tank thermometer is easy to use and has a simple control to set the temperature for the highest and the lowest range. The more significant number will display the current temperature of the tank.


If you prefer external thermometers and don’t have too many temperature fluctuations inside your room where you have your tanks placed, this is the best thermometer you can use for your aquarium tank.

5. Lifeguard Aquarium Thermometer


  • Long-lasting battery life
  • Pretty simple installation
  • A huge-sized digital display
  • It also comes with an alert feature
  • It can provide you with room temperatures as well as tank temperature
  • Highly accurate measurements
  • Very easy to use and read
  • Straightforward controls


  • The temperature readings are not consistent at times
  • The probe cable length is on the smaller side


This is a unique electric probe aquarium thermometer because it can measure your room and tank’s temperature.

It means you can have a better analysis of what is making any temperature changes in your tank. Moreover, this device will display time and give an audible alert when the temperature exceeds the range.

The controls present on this device are pretty simple to use, and you don’t have to go through a lot to set the range according to your requirements.

Some people have complained about the readings being around 4F to 5F off. But you can conveniently manage that by simply lowering the probe deeper into the water. Having it closer to the surface will cause some problems.

A small desk stands at the back of the display, allowing you to place it conveniently on the tank or nearby table. The thermometer device runs on a AAA battery so that it can last for a long time. Moreover, this device is designed to be used in both saltwater and freshwater tanks. The box will also include a diction cup for the probe.


This device is simple to install and use, and it will continue to display both internal and external temperatures of the tank. It also shows time and can issue audible alerts for you once the set range is exceeded. If you have a significantly varying temperature in your room and you have a fish tank there as well, then you will find this thermometer ideal. It also runs on a AAA battery, so it will last for a long time to come.

Do I Need an Aquarium Thermometer?

An aquarium thermometer is an essential tool because it will allow you to monitor your tank’s temperature so you can maintain your tank’s temperature according to the life you have in it.

Although many tank fish can survive between 75-80°F, it can still vary according to the fish type. Different fish species need different temperatures; some live in cold water while others exist in slightly warm water.

For example, a goldfish need temperature below 70°F, while an average tropical fish can survive 75-80°F. A temperate fish needs a habitat that overlaps cold-water and tropical temp.

– Eliminating the Guesswork

One of these thermometers’ best features is that they eliminate any guesswork from your tank temperature. You will know exactly (or with very close proximities) what the temperature is. An underwater thermometer will allow you to have different types of fish accordingly.

– Maintain the Conditions Better

It will enable you to identify if your tank has any issues in its working. So, having this aquarium thermometer can be very beneficial in effectively maintaining the conditions in your fish tank.

– Prevent Temperature Shock

Moreover, having an aquarium thermometer in place will ensure that you can protect your fish from any temperature shock. Your aquarium fish are prone to temperature shock.

a) Cold temperature shock

If the water gets too cold, your fish will become lethargic. When the temperature of their surrounding water is low, they will stop swimming and lay on the substrate at the bottom and eventually get comatosed. You can gradually increase the water temperature by adding warm water.

b) Hot temperature shock

On the other hand, fish also have to deal with temperature shock if the temperature gets too high. They begin to breathe rapidly and come to the surface of the water. Warm water cannot hold much oxygen, and fish will suffocate. They will try to stay close to the water’s surface because there is a small pocket of oxygenated water that fish will try to use.

Some fish will even begin to swim faster than usual, and they will show erratic behavior. With the increased amount of energy, stress increases and weakens the immune system. Therefore, your fish will begin to face health issues. You can add colder water gradually to correct the temperature level.

Buying Guide

You need to consider various features if you are looking to go for the best aquarium thermometer. It needs to be the right kind for your fish tank, and of course, accuracy should be there because there is no point in buying a thermometer that cannot give you an accurate reading of the water in your tank.

1. Types

First of all, let’s briefly look at the different types of aquarium thermometers that money can buy. There are different kinds of thermometers in terms of design. Some are digital, some are analog, some float, which others stick into the rocks or gravel at the bottom.

Additionally, there are sticker thermometers as well, but they are not highly accurate. Flexed and wired footing thermometers are there too. But primarily in terms of functions, there are three broad categories and how they work.

– Digital

A digital thermometer features a probe that is connected with a digital display. This device measures temperatures in Fahrenheit and Celsius with high accuracy. Some of these thermometers can be left inside the tank for a more consistent monitor, while some modes come with an inbuilt alarm to alert you when the desired temperature is reached.

– Floating/standing

You can also go for a floating or a standing thermometer that can be completely submerged in the water. Due to this, you might find it difficult to read the temperatures from them.

These devices are made of glass, and you can place them either with suction cups or magnets. These devices are cheap, and you can go for more than one in especially in larger tanks, to get an accurate reading.

– Electric

You can comfortably place this type of thermometer near the surface or make it go down deep. However, the digital display is not waterproof, so make sure to keep it outside of water. Some of them are battery operated, while others need to be plugged directly into the main switch.

– Stick-on

These devices are stuck on the outside of the tank, so their accuracy level won’t be that reliable. Apart from that, room temperature can also influence their temperature reading. However, these are the easiest to read and control. But make sure your room temperature stays regular and consistent at all times.

2. Accuracy

The best aquarium thermometer is always an accurate one. If a device is not accurate, then there is no point in buying one in the first place. It needs it to be accurate within +/-2°F at minimum. With high accuracy, you will check the temperature and make adjustments to it accordingly.

3. Durability

Make sure that the thermometer that you are using for your tank is durable. If it is not, it will break inside your tank, and you might have to do a clean up. Durable thermometers will cost more, but they will deliver value in the long run.

4. Easy Reading

One of the most important features that consumers frequently ignore is the easy readability of a thermometer. This is especially the case if you are using a fully submersible thermometer.

If you can’t read it properly, you will have great difficulty finding the right temperatures, which means that knowing the aquarium’s right conditions will become problematic.

The best option for you to try is the digital thermometer because it is far easier to read, allowing you to promptly make the necessary adjustments. These digital models are expensive, but they also worth the money in the long run.

5. Power Mode

Some of these devices are directly powered by an electrical outlet, while others run on batteries. Using a battery-powered thermometer can be convenient, but the batteries can run out fast.

In most cases floating, stick-on, or standing thermometers don’t need batteries to run, and they serve as a good backup option for your digital thermometer.

6. Installation

You also need to make sure the thermometer device you are looking to go for is simple to install. It needs to have a design that allows you to place it in your tank. But some digital models do need some additional steps for you to execute for the full installation.

But make sure that these additional steps shouldn’t require a technical hand from your side. Some of them only require to be connected with the tank. While others need to be stuck on the tank and start working immediately. Just make sure you don’t have to go through a lot when it comes to installation.


There you have it. Now you know everything you should know before picking the right thermometer for your fish tank.

In our opinion, the best aquarium thermometer that money can buy is the Neptonion Aquarium Thermometer. It comes with a very user-friendly design, and you can conveniently read the temperature on it from a distance.

Installation is simple, and you only have to lower the probe that comes into the tank and start measuring the temperature right away. Its controls are simple, and you can use them on a larger tank if you want.

5/5 - (15 votes)


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