The Fish Keeping & Aquarium Guide.

Most Accurate Aquarium Thermometer

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For fish to thrive in an indoor aquarium, it is vital to maintain the right water temperature. And, the best way to do that is to make use of an aquarium thermometer. If you want your fish to be healthy and happy, make sure you create the ideal environment for them, similar to water bodies such as oceans and lakes. As long as the fish tank temperatures are not suitable, they can get sick or even die. 

Therefore, you need to invest in a good-quality aquarium thermometer so that you can continuously check if the water inside the tank is at the correct temperature. Although some people rely only on a heater to control the water’s temperature, it is essential to remember that heaters do not always give accurate readings. You will also need a thermometer. 

Although small in size, the role of a thermometer in an aquarium can never overstate. Just be sure to buy a good quality thermometer, one that always provides accurate readings. 

Most Accurate Aquarium Thermometer

There are so many varieties of thermometers on the market nowadays that picking one can be quite tricky. The following are a few of the thermometers that you can consider.

1) Zacro LCD Digital Aquarium Thermometer

If you are a first-time aquarium owner, this would be the ideal choice, and this is because it is easy to use and is also long-lasting. It boasts of a big, clear, and simple to read display. In terms of scales, you can get it in Celsius or Fahrenheit form. 

It is also a good pick because of its suction cup feature. You stick the thermometer outside the aquarium, ensuring that the temperature probe is fully submersible in the water. People go for this thermometer type because it is entirely accurate when it comes to readings, providing temperature readings within +/- 0.1 degrees. The temperature range is between -50 to +70 degrees Celsius, so versatility is not an issue. Additionally, the long-lasting battery that powers it is a single LR44 button cell battery. 


  • Big and simple to read LCD display.
  • Low-priced.
  • Extensive temperature range and precise readings.
  • Temperatures precise to +/- 1 degree.
  • Measurements in 0.1 degrees.
  • It uses a single LR44 battery, which is easily replaceable.
  • Simple to install.
  • It comes with a convenient suction cup.
  • It comes with a submersible probe.
  • Simple to store because it is small and compact.


  • The suction cup might end up losing suction.
  • Loose battery connection.

2) Marina Floating Thermometer with Suction Cup

Another thermometer that is worth considering is the Marina Floating Thermometer. It is 4.25 inches long, and it floats vertically in the water. It also comes with a suction cup in case you prefer keeping it in place. It is relatively accurate when it comes to readings, and the readings are available as Celsius or Fahrenheit. 

You can use it in both freshwater and saltwater, and it comes with a visibly marked safety zone that will indicate the most suitable temperature range for a lot of tropical fish. It is a little bit difficult to read when compared with a digital thermometer. But it is usually way more accurate than individual inexpensive digital thermometers. 


  • Budget-friendly.
  • You don’t require a battery.
  • Suitable for freshwater or saltwater use.
  • Precise readings, simple to read, and available in Celsius and Fahrenheit
  • Has a safety zone indicator.
  • Your fish will be adequately protected y this thermometer from unsafe temperatures.


  • Suction cup leaves ring stains on acrylic tanks, and they are not easy to remove.
  • Because it’s small, it can be hard to see the readings.

3) JCreate Aquarium Thermometers

What makes this the ideal thermometer for some fish tank owners is that it comes with a very clear LCD screen that provides very accurate readings. It is also compact and has a modern red and black design. There is no need for probes or other wires. It comes with a backside temperature sensor, which you stick on the outside of the tank. This sensor plays a vital role in preventing electronic oxidation and water infiltration. It is easy to read from afar due to its big crystal touch screen. To set up the flash function, you can make use of the touch screen. The flash function is crucial because it immediately flashes a light when the temperature is no longer within a suitable range. 


  • Transparent screen and big numbers make it easy to read.
  • No wires and probe.
  • Flash function.
  • Accurate measurements (0.1 degrees).
  • Touch screen.
  • Easy to use.


  • Without proper lighting in the tank, the transparent display might be difficult to read.
  • Short battery life.

Various Kinds of Aquarium Thermometers

1) Digital Thermometer

In terms of price, this is the most expensive thermometer on the market. It features a digital display unit, which is quite simple to read. You can go for either the wire or the wireless type. The display unit’s location is placed outside the tank, while the probe is inside the tank.

One of the main benefits of using a digital thermometer is that it comes with an alarm that rings when the water temperature is no longer ideal for the fish. Also, because the temperature readings are either in Fahrenheit or Centigrade, anyone can use this thermometer. 

2) Stick-On Thermometer

Another thermometer that some fish tank owners prefer is the Stick-On thermometer, also known as the LCD thermometer. They come with a thin LCD strip, which you hang outside the tank for easy reading. 

It is the best option for someone who is working on a budget since they are relatively inexpensive. And even though the stick-on thermometers are reasonably priced, they are quite durable. The only disadvantage is that, because the strip hangs outside the tank, this can sometimes affect the reading of the water inside the tank; the readings are affected by the outside temperature. 

So, if you choose this thermometer, there are chances that you will sometimes not get accurate readings, especially if the strip is near a heating unit or expose to direct sunlight. Also, because it does not have an alarm, manual check-ups must ensure that the water is at the perfect temperature. 

3) Standing / Floating Thermometers

In terms of providing accurate temperature readings, this is one of the best options for a fish aquarium because it is fully submersible in the water. Being completely submerged in the water allows for the most accurate readings because outside temperatures do not affect the thermometer. 

The complete submersion of the thermometer in the tank also makes it difficult to read. However, you could find one that comes with a safe zone of a different color, making it easier to see if the tank’s temperature is no longer safe for the fish. 

This thermometer uses glass material, so this is another issue that makes people hesitant to buy this thermometer. It makes them one of the most fragile thermometers on the market; they can easily break in the tank.

Some types require a suction cup to stay in place, and then some are magnetic. You can also opt for the kind that floats in the water or the ones that weight at the tank’s bottom. This inexpensive thermometer doesn’t feature an alarm system and is not the best option if accuracy aims.  

What to Look for When Buying an Aquarium Thermometer?

Before you buy an aquarium thermometer, just like with any new purchase, you should first check to see if it has all the features of a good quality product. It is wiser to make the final decision once you have considered all the relevant factors discussed in detail below. 

1) Accuracy and Range

One of the most important considerations when looking for a thermometer is its accuracy level, bearing in mind that the whole point of buying the device is to give you an accurate reading of the temperature of the water in the tank. The readings must also be within the range that is suitable for the fish. 

As for the actual readings, the range must be at least +/- 1 degree Celsius. It is vital to use a thermometer that gives accurate readings because some fish are quite sensitive to water temperatures. You have to make sure that the water in the tank is at the perfect temperature. 

When it comes to temperature range, make sure that the thermometer you opt for has a wide enough range for the fish tank. The ideal range would be anywhere from 50 degrees Fahrenheit (10 degrees Celsius) to around 104 degrees Fahrenheit (40 degrees Celsius). As far as accuracy is concerned, go for the digital aquarium thermometer with an LCD display. 

2) Durability

Another factor that you need to take into consideration when looking for a thermometer is durability. In as much as accurate readings are very important, if the thermometer you opt for is not long-lasting, it might not be worth to invest. Individual thermometers are more prone to breaking than others, such as the mercury thermometer. If it happens to break inside the tank, harmful chemicals may be released into the tank, putting the fish’s health at risk. 

Before you go for the cheapest thermometer you can find, make sure you do not substitute durability with the price. Go for the thermometer that is not only durable in terms of its materials but one that also has long-lasting battery life. 

3) Simple Installation and Easy to Use

Another issue that you have to take into account is the installation process. As you will be looking for an aquarium thermometer, make sure you choose simple to install and use. If you come across a complex to install brand and be confusing when it comes to readings, it is probably not the best choice for you. A good thermometer should be one that anyone can install and make use of with ease. Although you might come across digital thermometers that require a lot more steps when it comes to installation, the additional steps will not be necessarily complicated. 

4) Temperature Readability

What good is any thermometer if you cannot read the temperature? It would be best to buy a thermometer whose readings are visible even when it is entirely submersible in the water. In as far as readability is concerned, the best thermometer would be one that has a probe and LCD light. Just be sure that the one you choose has a clear display. 


Apart from providing a comfortable place for your fish to live in, a good quality thermometer will protect your fish from avoidable fatal disasters. You must take the temperature issue seriously because fish live longer when the water is just the right temperature for them. 

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