The 4 Best Fish Tank Thermometers You Should Spend Your Money On

fish tank thermometers
Care & Maintenance

There are numerous fish species you can rear in your fish tank, and some are sensitive to cold and heat. And with such fish in your aquarium, it would be a mistake to depend on your home’s heating system. You will need a fish tank thermometer so that it is easier for you to keep tabs and regulate your fish tank temperature efficiently. You might think that your aquarium is conducive, but when the water temperature is unsuitable, this could have devastating effects on the aquatic life in your fish tank.

When looking for the best aquarium thermometer, there are numerous attributes you must take into account as well as have in-depth knowledge about aquarium thermometers. Before we can review our top 4 picks for aquarium tank thermometers, let’s first look at the types of fish tank thermometers the market has to offer.

Types of Fish Tank Thermometers

There are three basic fish tank thermometer types: stick on, standing/floating on water, and digital thermometers.

Stick On Thermometers: This is the most widely used type of thermometer in freshwater fish tanks, and it often comes as part of your new fish tank. These thermometers have dual Celsius and Fahrenheit scales, and the range varies between models. Most of these thermometers come with a horizontal scale though few have horizontal ones.

Standing/Floating Thermometers: These floating or standing thermometers are placed in the fish tank, providing a more direct measure of water temperature. These thermometers come in different styles: there are those which stick to the aquarium side, those that float around the water, and those that hang with a clip.

Digital Thermometers: These digital thermometer types have a probe placed in the aquarium, either temporarily or permanently, which then connects to a digital display outside the tank. Some digital fishing thermometers connect wirelessly whereas other types will have a cord linking the display to the probe.

Reviews For The Top 4 Fish Tank Thermometer

1. KollerCraft TOM Digital Thermometer

The KollerCraft Tom water tank thermometer can be used in saltwater and freshwater aquariums. One impressive aspect of this thermometer is that it has a temperature alert feature that alerts you to a temperature drop through an audible alarm. Besides having suction cups that let you stick it on the outside of your aquarium, this fish tank thermometer also comes with a 3-foot cord which makes it easy to place your thermometer at any point. With a scale ranging from 75 degrees F to 82 degrees F, this piece of thermometer guarantees accurate temperature readings.


• Easy to use
• Ideal for saltwater and freshwater aquariums
• Provides accurate temperature readings
• Audible notification alarm


• Temperature could be off by about 3 degrees F

2. Zacro LCD Digital Thermometer

This thermometer is made with an LCD which is easy to read and displays temperature readings in Fahrenheit or Celsius depending on what you prefer. This thermometer is powered by a single battery that has a long lifespan and is easy to replace when the charge is drained. Besides having a temperature range of -10 degrees to +50 degrees, this thermometer lets you take temperature readings within 0.1 degrees. For accurate readings, you only need to submerge the probe into your fish tank.


• An easy-to-read LCD
• Offers accurate temperature readings
• An easy-to-operate thermometer
• Has a compact design


• The water thermometer has a loose battery connection
• Slow at recording temperature changes

3. Fluval Aquarium Thermometer

If you are looking for a slim and compact fish tank thermometer that offers accurate temperature readings, then this is what you need. Its compact design is attributed to the fact that it does not use any batteries. And unlike other aquarium thermometers, this model has a gel-like substance that reacts with temperature and changes its color based on temperature. The temperature range for this thermometer is between 64 and 86 degrees F, which is ideal for most fish tanks.


• Has a compact design
• This thermometer is affordable
• It is small hence will not be too obstructive for small fish tanks
• No battery needed


• It is not as accurate as it should be
• Its temperature range is narrow

4. American Thermal Horizontal Thermometer

Weighing 0.3 ounces and measuring 0.75 by 4.25 inches, this thermometer is designed to go inside your fish tank and beneath the waterline and is attached horizontally using an adhesive. Unlike other thermometers that use electric probes with an LCD, this thermometer has small color-changing crystals that indicate a small temperature change. The color is then compared to a color chart, and the accurate water temperature can be obtained.


• Offers accurate temperature readings
• Easy to read
• Color changing crystals are extremely sensitive to temperature changes
• Sticks on the inside of your aquarium


• The adhesive could be weaker
• There are no alerts on temperature changes

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