Updated September 11, 2018 by Joseph Perry

The 10 Best Aquarium Thermometers

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This wiki has been updated 14 times since it was first published in October of 2016. If you want your fish and other aquatic critters to thrive, then you must maintain a stable temperature in their environment. Aquarium thermometers are an easy way to do that and require little maintenance. From digital to old school displays and a variety of different mounting styles, there's sure to be one here that fits your specific needs. When users buy our independently chosen editorial recommendations, we may earn commissions to help fund the Wiki. Skip to the best aquarium thermometer on Amazon.

10. Zacro Digital

9. JW Pet Company

8. Pet Magasin

7. Corner Biz Aquarium

6. Lifegard Big Digital

5. BOYU BT-08

4. LCR Hallcrest A-1005

3. American Thermal BC002008

2. General Tools AQ150

1. Vee Gee Scientific

Keeping Your Fish Happy And Healthy

But why is the aquarium thermometer so important and will it help me keep my fish healthy?

Taking care of pets is a big responsibility. Large animals require a lot of human interaction and mental stimulation to keep them happy in their environments. That said, a smaller-sized pet doesn't necessarily require any less attention or monitoring. Sustaining aquatic life within an enclosed ecosystem, for example, carries similar responsibilities. In addition to maintaining a heater, constant awareness of the temperature inside your aquarium is integral to the health of your fish. In a natural ecosystem, a complex combination of weather, chemical, and geological processes have allowed animals to adapt to certain conditions over millions of years. By contrast, the aquarium isn't equipped with these natural processes, hence a fishkeeper's responsibility for keeping a closed tank system as stable as possible on their own. One way to do this is to monitor the tank's internal temperature using a thermometer.

In its most traditional form, a thermometer is a temperature-measuring instrument with a hermetically-sealed and graduated glass tube containing either mercury or alcohol. The mercury is designed to contract and expand from inside the tube as the surrounding temperature fluctuates.

But why is the aquarium thermometer so important and will it help me keep my fish healthy? Temperature accuracy and stability go hand-in-hand within a successful closed ecosystem. It's important to remember that an aquarium is artificial because it is man-made and separated from naturally-existing environments found in lakes or oceans. This means that, as a fishkeeper, you must recreate the same living conditions for your fish that they would ordinarily encounter when in their natural habitats. In order to accomplish this, both the aquarium heater and thermometer will be necessary to maintain temperature stability, while alerting you to potential problems before they become harmful to the animals. It's also important to realize that fish are cold-blooded creatures, which means they maintain the same body temperature as their environment. Therefore, major temperature changes can have a significant impact on their overall metabolism and ability to feed.

Three most common types of aquarium thermometer include stick-on, floating or standing, and digital. Also referred to as the liquid crystal display thermometer, the stick-on variety is the most inexpensive of all three options and popular for use in freshwater aquariums. As its name suggests, it "sticks" to the outside walls of a fish tank where it displays the temperature in a specific color.

Typically made from glass, floating or standing thermometers are placed directly inside the aquarium, which allows them to provide a more direct measurement of the internal water temperature. These thermometers can be equipped with suction cups for attaching to the inside walls of a tank, they can be suspended from a submerged clip, they can be left to float freely in the drink, and some are even equipped with weights for sinking to the bottom of an aquarium to "stand" and take more accurate readings.

Digital aquarium thermometers are battery-operated devices consisting of an external display that is directly connected to a probe placed inside the tank. Digital thermometers are usually the most accurate of all three types and can easily take readings from any location inside the aquarium.

Maintaining A Stable Mini Ecosystem

Always be aware of the optimal temperature ranges for the fish in your aquarium. For example, a neon tetra has greater sensitivity to temperature fluctuations and prefers an environment between 68 and 75 degrees Fahrenheit.

For example, a neon tetra has greater sensitivity to temperature fluctuations and prefers an environment between 68 and 75 degrees Fahrenheit.

Depending on the size of your aquarium and species of fish inhabiting it, you'll need to decide which type of thermometer is best. If you have large and highly-active fish swimming in your tank, a stick-on or digital thermometer will be a more practical and durable option than the floating variety. A major benefit to the digital thermometer is the convenient placement of its probe in virtually any location inside the tank. Its display is also unobtrusively mounted outside the aquarium. Many digital thermometers are also designed to display temperature values in both Fahrenheit and Celsius with an accuracy within 0.1 degrees. If you invest in a digital thermometer, make sure its display is backlit, so you can see it during the day and at night. Additionally, consider a thermometer with a built-in audible alert to inform you when the water temperature is too high or low.

Don't discount the floating thermometer from consideration, as many can be placed in multiple locations and are often equipped with colored bars indicating a safe temperature zone. While a floating thermometer isn't going to give you the same pinpoint temperature accuracy as the digital model, it's still an inexpensive alternative and a great choice for kids or those new to fishkeeping.

A Brief History Of Aquarium Thermometers

The earliest thermometers were actually referred to as thermoscopes, which were rudimentary thermometers without a scale. A thermoscope would only show temperature differences and not specific values. Galileo Galilei developed the first water thermoscope in 1593. Italian inventor Santorio Santorio was the first to put a numerical scale on his thermoscope by 1612.

Italian inventor Santorio Santorio was the first to put a numerical scale on his thermoscope by 1612.

It wasn't until 1714 when German physicist Daniel Gabriel Fahrenheit would develop the first modern mercury thermometer, followed by the introduction of his standard temperature scale in 1724.

The first medical thermometer used to take a person's temperature was invented by English physician, Sir Thomas Allbutt in 1867.

Following the growing popularity for the fishkeeping hobby after World War II, both the aquarium heater and thermometer became integral tools for sustaining aquatic life, as the aquarium thermometer could help inform how well the heater was keeping an accurate temperature.

Modern thermometers offer improved accuracy, compact size, and a wide selection of designs and placement options to accommodate fish tanks of any size or water type.

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Joseph Perry
Last updated on September 11, 2018 by Joseph Perry

An avid reader and outdoors enthusiast, Joe earned his doctorate in literary studies before making the lateral leap from academia to technical writing. He now lives and works in the inter-mountain West where he creates technical and marketing content, including white papers, solution briefs, and courseware for some of the world’s largest information technology companies. With more than 14 years of experience in the field, he has learned more than he ever thought he would know about such enterprise IT topics as cloud computing, storage, databases, business software, and networking. When he’s not writing about business computing, he can be found outdoors, probably hiking with his family and dog.


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