An aquarium thermometer is a crucial part of maintaining an optimal environment for your fish and other aquatic creatures.
Aquatic animals are highly sensitive to temperature and often require a very specific temperature range which should never vary by more than a couple of degrees at most.
Therefore, the ability to regularly and consistently monitor the temperature inside your aquarium is essential for ensuring the health of your pets.
However, there are many different kinds of aquarium thermometers, so it can be difficult to determine which one will be the best fit for your fish tank.
Luckily for you, we’ve done some research on these aquatic temperature-monitoring devices so you don’t have to! We’ve put together a list of the 5 best aquarium thermometers on the market, alongside a buyer’s guide and FAQ section to help you allow your fish to thrive.
If you’re in a hurry, why not take a look at our top choice? Marina Floating Thermometer with Suction Cup
- Fresh and saltwater compatible
- Floats inside aquarium
- 4.25 inches tall
- Easy to read
- Includes safety zone indicator
- Optional suction cup included
OUR TOP PICK
Topping our list is Marina’s Floating Thermometer with Suction Cup.
This aquarium thermometer is suitable for use in both freshwater and saltwater aquariums and is designed to float vertically in the water and provide a temperature reading.
A suction cup is also included so that it can be attached to the glass if desired.
At just 4.25 inches tall, this thermometer won’t take up too much space in your aquarium, leaving plenty of room for your pets to maneuver around it and go about their normal activities.
The analog display of the Marina thermometer is easy to read due to the clear temperature markings, with each horizontal line representing 1°C or 2°F depending on which system and side of the thermometer you read.
One of the best features of this thermometer is its safety zone indicator, marked out in green on the display, which indicates the safe temperature range for the majority of tropical fish.
- Suitable for both fresh and saltwater aquariums
- Includes suction cup for optional attachment
- Conveniently small (4.25 inches)
- Easy-to-read display
- Safety zone temperature indicator
- The suction cup may not work
This digital thermometer from Zacro has a lot of positive reviews because of how convenient and accurate it is.
Zacro’s aquarium thermometer works by using a probe which can be inserted into the aquarium to gauge the temperature.
The temperature reading will then appear on the digital LCD display.
The digital LCD display can give you a temperature reading in either Celsius or Fahrenheit, to 1 decimal place.
Moreover, the readings are quite accurate, deviating by just 1 degree.
This thermometer can be used to measure the temperature of both freshwater and saltwater, so it will be suitable for all aquarium types.
A suction cup is included on the back of the thermometer so that it can be attached to the outside of the glass for convenience.
When not in use, the display can be easily turned on and off using the single power button.
- Easy-to-read digital display
- Easy to operate using single power button
- Gives temperature reading to 1 decimal place
- Celsius and Fahrenheit readings available
- LCD battery included
- Suction cup included for exterior attachment
- The thermometer itself cannot be exposed to water
Capestma’s Digital Aquarium Thermometer is an incredibly convenient thermometer model that is as easy to read as it is to operate.
This thermometer can be used to measure the temperature of any type of aquarium, including freshwater and saltwater, due to the fact that it is designed not to come into contact with the water.
In order to use this thermometer, all you need to do is attach it to the outside of the aquarium glass using the adhesive strip.
The sensor on the back of the thermometer will then read the temperature of the water through the glass.
The reading can be given in either Celsius or Fahrenheit and is accurate to 0.1°.
You can even set your desired temperature range so that a high or low-temperature warning is issued if the temperature falls outside of this range.
The LCD display is large enough to read from far away. The screen is also transparent, making this an aesthetically pleasing addition to your aquarium that won’t obscure your view of the inside of your tank.
Capetsma has included the required battery with the purchase of this thermometer so you can start using it straight out of the box.
- Freshwater and saltwater compatible
- Senses water temperature through glass
- Accurate readings to within 0.1°
- Enables high and low-temperature warnings
- Large, transparent LCD display
- Battery included
- Some customer complaints about durability
Neptonion’s Aquarium Thermometer is another digital model that uses an electric probe to measure aquarium temperature.
This thermometer will provide readings in Celsius or Fahrenheit on the digital LCD display, to 1 decimal place and to an accuracy level of 0.1°.
When it comes to operation, this is a very simple thermometer to use, so ensuring the safety of your pets is easy.
Just use the single power button (press and hold) to power on and off. The other switch can then be used to switch between Fahrenheit and Celsius readings.
The probe cable length is roughly 3 feet, leaving you plenty of room to position the thermometer on the outside of your aquarium and still be able to extend the probe into the tank.
2 suction cups are included to adhere the thermometer itself and the probe to the outside of the aquarium.
An LR44 battery is also included for maximum convenience and immediate usage.
- Clear LCD display
- Easy-to-use controls
- 3 ft probe cable length
- Suction cups included for adhesion
- Battery included
- Some reports of inaccuracy due to malfunctioning
SUKRAGRAHA has created something a little different with its Stick-on Aquarium Thermometer.
This thermometer is in the form of a strip that can be stuck to the outside of your aquarium using the adhesive on the back. This adhesive is easily exposed by peeling off the tape on the back of the strip.
Once the thermometer strip is attached to your aquarium, it will read the temperature of the water using a blue, green, and tan color scheme. Degrees are listed up the strip in Celsius and Fahrenheit, and the thermometer indicates the current temperature in green.
A blue color will be used to indicate that the temperature has just surpassed a certain level, and tan indicates that a certain temperature is being approached.
This thermometer comes in a 10-piece set, which is ideal if you have multiple aquariums. It also means that if one thermometer stops working, you always have a spare.
- Color-coded temperature readings
- Easily adhesive
- Affordable option
- 10-piece set
- Colors may not appear as clearly as advertised
Best Aquarium Thermometer
So, as you can see, aquarium thermometers come in many different forms. If you’re still in the process of deciding which type of thermometer will work best for your aquarium, this buyer’s guide will help to point you in the right direction.
Fresh or Saltwater?
The type of water that your aquarium contains has the potential to impact what kind of thermometer you can use.
Luckily, the thermometers on our list are all suitable for both freshwater and saltwater aquariums, so no matter what kind of fish you keep, you can use any of the thermometers listed above to measure their environment’s temperature.
Digital, Analog, or Strip?
Thermometers are much like clocks in the sense that choosing one involves making the decision between a digital or analog display.
As with clocks, a significant part of this decision will be dictated by personal preference, but there are also practical considerations to be made.
Many people find analog thermometers more difficult to read than digital models. Digital thermometers may also be slightly more accurate because they have the ability to provide readings including decimal places.
However, there are also drawbacks to digital thermometers. For one thing, most of them can’t be exposed to water directly, so measurements need to be taken using a probe.
The exception to this, of course, are digital thermometers that use temperature sensors to measure the temperature of the water through the aquarium glass.
Another thing to consider is the fact that digital thermometers require batteries to work, which is not the case with analog models.
Manufacturers may include a battery with the purchase of their thermometers, but the battery will need to be replaced in any case once it runs down.
There is actually a third option: adhesive strip thermometers.
In theory, these are easier to read than traditional analog thermometers and eliminate the probe and battery issues that come with many digital thermometers.
However, in practice, it is thought that these thermometers may be slightly less accurate and are often less easy to read than advertising suggests.
Accuracy is something that we’ve already touched on in the section above, but it’s the single most important factor to consider in an aquarium thermometer.
After all, if the accuracy of your thermometer is compromised, you risk the temperature of your aquarium rising above or falling below the limit and affecting the health of your fish.
Significant temperature deviations can even be fatal, so this needs to be avoided at all costs.
As we mentioned previously, digital thermometers are considered to be the most accurate aquarium thermometers on balance.
This is because, unlike analog and strip thermometers, digital thermometers can provide readings to an accuracy of 1 decimal place, or 0.1°.
In second place when it comes to accuracy is the traditional or analog thermometer.
While this thermometer cannot provide readings to quite the same level of exactitude as digital thermometers (at least, not visibly), they do provide enough accuracy to ensure a safe temperature range for your fish and other aquatic creatures.
The markings provided on analog thermometers usually allow for readings that are accurate to 1°.
Strip thermometers are generally considered to be the least accurate type of aquarium thermometer because they rely on thermal color reactions to provide temperature readings.
Often, these colors do not reveal themselves clearly, or may even fail to appear altogether.
However, this problem can be minimized by using more than 1 strip thermometer to double-check accuracy.
Since strip thermometers usually come in packs of several, this is a relatively easy precaution to take.
The easier your aquarium thermometer is to operate, the easier it will be for you to ensure the health and safety of your fish.
Therefore, ease-of-use is a crucial factor to prioritize when purchasing an aquarium thermometer.
The two main features to consider here are temperature display and settings.
It goes without saying that you’ll want the temperature reading on your thermometer to be easy to read so that you can clearly understand the temperature conditions inside your aquarium.
A large display screen is preferable since the reading will be easier to see from far away.
A transparent screen will also usually be easier to read due to the increased contrast and has the added benefit of not obscuring the inside of your aquarium.
In terms of settings and controls, the fewer buttons the better because too many settings can make the thermometer complicated to use.
Essential controls include a power button (ideally the same one to power on and off) and buttons to switch from Celsius to Fahrenheit.
A useful additional setting is a temperature range function that lets you set the optimal temperature for your tank and gives a warning when this temperature is exceeded or dropped below.
There are various different ways of attaching your aquarium thermometer to your fish tank. Which adhesion or attachment method you choose will come down to what you prefer and what your aquarium will allow.
Some aquarium thermometers do not require any attachment at all. This will only usually be the case with analog thermometers with floating functions that allow them to float freely in the water.
The only real downside to this kind of thermometer is the fact that it can be more difficult to read since it’s moving around.
However, in most cases, floating aquarium thermometers will also come with some kind of attachment feature (usually a suction cup) so that you can still attach it to the glass of the aquarium if you want. This is likely to make the reading process much easier.
Digital thermometers will either use suction cups or adhesive strips to adhere to the surface of an aquarium.
There is no real consensus as to which adhesion method is best and the quality of suction cups and adhesives will vary between manufacturers.
However, non-functional suction cups can often be fixed by cleaning, whereas when an adhesive strip stops working, it will usually need to be replaced altogether.
Strip thermometers, of course, only use adhesive strips for attachment.
Frequently Asked Questions
Do I really need an aquarium thermometer?
The short answer to this question is: yes. Whether you have a basic betta fish aquarium or an extensive saltwater aquarium ecosystem, you need a thermometer. Fish and other aquatic animals are sensitive creatures that require specific environments in order to thrive.
Without a thermometer, you won’t be able to accurately check the temperature of your aquarium. If overly high or low temperatures go unnoticed, your fish may become sick or even die.
What temperature should my aquarium be?
This depends entirely on what kind of aquatic animal or fish you keep in your aquarium since different creatures require different temperature ranges.
For example, tropical fish require warmer water temperatures (usually between 75 and 80°F). Meanwhile, cool water fish, such as goldfish, do better in lower temperatures of 60 to 75°F.
Generally speaking, cool water fish can survive a little more flexibility than tropical fish and are usually able to live in slightly warmer or colder temperatures.
Tropical fish are more sensitive and will become unwell more quickly outside of their ideal temperature range.
Regardless of whether you own tropical or cool water fish, however, it’s safest not to deviate from their optimal temperatures at all.
Other aquatic animals, such as crabs, turtles, and jellyfish, for example, will have other specific temperature requirements that will need to be verified individually.
How do I know if my aquarium thermometer is accurate?
It’s all very well for a manufacturer to advertise their thermometer as accurate, but malfunctions do occur from time to time, so how do you verify whether your thermometer is providing accurate temperature readings?
Well, there are a couple of ways you can go about this. As we briefly mentioned earlier, you have the option of using more than 1 thermometer.
This may not be ideal from a cost or convenience standpoint, but it does mean that you have 2 readings to work with rather than just 1.
This can help you to identify any potential inaccuracies from differences in temperature readings, although further difficulties may then arise when it comes to working out which thermometer is the accurate one (a third thermometer may need to come into play).
Because strip thermometers, for example, usually come in packs, they are a good choice for doubling up.
Another easy method for checking the accuracy of your aquarium thermometer is to use the thermometer against something that you already know the temperature of.
For example, placing your thermometer into or against a glass of ice cubes should yield a reading of 0°C or 32°F. If the reading is off, then you know your thermometer is inaccurate.
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