This might come as a surprise if you are new to aquariums, but keeping fish is not as simple as placing them in the tank and giving them food. There are many other factors that you need to take into consideration, and the water temperature level is the perfect example of that. As you probably know already, fish are coldblooded, and the water temperature needs to stay at a specific level for them to be healthy. Using the right tools to maintain the correct water temperature will be the difference between success and failure. Thanks to this, experts agree that all aquariums should be equipped with a thermometer.
Today we are going to help you find the best aquarium thermometers. We are going to achieve this by taking a look at Amazon’s top 9 bestselling aquarium digital thermometers. We will list their most important features and specifications so that you have an easier time comparing them and finding the one that best fits your needs. Without any further ado, let’s jump right into it.
Cheap & Good | Our Favorite | Customers Choice | |
 |  |  | |
KETOTEK Waterproof Thermometer | VIVOSUN 4-Pack LCD Digital Aquarium Thermometer | Capetsma Digital Aquarium Thermometer | |
Temperature Range | -58°F - +230°F | -58 °F - +158 °F | -32°F - +158°F |
Power | Cable | Battery | Battery |
Color | Black | Black | Black |
Display | LCD | LCD | LCD |
Our Rating | |||
Buying Guide
Considering that your aquarium’s inhabitants are coldblooded and that they rely on the water temperature to keep their bodies warm, you need to make sure to find the best aquarium thermometer. However, this is easier said than done. If you are new to this hobby, then you don’t need to worry because we have your back. Here are the most important specifications and features that you need to look out for:
Simple Installation
Finding a fish tank thermometer that is easy to install is essential. After all, you don’t want to spend thirty minutes trying to figure out what is the best position to mount the device. That’s not all. The more complicated the thermometer is to use, the easier it is to install it wrong, and this will lead to bad temperature readings. The most straightforward thermometers to install are sticky ones such as the LCR Hallcrest A-1005 Liquid Crystal Thermometer that only needs to be placed next to the water level.
Celsius to Fahrenheit Converter
One feature that the best digital aquarium thermometer needs to offer is a Celsius to Fahrenheit converter. If you live in the USA, then you are probably going to prefer having it set in Fahrenheit. The VIVOSUN 4-Pack LCD Digital Aquarium Thermometer is one of the best choices here because it can convert the temperature readings with the single push of a button.
Accuracy and Range
You don’t want to get wrong temperature readings because this can end up hurting the aquarium’s inhabitants. This is why getting a highly accurate device is critical. Generally, a premium product such as the Capetsma Digital Aquarium Thermometer and the KETOTEK Waterproof Thermometer offers readings that are one degree over or under. We also want to mention that some thermometers specialize in being accurate. The HDE Digital Thermostat is an excellent example because it features an accuracy close to 0.1 degree Celsius.
Choose the right Type
If you paid attention to the reviews above, then you probably noticed that there are three types of aquarium thermometers. Let’s go ahead and take a look at their features to see what sets them apart.
Digital
The digital ones are the most popular, and there is a good reason for that. They provide accurate readings and big screens that show all the information that you need to know. On the downside of things, this type of thermometer requires a power source and is quite pricey.
Floating or Standing
Floating or standing thermometers are the ones that need to be fully submerged into the water. They do not use digital screens and, instead, rely on a special liquid that indicates the ideal water temperature level. They have a variety of uses and will stick to your fish tank via suction cups.
Stick-On
The last type is called a stick-on. What makes these thermometers unique is the fact that they are super easy to install and use. The only requirement is to place them close to the water level so that the room temperature does not influence the readings. This type is best suited for smaller fish tanks.
The best Aquarium Thermometers
1st Capetsma Digital Aquarium Thermometer
Specifications
- Dimensions: 2.99 x 0.28 x 2.99 inches
- Weight: 0.2 pounds
- Color: Black
- Display: LCD 3.2″
- Temperature Range: 0°C to 70°C / 32°F to 158°F
- Power: Battery
If you are in the market for a thermometer that features a futuristic design and helps you keep track of the water temperature level at all times, then the Capetsma Digital Aquarium Thermometer is your best choice. The device is equipped with a cordless and touch screen design that helps you avoid having to deal with messy wires and buttons. The screen uses an accurate temperature stick that is fixated on the fish tank to constantly display the temperature reading from 0 to 70 degrees Celsius. Since we are talking about the big screen of the aquarium thermometer, we also want to highlight that it is super easy to operate. With the single touch of a button, you will have instant access to all the vital information.
What’s great about the Capetsma Digital Aquarium Thermometer is that because it uses a temperature stick, it doesn’t need to be placed underwater. You can mount it anywhere you want, and the readings will still be correct. To make things even better, the screen is fully transparent, and this means that it will not ruin the view of the aquarium’s inhabitants. Many factors can impact the water temperature levels, and fortunately, nothing is ever going to take you by surprise if you choose to go for the Capetsma Digital Aquarium Thermometer. The reason why we are saying that is because the device has a special function that alerts you when the temperature is too hot or low.
Pros:
- Futuristic design;
- Touchscreen display;
- The display is transparent;
- Temperature stick (it doesn’t need to be placed underwater);
- It provides accurate readings;
- Temperature warning;
- No messy wires;
- It ships with batteries;
- It is ideal for both fresh and water saltwater tanks.
Cons:
- Changing the readings from Celsius to Fahrenheit is complicated.
2nd VIVOSUN 4-Pack LCD Digital Aquarium Thermometer
Specifications
- Dimensions: 7.8 x 3.8 x 2 inches
- Weight: 0.35 pounds
- Color: Black
- Display: LCD
- Temperature Range: -10℃ to 50℃ / 14 °F to 122 °F
- Power: Battery
Are you looking for a digital aquarium thermometer that is accurate and easy to use? Your search ends here. The VIVOSUN 4-Pack LCD Digital Aquarium Thermometer is an excellent choice for all fish tank sizes, and it features a temperature range of -50 to 70 degrees Celsius. Not just that, but the device guarantees that it is always accurate withing a degree (over or under). With the single press of a button, you can turn the degrees from Celsius to Fahrenheit. The automatic converter is a nice feature to have because it makes it much easier to keep track of the water temperature level.
The VIVOSUN 4-Pack LCD Digital Aquarium Thermometer uses two suction cups for installation. One suction cup needs to be attached close to the probe, while the other one fits next to the thermometer so that you can see the large LCD screen from outside the tank. Since we mentioned the simple installation, we want to note that the VIVOSUN 4-Pack LCD Digital Aquarium Thermometer’s probe can be placed anywhere. The last thing that we want to note about the device is that the manufacturer has bundled it with a super-long cable that measures in at 39.37 inches (1 meter). The great thing about this is that most fish tank thermometers ship with cables that are half the size.
Pros:
- Celsius to Fahrenheit converter;
- Easy installation;
- Strong suction cups;
- The probe can be placed anywhere;
- LCD screen;
- Super-long cable;
- It offers accurate readings withing a degree (over or under).
Cons:
- Reviews show that the display can have issues.
3rd KETOTEK Waterproof Thermometer
Specifications
- Dimensions: 1.85 x 1.1 x 0.67 inches
- Weight: 0.1 pounds
- Color: Black
- Display: LCD
- Temperature Range: -50℃ to 82℃ / -58°F to 180°F
- Power: USB
The problem with most thermometers is that they are sometimes a bit too big for smaller aquariums. This leads to the device taking up quite a big part of the view, and this is never good. Fortunately, here is where the compact KETOTEK Waterproof Thermometer comes in and provides an alternative. This is a high-performance waterproof thermometer that uses a USB power supply and accurate readings. The device is equipped with a stainless waterproof NTC probe that features excellent sensitivity and accuracy to provide you with the best temperature readings. In addition, the temperature range is -50 to 70 degrees Celsius (it can be converted to Fahrenheit).
The KETOTEK Waterproof Thermometer uses an LCD screen that is paired with a bright backlit panel to make it easier to see the water temperature level. As previously noted, the device uses a USB power supply. This is great news for aquarium hobbyists because it makes it possible to fuel the thermometer from any device that has a USB port; this includes smartphones, tablets, and laptops. Another essential feature is worth a mention is that the manufacturer inspects all devices before shipping to make sure that they are working flawlessly. This is why KETOTEK is offering a 12-month warranty for every digital fish tank thermometer that it sells. Due to this, you will not have to worry about buying a new aquarium digital thermometer anytime too soon.
Pros:
- 12-month warranty;
- Accurate readings within half a degree (over or under);
- It uses a USB power supply;
- Stainless waterproof NTC probe;
- Large LCD screen with backlit panel;
- Celsius to Fahrenheit converter;
- It provides 2×40” cords.
Cons:
- The Celsius to Fahrenheit converter button is tricky to use.
4th HDE Digital Thermostat
Specifications
- Dimensions: 4 x 4 x 0.5 inches
- Weight: 0.4 pounds
- Color: Black
- Display: LCD
- Temperature Range: -23℃ to 60℃ / -10°F to 140°F
- Power: Battery
The HDE Digital Thermostat ships with a small design, and a large display that allows for easy reading of the temperature. The LCD screen uses a strong suction cup, and it can be placed anywhere on the aquarium, while the probe needs to be submerged into water to make the readings as accurate as possible. In fact, the manufacturer claims that the readings are as precise as within 0.1 degrees Celsius. It doesn’t get closer than this! The HDE Digital Thermostat doesn’t need a power supply because it runs on batteries, and you will be getting two LR44 batteries in the package. Since the device uses little power, the batteries will last for months.
As it is the case with all premium fish tank thermometers, the HDE Digital Thermostat offers a temperature range between -50 to 70 degrees Celsius. The readings can be easily converted to Fahrenheit. On the downside of things, the compact design of the thermometer and the probe means that it will not perform very well in large tanks such as 80-gallons, for example. We want to highlight that the product is sold in a bundle of two. Therefore, you will be getting two digital aquarium thermometers for the price of one!
Pros:
- Accurate readings within 0.1 degree Celsius;
- Ideal for smaller tanks;
- The digital thermometer ships in a package of two (you are getting a free one);
- It includes 2x LR44 batteries (long-lasting);
- Temperature range between -50 to 70 degrees Celsius;
- Celsius to Fahrenheit converter;
- Strong suction cups;
- LCD screen.
Cons:
- The build quality is not very durable.
5th Zacro LCD Digital Aquarium Thermometer
Specifications
- Dimensions: 7.1 x 4.3 x 2 inches
- Weight: 0.13 pounds
- Color: Black
- Display: LCD
- Temperature Range: -10℃ to 50℃ / 14°F to 122°F
- Power: Battery
Did you just finish setting up your aquarium, and you are running on a tight budget? If that is the case, then the Zacro LCD Digital Aquarium Thermometer might be your best choice. The first thing that we want to mention about this device is that it ships in a pack of two. Yes, you read that right. By buying this digital thermometer for aquariums, you are getting a free one. The devices use LCD screens to display water temperature levels with an accuracy of 2 degrees Celsius (over or under). The compact design of the devices is also a great feature because it means that you will not have any trouble finding a good spot to place them, as long as the probe is fully submerged.
Installing the Zacro LCD Digital Aquarium Thermometer is super simple. The only thing you need to do is to secure the suction cups, and you are good to go. You don’t even have to buy a new set of batteries because the manufacturer has included two LR44 batteries for free. What makes the Zacro LCD Digital Aquarium Thermometer special outside of its affordable price tag is the fact that it has a wide range of applications. You can use it to monitor the temperature of freshwater, saltwater, and marine water tanks without a single problem.
Pros:
- The digital thermometer ships in a package of two (you are getting a free one);
- LCD screen;
- Strong suction cups;
- Temperature range between -50 to 70 degrees Celsius;
- It includes 2x LR44 batteries;
- Easy to install;
- Celsius to Fahrenheit converter.
Cons:
- The temperature readings have an accuracy of 2 degrees Celsius (over or under).
6th Fischuel LCD Thermometer
Specifications
- Dimensions: 6.8 x 5.2 x 1.5 inches
- Weight: 0.1 pounds
- Color: Blue
- Display: LCD
- Temperature Range: -20℃ to 70℃ / -68°F to 158°F
- Power: Battery
On the sixth spot, we have another budget-friendly device that provides accurate readings. The Fischuel LCD Thermometer is a great choice for smaller tanks, and it stands out from all the other devices featured on our list with its extremely easy to use design. The device doesn’t have any buttons, and the only thing you need to do is use the suction cup to secure it tightly. Talking about the positioning of the digital thermometer, we want to mention that it can go both outside and inside the tank. The manufacturer has equipped it with an all-sealed body that ensures full protection from water.
If you don’t want to deal with messy wires, then you are going to love the Fischuel LCD Thermometer that works without external cables or probes. Despite not using a probe, the device features a wide temperature range of -20 to 70 degrees Celsius, which is more than enough for a regular fish tank. The power comes from LR44 batteries, and the manufacturer included a pair of extra batteries in the bundle for free. That’s not all. The Fischuel LCD Thermometer is built to last, and therefore, it shouldn’t come as a surprise to find out that the manufacturer is offering a 12-months warranty.
Pros:
- Modern design;
- Fully waterproof;
- It can be placed both outside and inside the fish tank;
- It includes extra LR44 batteries;
- 12-month warranty;
- Wireless;
- Resilient to room temperature changes.
Cons:
- The accuracy is sometimes off by up to 5 degrees.
7th LCR Hallcrest A-1005 Liquid Crystal Thermometer
Specifications
- Dimensions: 4 x 0.5 x 7 inches
- Weight: 0.02 pounds
- Color: Black
- Display: Liquid Display
- Temperature Range: 18℃ to 29℃ / 66°F to 84°F
- Power: no Power needed
Not all aquarium thermometers are digital and rely on batteries or power plugs to run. There are also strip thermometers that sell for affordable price tags and are accurate. The LCR Hallcrest A-1005 Liquid Crystal Thermometer is the perfect example shipping with a sticky peel that allows you to mount it vertically outside of your fish tank, just below the waterline. As the product’s name implies, it uses liquid crystals that are color changing. The color scheme is super useful because it allows you to see if the water temperature level is off just with a simple glance.
The LCR Hallcrest A-1005 Liquid Crystal Thermometer is equipped with a numerical display that is easy to read and accurate. In case you don’t stick the thermometer just the way you want it from the first try, then you don’t need to worry because the LCR Hallcrest A-1005 Liquid Crystal Thermometer can be removed and re-positioned. Out of all the strip thermometers available on Amazon, we think that the LCR Hallcrest A-1005 Liquid Crystal Thermometer is the best one that you can get thanks to its color changing technology.
Pros:
- Easy to read;
- Color changing technology;
- Super easy to install;
- It can be repositioned;
- It is ideal for smaller tanks;
- Wireless;
- It doesn’t require batteries;
- Affordable price.
Cons:
- It is not as accurate as digital thermometers.
8th American Thermal Aquarium Thermometer
Specifications
- Dimensions: 0.75 x 2 x 0.7 inches
- Weight: 0.02 pounds
- Color: Black
- Display: Liquid Display
- Temperature Range: 20℃ to 28℃ / 68°F to 82°F
- Power: no Power needed
The American Thermal Aquarium Thermometer has stellar reviews that show it sticks properly to both acrylic and glass aquariums. While you don’t have to worry about it peeling off, this is not the most significant benefit using the strip thermometer. The best thing about this fish tank thermometer is the fact that it delivers super-accurate readings and a wide range of water temperatures. Just like the previous product on our list, the American Thermal Aquarium Thermometer uses color changing technology to make the temperature readings easier to spot. The liquid crystal is sensitive to temperature, and it quickly changes colors when it spikes or drops.
The design of the American Thermal Aquarium Thermometer is as straightforward as they come. You just have to peel and stick the thermometer on the tank. However, you should make sure to place it below the waterline to get the most accurate readings possible. To make things even better, the thermometer can be replaced, and it will not lose any of the stickiness in the process. Another significant benefit that we want to mention is that the American Thermal Aquarium Thermometer is unbreakable, non-corrosive, and non-toxic.
Pros:
- Easy to read;
- It can be repositioned without losing stickiness;
- Unbreakable design;
- Non-corrosive and non-toxic;
- Accurate readings;
- Wireless;
- It doesn’t require batteries;
- Color changing technology.
Cons:
- It doesn’t work that well with bigger fish tanks.
9th Marina Floating Thermometer with Suction Cup
Specifications
- Dimensions: 7 x 4 x 1 inches
- Weight: 0.02 pounds
- Color: White
- Display: Liquid Display
- Temperature Range: 0℃ to 50℃ / 32°F to 122°F
- Power: no Power needed
Do you need a more traditional aquarium thermometer? If yes, then your search ends here. The Marina Floating Thermometer with Suction Cup is an easy to use device that features a liquid pool to indicate the water temperature level. Not just that, but it is also equipped with green space indicators that show you what is the ideal temperature for your fish to thrive. This might seem like an insignificant feature, but it’s quite useful because it allows you to see if the temperature is correct with a single glance.
The thermometer is designed for saltwater use, but it isn’t limited to that. The Marina Floating Thermometer with Suction Cup can be used on all types of fish tanks, and thanks to the strong suction cups, you can install it on the side of the tank. This means that you can move the thermometer without having to worry that it will fall out of the suction cup holder. Using the Marina Floating Thermometer with Suction Cup will give you peace of mind that the aquarium is at the right temperature and that your fish are happy.
Pros:
- Traditional design;
- It uses strong suction cups;
- Great for both fresh and saltwater tanks;
- It features a green zone for the ideal temperature;
- Easy to use;
- More than 5,000 stellar reviews.
Cons:
- The suction cups may cause damage to acrylic tanks.
Frequently Asked Questions
What is the best Thermometer for an Aquarium?
This depends on the type of aquarium that you have set up in your home. If we had to pick one of the products that we reviewed today as the best, then the Capetsma Digital Aquarium Thermometer that ships with a transparent display and accurate readings is our choice. On the other hand, a cheaper product as the American Thermal Aquarium Thermometer will still get the job done.
How does an Aquarium Thermometer work?
Aquarium thermometers measure the water temperature level, which is different than regular thermometers that measure the air above the water and ambient temperature. In addition, some thermometers are equipped with probes that need to be fully submerged into the water to get the most accurate readings possible.
Where is the best Place to put a Thermometer in a Fish Tank?
If the thermometer you purchased has a probe, then you can place it anywhere you want, and the readings will still be accurate. However, some devices use digital sensors and stick-on meters. The best spot to put them is right at the top of the water level so that the room temperature doesn’t mess with the indicator.
How do I read an Aquarium Thermometer?
Digital aquarium thermometers are super easy to read. All the information that you need to know is displayed on an LCD screen. Not just that, but the degrees can be converted from Celsius to Fahrenheit with the simple press of a button. On the other hand, there are stick-on thermometers that feature a sticky strip and mercury. The mercury will go up or down (depending on the temperature), and you can see the actual temperature level by reading the degree that is closest to the line’s top.
What Temperature should my Aquarium Water be?
Finding the ideal water temperature is ideal if you want your fish to be healthy and happy. The tricky part here is that not all species thrive at the same temperature. Take, for example, goldfish that require a range between 65 to 68 Fahrenheit degrees while fancy tail goldfish need a range of 65 to 72 degrees Fahrenheit. Therefore, you first need to find out what is the temperature that your species likes.
