10 Best Aquarium Thermometers: Reviews | Aquascape Addiction

10 Best Aquarium Thermometers: Reviews

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Our reviews of the 10 best aquarium thermometers, we cover each in detail as well the benefits of using a thermometer in your fish tank.

10 Best Aquarium Thermometers: Reviews

We are here today to talk about everything to do with aquarium thermometers and which ones are the best possible options for you to go with for your fish tank.

The water temperature in your aquarium is an extremely important thing to monitor in order to keep your fish alive and healthy.

Some fish need warmer water and some need colder water, with the best way to keeping track of it being an aquarium thermometer. so it's important to get your hands on the best aquarium thermometer you can. This our top pick and what we personally use.

General Tools Thermometer 9.7/10
Zacro LCD Digital Thermometer 9.5/10
Fluval Wireless Digital Thermometer 9.4/10
Fluval EDGE Digital Thermometer 8.7/10

What Is A Aquarium Thermometer & What Does It Do?

We assume that everyone knows what a thermometer is. Well, an aquarium thermometer is one which measures the temperature of the water in your aquarium. Some may also come with a feature that alerts you when the temperature falls below or rises above a certain point.

Fish need water that is of a specific temperature, and these are tools which allow you to keep your fish happy and healthy by keeping track of water temperature.

A protein skimmer is also a good piece of kit to consider for keeping your aquarium nice and clean.

What Makes A Good Aquarium Thermometer?

These things are pretty basic so there are just a few things that you need to look out for before you make your purchase. One of the most important things to consider is what the temperature range of the thermometer in question is.

It should be able to go at least as low as 10 degrees Celsius and up to 40 degrees Celsius. If you are looking for a heater then check out our aquarium heater buying guide here, we reviewed 9 of the best options.

Another thing that you definitely need to pay attention to with any aquarium thermometer is the accuracy level which it has. The thermometer you get should always be accurate to within at least +/- 1 degree Celsius, and the more accurate it is, the better. On that same note, ideally an aquarium thermometer should display the temperature in both Celsius and Fahrenheit.

A good aquarium thermometer should either be able to be fully submerged in the water, or should have a probe attached to a cable and an LCD display for easy reading.

Moreover, a good aquarium thermometer does not have to be digital or electronic because mercury thermometers or color changing crystal thermometers work fine too.

Benefits Of Using A Thermometer

Like we mentioned before, most fish need a very specific water temperature to stay alive, therefore being able to monitor the water temperature is crucial to the health and happiness of your fish.

Having a thermometer to measure the water temperature in your aquarium will let you heat or cool down the water in your fish tank as your fish need. These things remove the need to guess at the water temperature in your fish tank.

Best Aquarium Thermometer: Our Pick

Here is a summary of our top pick that we personally feel is the better option out of the 10 we have reviewed;

General In and Out Aquarium Thermometer

The General In and Out Aquarium Thermometer is a really nice choice to go with and our top pick (you can check the current price here). It has the ability to measure temperatures as low as -58 to 158 degrees Fahrenheit, or -50 to 70 degrees Celsius. It can be used to easily measure the temperature in both freshwater and saltwater aquariums, so you don’t have to worry about rusting or corrosion.

To make like easier for you, this aquarium thermometer has both a minimum and maximum memory. It also features a high and low temperature alarm which you can set yourself to the temperatures you require an alert for.

This helps you maintain a steady temperature in the aquarium to keep the inhabitants alive and healthy. The General Aquarium Thermometer features an industrial design which is extremely durable and long lasting.

It comes with a nifty foldaway stand so you don’t always have to hold it, plus it has backlighting for those dark times too. The jumbo aquarium digital thermometer display makes this thermometer easy to read and operate at all times.

It actually allows you to change back and forth between ambient and remote sensing. It also comes with a suction cup so you can mount the sensor on the inside of the aquarium with ease.


  • Comes with a stand and suction cup.
  • Wide range of measurable temperature.
  • Lets you switch from F to C.
  • Works for salt and freshwater.
  • High and low temp alerts.
  • Max and min memory function.
  • Backlit for easy reading.
  • Ambient and remote sensing.


  • Temperature readings may become inaccurate after prolonged use.

See more info and pricing at Amazon

9 Other Great Options To Consider

When it comes to great aquarium thermometers we would of course recommend the above option, but if you don’t see it the same way we always have 9 other options which might suit your needs and likes a little more, so here they are.

1. Lifegard Aquatics Digital Temp Alert

One of the really neat parts about this particular thermometer is that it has the ability to measure both room temperature and the temperature of the water inside of an aquarium.

It uses a normal measuring tool to gauge air temperature while also featuring a submersible probe to measure water temperature. The display features a simply to mount suction cup that you can just stick onto the side of any aquarium. This is in our opinion one of the best digital aquarium thermometers out of our picks.

This is great because you can actually use it to monitor the temperature in terrariums too. The Lifegard Aquatics Digital Thermometer features a high and low temperature alert for the probe and a high and low temperature alert for the room as well.

It’s a very accurate and easy to use thermometer with an easy to read digital display. This one is ideal for both saltwater and freshwater applications.


  • Dual temperature readings – air and water.
  • Easy to mount with suction cup.
  • Nice LCD display – easy to read.
  • Works for saltwater and freshwater applications.
  • Various kinds of alerts.
  • Wide temperature range.


  • Fairly wide margin of error.

See more info and pricing at Amazon

2. Zacro LCD Digital Aquarium Thermometer Fish Tank Water Terrarium Temperature

The Zacro LCD is definitely one of the better options out there to go with, and it’s thanks to the convenient nature of it, its durability, and its ease of use.


One of the things that we really like about this particular aquarium thermometer is that it is powered by one single LR44 button cell battery which lasts a very long time, plus it can be easily replaced as well for continued use.

Another thing that is very beneficial about the Zacro Aquarium Thermometer is that it has a massive temperature range. This thing can measure temperatures anywhere between -50 degrees Celsius and +70 degrees Celsius, making it one of the most versatile thermometers out there.

There is also the fact that this model of aquarium thermometer is extremely accurate and it can measure temperature to within +/- 0.1 degrees, this being very accurate.

Moreover this thermometer has a large easy to read LCD display so you don’t need a magnifying glass when trying to read the temperature. Even though the screen is fairly large, the whole thermometer is actually pretty small, making it very portable and easy to store in small spaces.

This thing is also convenient because it comes with a suction cup so you can stick the thermometer on the outside of your fish tank, while keeping the temperature probe submerged on the inside of the tank for continuous temperature readings.

If you want a durable and accurate aquarium thermometer, this thing definitely makes for a prime choice even as a marine tank thermometer.


  • Suction cup to hang it on the side.
  • Probe can be submerged for easy use.
  • Small and compact nature.
  • Large easy to read LCD display.
  • Powered by a simple to replace button cell battery.
  • Wide temperature range with accurate readings.


  • Battery connection may be a little loose.

See more info and pricing at Amazon

3. Pet Magasin Digital Thermometer

This is a very unique but useful digital fish tank thermometer choice to go with. The Pet Magasin Digital Thermometer is actually also a hygrometer, which means that it can read humidity levels in the air.

This is one of the reasons why we really like this model, because it can be used for terrariums and turtle habitats to measure the level of moisture in the air.

Of course, at the same time, it also works really well for measuring the water temperature of aquariums. What is really cool about this model is that you can stick the Pet Magasin on the outside of the aquarium glass and it will use special digital reading techniques to measure the water temperature on the inside.

To attach it, simply remove the protective cover and stick it on anywhere. It uses a special type of glue to stick on, one that does not leave stains or residue, and can be even be re-stuck in a different location.

The Pet Magasin Thermometer comes with a convenient LCD display that is large and easy to read, plus it can switch between C and F to suit your preferences.

It may not be fully submersible in water, but it does have a tough outer shell and can handle getting misted or sprinkled with water for a prolonged period of time.


  • Accurate readings of humidity.
  • Good for humidity and temperature readings.
  • Tough and water resistant.
  • Can give readouts in F and C.
  • Easy to read digital display.
  • Easy to mount on the outside of aquariums and terrariums.


  • Battery life is not great.
  • Works better for humidity than water temperature.
  • Not fully submersible.

See more info and pricing at Amazon

4. KollerCraft TOM Temp Alert Digital Thermometer

This is a fairly advanced aquarium temperature reading device that is fairly durable, very accurate, and will definitely help you keep the temperature in your aquarium at the level which you want it at. It is a special thermometer meant to alert you of changing water temperatures so you can keep your fish alive.


One of the coolest features of the KollerCraft Digital Thermometer is that it features audible and LED notifications which can alert you of the water temperature.

You can set a minimum and maximum temperature at which the water should be at, and when the water temperature falls below or rises above that preset level it will alert you so you can make changes accordingly.

Another thing that is pretty neat about this this is that it is corrosion proof, making it ideal for both fresh water and salt water aquariums.

It is also a really good option because it comes with suction cups so you can stick the thermometer on the outside of the fish tank or even on a wall beside the aquarium.

The KollerCraft also has a 3 foot long cord which makes it more than convenient to place in any way which you see fit. This is a very accurate thermometer that can read temperature very well without question. Overall this is a good thermometer with alert features for fish safety, plus it is convenient and easy to use as well.


  • 3 foot long cord with temperature probe.
  • Preset alerts to tell you of rising or falling temperatures.
  • Ideal for salt water and fresh water aquariums.
  • Audible and LED notifications.
  • Suction cups for easy mounting.


  • Temperature may be off by as much as 2 – 3 degrees Fahrenheit.

See more info and pricing at Amazon

5. Fluval EDGE Digital Aquarium Thermometer

This is actually one of our favorite thermometers out there right now for aquariums. The reason for this is because it does not require the use of any batteries. The Fluval Edge Digital Aquarium Thermometer uses a special gel-like substance which reacts with temperatures and switches colors based on the temperature.

Not needing any batteries is a big advantage when it comes to years and years of measuring water temperature.

This Fluval Thermometer is accurate to within roughly 2 degrees Celsius, which is not too great, but on the other hand, the gel substance never loses its efficacy. In other words, the Fluval Edge Thermometer never loses accuracy over the years.

The temperature range on this particular aquarium thermometer is between 64 and 86 degrees Fahrenheit, which is more than good enough for most aquariums.

Even better is that this can be used for both freshwater and saltwater applications. We also like this model because it is very easy to mount on the outside of any aquarium.

It uses a special adhesive that simply sticks to the tank, plus it can even be removed and reattached a couple times in other locations before the adhesive wears off.


  • Easily mounted.
  • Works for salt and freshwater.
  • Gel substance does not lose accuracy.
  • No batteries required.
  • Ideal for most aquariums.


  • Only accurate to within 2 or 3 degrees.
  • Fairly narrow temperature range.

See more info and pricing at Amazon

6. Fluval Submersible Digital Thermometer

The Fluval Submersible Digital Thermometer is really easy to use thanks to the fact that you can just stick it on the inside of your aquarium with the included suction cup mount and let it do its job.

This Digital Thermometer comes with a very large and easy to read LCD display. This makes seeing the temperature reading easy even with the distortions caused by water and glass aquariums. It is sealed in a very tough and durable plastic shell to protect all of the internal components.

This is a fully submersible thermometer, so the manufacturer’s definitely made sure that it won’t leak and damage the electronics on the inside. The Fluval Submersible Thermometer is ideal for both saltwater and freshwater aquariums.

It won’t corrode, rust, or deteriorate in saltwater. This model may not have any special features, but it does a great job at reading the water temperature in any aquarium.


  • Very accurate.
  • Can read in C and F.
  • Easy suction cup mount.
  • Fully submersible.
  • Rugged and totally waterproof outer shell.
  • Good for freshwater and saltwater applications.


  • No high or low temperature alarm.
  • No memory.

See more info and pricing at Amazon

7. Marina Floating Thermometer with Suction Cup

If you need a simple to use thermometer that can simply float in the water and has accurate readings, the Marina Floating Thermometer is definitely a good choice to go with.


This is perhaps one of the easiest and simplest to use aquarium thermometers that you could go with. While it does not use a probe and does not have an LCD display, it does use the time tested method of using mercury to measure temperature.

This fact alone makes it an extremely accurate thermometer that will never be off point in terms of the reading it gives you.

This thing is very simple to use in the sense that all you have to do is place it in the water.

It is a floating thermometer that you simply place in your aquarium to get accurate temperature readings. Even better is that it comes with a suction cup so you can stick it onto the inside of your aquarium wall so it will stay in place.

For your convenience the Marina Floating Thermometer displays the temperature in both Celsius and Fahrenheit, plus it even has safety zone indicators so you can tell when the water is too cold or far too hot for your fish.

This is a very simple to use basic thermometer that does not require any batteries and gives you an accurate reading 100 percent of the time.


  • Does not need batteries.
  • Simply let it float in your aquarium.
  • Suction cups to attach it to the side of your fish tank.
  • Gives you accurate readings 100 percent of the time.
  • Easy to mount and easy to read.
  • Displays temperature in both Celsius and Fahrenheit.


  • Temperature reading is somewhat small.
  • Suction cups may leave marks on the inside of your fish tank.

See more info and pricing at Amazon

8). JCreate Digital Touch Screen Thermometer

This is definitely a cool option to go with, which for one is because you don’t need any probes or wires for it. This thing can be stuck to the outside of an aquarium and that’s that. It can read the water temperature simply by being on the exterior of the aquarium.

Moreover, besides the numbering, most of it is transparent too, so it’s not too much of an eyesore. The JCreate Digital Touch Screen Thermometer does require simple disposable batteries, which can easily be inserted, and the battery life isn’t too bad either.

This aquarium thermometer can display in both Fahrenheit and Celsius, so you can use whichever unit of measurement works best for you.

What is also a benefit here is that this thermometer is very accurate, to within a fraction of a degree. The JCreate Digital Touch Screen Thermometer comes with a 12 year warrant in case anything goes wrong with it.


  • Simple to operate.
  • Very accurate.
  • Looks decent.
  • No probes or wires.
  • Good warranty.


  • Not the most durable.

See more info and pricing at Amazon

9). Marina Stainless Steel Thermometer

Here we have a super simple option to go with, and it looks almost like one of those old school mercury thermometers which people used to have back in the day. Simply hook it onto your aquarium, the interior of it, and it’s good to go.

Keep in mind that instead of mercury, this thing uses alcohol, which contracts and expands depending on the temperature, and yes, the Marina Stainless Steel Thermometer provides both Fahrenheit and Celsius readouts, plus it’s about as accurate as possible.

We do like how it is made out of stainless steel, because it is very durable. However, that said, it’s definitely not the most attractive or good looking option out there.

However, it’s simple, basic, accurate, and durable too.


  • Very accurate.
  • Super durable.
  • Easy to use.
  • F & C.


  • Doesn’t look very nice.

See more info and pricing at Amazon

Commonly Asked Questions

Do I need a thermometer for my fish tank?

Yes, in pretty much all cases, getting an aquarium thermometer is a good idea, or more than a good idea, a necessity really. Fish need a certain water temperature to stay healthy, happy, and alive.

Without a half decent thermometer, you won’t know how warm or cold the water is, and that’s a problem.

Should I get a wireless aquarium thermometer?

This is really up to you, and it’s more a matter of personal preference and aesthetics than anything else.

So, a wireless aquarium thermometer is going to look better than those with wires, simply because there aren’t wires to deal with. There is also the fact that you don’t have to have an external power source.

On the other hand, with wireless thermometers also comes with problem of batteries. Replacing batteries and monitoring battery life can be a real pain in the neck.

Are aquarium strip thermometers accurate?

Aquarium strip thermometers are accurate enough for what they are. Yeah, they don’t cost much and are easy to use, but not the most accurate in the world.

Yes, they will give you a rough readout, or even a rough estimate of the water temperature, but they can definitely be off by a few degrees.

So, if you have really sensitive fish in your tank that need a very specific water temperature, then you will want to avoid strip thermometers.

Can fish die if the water is too cold?

Yes, water that is too cold will cause the metabolism of fish to slow down to a rate that is beyond acceptable, it can cause behaviour issues, and it will cause internal organs to shut down. Simply put, fish will freeze if the water is too cold.

Can fish die if the water is too warm?

Just like if the water is too cold, yes, fish can also die if the water is too warm. Here, their metabolism ramps up way past the point of acceptability and internal organs will also lose function.

Instead of freezing, fish get too hot in water that is too warm, and in more ways than one, this can lead to death.

How To Read A Fish Tank Thermometer

Ok, so this is going to be fairly short and sweet. Simply put, not to sound childish or condescending, but the way to read an aquarium thermometer is with your eyes and common sense.

Most aquarium thermometers are simple tools with a probe that you can stick in the water, with many resting permanently in the water.

The thermometer will have a display on it which shows you the temperature, usually in numbers. If the display says that the water is at 75 degrees, well the way to interpret this is at face value.

Unless the thermometer is broken or not accurate, you read an aquarium thermometer by looking at the numbers displayed. If you have a good digital aquarium thermometer, it should be accurate.

Yes, there are some thermometers with expanding liquids, not much unlike old school mercury thermometers. They also have numbers to tell you where the temperature is at.

There are even some strips that feature chemical reactions. The key is really looking through some good aquarium thermometer reviews to find the right option, we have covered many of what we consider to be the better options already on this article.

They will change to a certain color based on the temperature of the water. Use the instructions and the color code to determine which color represents which temperature range.

These tend to be fairly accurate, but they are also quite vague. Dark blue might mean that the water is between 74 and 78 degrees, just for example. It’s of course a good idea to get the most accurate aquarium thermometer that you can get your hands on so you can be sure the readings are spot on.


An aquarium thermometer is a really useful tool to have if you are an aquarium owner. We would obviously recommend one of the above options (this one is our top pick), all of which are fairly accurate in terms of reading water temperature in your tank, something which is vital for keeping your fish alive.