Picking the best aquarium heater for your tank is essential if you want your fish to thrive.

It’s really as simple as that.

Fish rely solely on the heat of the water around them to maintain their own body temperature. This means if your aquarium heater doesn’t do its job, it could be unsafe for the critters that live inside.

But it can be a lot of work to find out what the best aquarium heaters are, and which is right for your tank setup.

That’s why we’ve gone ahead and done the hard work for you.

Each of the fish tank heaters on our list has been put through our meticulous research and grading process and come out the other side unscathed.

Without further delay, let’s begin:

Why Your Fish Require A Top-Notch Heater

As we hinted to above, the importance of finding a good fish tank heater cannot be overstated.

Here are a few major reasons why:

The entire goal of your aquarium should be to mimic the ecosystem your fish are used to living in when it comes to water conditions. Everything needs to be stable and safe.

If your aquarium heater does a poor job of regulating the water temperature, this can cause serious health problems for your fish (sometimes even resulting in death).

This is why “good enough” heaters should never be considered in our opinion. Even if they work 95% of the time, one instance of wildly fluctuating water temperature can be enough to devastate the life inside your tank.

You need to demand perfection and reliability from the aquarium heater you choose.

The Different Kinds Of Aquarium Heaters

Before we dig into the aquarium heater review guide, we figured it would be smart to list out the different kinds of heaters that are on the market.

If you’re a bit more experienced and already know what kind of heater you need, you can skip this section. If not, we recommend giving this a glance.

Submersible Aquarium Heaters

We wanted to start with submersible aquarium heaters because they are one of the most commonly used types out there. A few of the heaters in our review list below are submersible as well, so it’s important that everyone understands what they are.

In short, a submersible fish tank heater works by being placed inside the tank and under the surface of the water. Once there, it can warm the water very efficiently.

In fact, it’s one of our favorite kinds.

The reason for this is submersible aquarium heaters are master of consistency. By being directly in the water (compared to other heaters) they are able to monitor and impact the water temperature quite easily.

They’re also a breeze to set up as well. This combination of high-performance with a user-friendly setup is why they’re so popular right now (and likely will be for a long time).

Immersible Heaters

Hanging heaters are another name for immersible fish tank heaters, and you’ll see both phrases get used interchangeably.

As you may have guessed, an immersible heater is mounted and hangs above the water in your tank. It applies heat from the top-down as a way of warming up the water.

There are some pros and cons to immersible heaters.

Pros:

  • They’re affordable
  • Often come included with beginner tank kits

Cons:

  • It can make moving the hood/lid of your tank more difficult if you need to open it up
  • It doesn’t provide the same consistent and effective heating that submersible heaters do

There are definitely immersible aquarium heaters that do the job, and we’re not knocking all of them. It’s just worth noting that at some point you’ll likely be upgrading to a different kind of heater.

In-line Aquarium Heaters

This is kind of fish tank heater operates a little differently than the first two on our list. Instead of working to warm the water that sits directly in the tank, an in-line heater works its magic down the chain.

What does that mean?

Simply put, an in-line heater is placed either in the sump or before the filter. When water passes through this area, it gets warmed by the in-line heater.

The advantage of this is that you can keep your tank tidy, clean, and free of additional equipment.

This is great for aesthetics, but also functionality. Certain fish and aquatic life can be aggravated by odd objects in their tank.

By keeping your aquarium heater out of sight, you’ll keep them happy and stress-free.

The major downside of in-line heaters is the cost. We typically don’t recommend them unless you think another kind of heater will bother your fish.

Substrate Heaters

You won’t see many of these around anymore, but they’re worth including on the list because they used to be quite popular. Because of this, there are still a decent number of them floating around.

Substrate fish tank heaters operate by heating the water from the bottom up. Wires are mounted onto the base of your tank where they radiate heat throughout the water.

As you might have guessed by the whole “mounting wires onto your tank” thing, these can get a little pricey.

When you compare that to the ease of simply dropping a submersible heater into the water, it’s pretty obvious why the aquarium community has moved away from these.

Our Reviews Of The Best Aquarium Heaters

Since aquarium heaters are such an important piece of equipment, we needed to do a lot of research to make sure we were happy with our choices.

By the time we finished, we had taken our initial list of over 40 heaters and whittled it down to six.

Here’s how:

  • We used bad reviews, weird specs, and unreputable companies to quickly trim the list down initially.
  • Then we got into the weeds and looked at the details of the remaining heaters on our list (price, specs, etc.)
  • Lastly, we sourced feedback from the fishkeeping community and got our hands on these heaters whenever possible.

This process gave us our list of the best aquarium heaters you see below. We’ve gotten great feedback on it so far and we know you’ll find it helpful.

1. Cobalt Aquatics Flat Neo-Therm Heater

Kicking things off is the Neo-Therm Heater from Cobalt Aquatics. Cobalt is known for making great products, and that definitely holds true with this heater.

This is a submersible heater that looks fantastic and performs very well. It has a temperature range of 66°F to 96°F which gives you a lot of options for the kind of fish it’s compatible with. The wattage range is 25W to 300W depending on which model you choose.

The design is sleek and flat. This means it won’t take up much space in your tank or draw your eye away from the rest of the tank. However, when you do look at the heater it won’t be an eyesore. This is great for the aquarist crowd that takes the aesthetics of their tank very seriously. 

One of the things we love about this aquarium heater is the safety and reliability you get when you buy it. Cobalt offers a 3-year warranty and they won’t fight you on it if you have a problem (which you likely won’t).

This submersible aquarium heater is made with a shatterproof outer casing that pretty much guarantees this thing will stay intact. It also comes with some pretty advanced internal safeguards that will stop it from overheating, and a reliable auto shut off feature.

It also has a clear LED display that makes it easy to see the temperature of your tank and the temp that your heater is set to.

Pros:

  • Extremely reliable
  • Comes with a 3-year warranty
  • Shatterproof outer casing
  • Looks great
  • The LED display is easy to read
  • Tons of great feedback online

Cons:

  • A little on the pricey side
  • There have been reported issues with the included suction cups

2. The Fluval E Electronic Heater

This heater is a very popular option in the fishkeeping community for a number of reasons.

It features a nifty design that looks great in pretty much any tank and it’s a very affordable buy. It’s also pretty compact which means as a submersible aquarium heater, it can be tucked out of the way with ease.

There are three wattage options for this heater: 100W, 200W, and 300W. Easy to remember!

The Fluval E Electronic Heater also heats the water surprisingly quickly. This was something that we didn’t expect given the compact nature of the device. It has a range of 68°F to 93°F.

It also comes with a well-made LCD display that will show you the temperature and make it clear if the water temp isn’t where it needs to be.

Fluval offers a 5-year warranty on this product as well, which we think is fantastic. Compared to some of the other fish tank heaters out there, this is priced very reasonably. 5 years is a long amount of time!

There’s also an effective fish guard that will stop any fish or invertebrates from crawling into contact with this submersible heater.

Installation is simple too. It comes with a side mounting glass adapter in case you can’t mount it on the rear wall of your tank. Overall you should be able to have this heater up and running in 30 minutes if you follow the instructions.

Pros:

  • Reasonably priced
  • 5-year warranty
  • Heats water quickly
  • Well-designed
  • Easy to use LCD display and temperature setting

Cons:

  • You’ll need a decent amount of water flow
  • There have been a few reported issues with fluctuating temperatures

3. Compact Hygger Submersible Aquarium Heater

This is the first of two Hygger aquarium heaters on our list.

Simply put, this is just a solid and small heater. There really isn’t one specific thing that will blow you away, it just does its job.

It might not be as flashy as some of the other heaters on our list, but don’t let that fool you. This is a fish tank heater that packs a punch (provided you use it with the right tank size).

It uses a dial on the power cord to adjust the temperature and you should expect the water temperature to never vary more than 2°F. It has a temperature range of 75°F to 91°F which should be enough to get the job done for most tanks.

The Hygger comes with an auto shut off feature in case any issue occurs with the heater, or if the water temperature rises above 2°F from where it’s set. When this happens it will automatically kick back in once the temperature drops below 2°F from the set point as well.

This is a submersible heater and it comes with very well-made suction cups that make it easy for you to attach it to the side of the tank.

Your three wattage choices with the Hygger are 50W, 100W, and 300W.

Pros:

  • Affordable option for most tank owners
  • Reliable temperature safeguards
  • Solid suction cups that ensure it will stay attached to the side of your tank
  • Hygger says you can expect at least 3 years of service from this aquarium heater

Cons:

  • Feels a little dated compared to some of the other heaters on our list
  • Can only be used in glass tanks

4. Eheim Jager Aquarium Thermostat Heater

This is another solid aquarium heater that is well-rounded and won’t let you down. It also comes with a very attractive price tag which can make it a good buy for a lot of new owners who don’t want to plunk down the additional cash for something like the Cobalt Neo-Therm.

The Eheim is fully submersible and comes with the standard safety features that you would expect from all of the best aquarium heaters. This means if the water temp exceeds the safe range of fluctuation, this will either kick in or turn off.

There are plenty of wattages that you can get with this heater. Here they are:

  • 25W
  • 50W
  • 75W
  • 125W
  • 150W
  • 200W
  • 250W
  • 300W 

It also has a nifty feature that will make sure it doesn’t run dry. If the water level drops below an acceptable point it will turn off to prevent any issues that could compromise your tank or the life inside it.

You’ll also find a shock-resistant and shatterproof glass design which will give you peace of mind. Honestly, at this point this is something we expect from pretty much all of the best aquarium heaters, but to have this available at such an affordable price point is nice to see.

There’s nothing about this heater that will knock your socks off, but that doesn’t mean it’s a bad thing. It’s affordable and does the job, there’s nothing more that needs to be said.

Pros:

  • Low water auto shut off feature
  • Comes standard with a 3-year warranty which is very competitive
  • The temperature fluctuation is very reasonable

Cons:

  • Has a pretty large footprint in your tank

5. Hygger Digital Titanium Submersible Aquarium Heater

This submersible fish tank heater by Hygger is a departure from a lot of the other designs on our list.

While a lot of the other heaters are plastic and feature a dark design, the Hygger stands out. It features a titanium heating element that can work in fresh and saltwater. This design makes it very resistant to any of the standard seawater issues that plague a lot of other heaters.

That also means it’s very durable. Titanium is no joke!

There are four wattage selections with the titanium Hygger:

  • 50W
  • 100W
  • 200W
  • 500W

One of the other features that makes this heater stand out from the pack is its massive temperature range. A lot of the best aquarium heaters have maybe a 20°F-30°F range of possible water temperature options, but the Hygger blows that out of the water.

We’re talking about a range of 32°F to 104°F.

That’s easily best in show and will cover pretty much any kind of aquatic life you house in your tank. It also comes with very effective temperature control and monitoring system.

You can expect very little water temp fluctuation with this heater. It’s pretty much always going to be within 1°F of what you set it to.

This is why it’s one of the best aquarium heaters on the market and a no-brainer to be included on this list.

Pros:

  • Absurd (in a good way) temperature range
  • Very little water temp fluctuation
  • Durable build
  • Unique design

Cons:

  • Can only be used for glass tanks
  • Limited mounting/housing options

6. FREESEA Heater with LED Temperature Display

Last but not least, we have the FREESEA small aquarium heater. This is a very well-rounded option that can be used in tanks ranging from 1-50 gallons and comes at a very reasonable price.

This submersible heater comes with a very attractive and compact design that can be tucked pretty much anywhere in your tank. We think it’s one of the best-looking heaters on the list.

Despite the fact that this device is on the small side, it has a very impressive temperature range (second best on our list) of 59°F to 94°F. We honestly don’t know how they pulled this off!

It has a great LED display that makes it easy to monitor the water temperature in your tank without being a distraction.

The different units come with a watt range from 50W to 300W and have all the standard safety features that you would come to expect from a quality manufacturer.

The biggest downside we can find with this heater is that it only comes with a 12-month warranty. However, we can’t really blame FREESEA here because it’s so affordable and offers such a wide range of functionality. 

Pros:

  • Fantastic value for the money
  • Attractive design
  • Well-made LED display with temperature setting
  • Impressive temperature range

Cons:

  • The heater needs to be submerged all the time to get results
  • The 12-month warranty is the lowest on our list

What To Look For In An Aquarium Heater

Now you’ve seen our list of the best aquarium heaters, now let’s take a moment to go over what features you should look for when making your decision.

Level Of Safety

We put this first because in our opinion it’s non-negotiable. All of the best aquarium heaters have a very high level of safety and reliable safety features.

You see, some tank owners are fine risking it with a cheap heater that works most of the time. 

That’s not us.

We don’t compromise on the safety and health of the aquatic life in our tanks for any reason. That’s just how we roll.

The difference in price between a cheap fish tank heater that works most of the time and a high-quality one that works all the time is pretty minor. The best heaters will last you a few years, so why take the risk over twenty bucks?

The main safety features you’re looking for in are the ability to automatically shut off if the temperature gets too high, or the water level is too low. Any aquarium heater that can’t provide this isn’t worth buying.

You’ll also want an easy and reliable way to monitor the water temperature, and an indicator light to see if your heater is on or off. These days this usually comes in the form of an LED or LCD screen that makes it easy for you.

Wattage In Relation To Aquarium Size

You probably noticed that in our list of the best aquarium heaters we included the wattage in every product review. If you’ve never bought a heater before you might be wondering why that is.

The wattage of your heater is an indication of the amount of power output it has. Simply put, it’s an indication of how well it can heat the water in your tank.

You don’t want to get an aquarium heater that’s too weak for your tank, and you don’t want one that’s too strong either.

The general formula is 3-5 watts per gallon of water in your tank.

To put it another way, here’s a chart for your reference:

Tank SizeHeat Increase: 9ºFHeat Increase: 18ºFHeat Increase: 27ºF
5 Gallon Tank25 watt50 watt75 watt
10 Gallon Tank50 watt75 watt75 watt
20 Gallon Tank50 watt75 watt150 watt
25 Gallon Tank75 watt100 watt200 watt
40 Gallon Tank100 watt150 watt300 watt
50 Gallon Tank150 watt200 watt200 watt x2
65 Gallon Tank200 watt250 watt250 watt x2
75 Gallon Tank250 watt300 watt300 watt x2

Water Temperature Control

You rarely see heaters on the market these days without the ability to choose a specific temperature, but it’s worth mentioning in case someone tries to gift you an ancient hand-me-down.

Having the ability to tweak the temperature as you see fit is absolutely necessary for any tank owner. Different aquatic life needs different water temperatures in order to thrive, and you need to be able to provide this.

The Price

This is a bit obvious but we included it because we think it’s important to frame pricing expectations when it comes to the best aquarium heaters.

As you probably guessed from our mini-rant before, we’re never a fan of going with the cheapest option if it means sacrificing the safety or well-being of the life in your tank.

However, we get that money doesn’t grow on trees. 

This is why we’re so happy with our list. It includes quality heaters of various prices and gives you the option to pick what is best for your tank, and your wallet.

When considering the price it’s worth being mindful of the possibility that you might decide to get two heaters. We’ll go into this more in the section below, but if you decide to go this route you’ll obviously need to budget for that.

Frequently Asked Questions About Fish Tank Heaters

If you’ve never purchased an aquarium heater before you probably have a few questions. While we can’t read your mind (that would be cool though huh) there are a few questions we’ve heard a lot over the years.

We’ve answered these questions below and will add any others that we hear often to the list as time goes on. If you have any other questions feel free to reach out to us directly!

How Many Heaters Do I Need?

This is a question we get a lot because there’s a lot of differing information floating around out there.

When you look at all of the aquarium heater product pages it says each of them can heat your tank on their own. But when you talk with some experienced aquarists, you hear that a couple of heaters is a smart idea.

So which is it?

Here’s our stance:

Every one of the best aquarium heaters can warm up the water in your tank on their own. It’s not false advertising by the manufacturers.

But if you can manage it, getting two is usually a good decision. This makes it super-easy to keep your water warm no matter what conditions you live in.

Each heater won’t have to work as hard, and if one of them breaks down you have another fully capable one as a backup.

If you decide to do this, make sure you get two heaters that have a wattage output well within the recommended total for your tank size.

How Do I Set It Up?

Getting your aquarium heater up and running is a lot easier than you might think. Heaters these days are pretty much ready to go out of the box, there are just a few things you’ll want to do first.

Note: It’s important that you do all this without fish in the tank. This might be obvious to some of you but we need to mention it just to be safe.

  • Make sure everything looks good. Before you drop any electrically powered devices into your tank you want to make sure it passes the eyeball test. This means everything looks like it should, there are no funky wires sticking out, and it generally looks like it does on the box.
  • Clean the glass where you’re going to mount it. The glass on the inside of your tank likely could use a quick scrub to make sure the suction cups can stick easily. You’ll want to be sure the heater is near the filter inlet or where any warm water flow is occurring.
  • Follow the instructions to mount the heater. For the most part modern aquarium heaters these days (submersible at least) are mounted in a similar fashion. With that being said, follow the instructions to make sure it’s mounted properly and securely.
  • Give it a moment. Your fish tank heater will probably need to settle in before you turn it on. Each manufacturer has their own recommended time, so stick with that you see in the manual.
  • Do a temperature test. Use a thermometer to check what the water temperature is before you turn it on. This will give you a baseline you can use when ensuring that your new heater is working.
  • Turn it on and wait. Set your heater to the temperature you would like your tank water to be, and wait roughly one day before checking it again. Once you’ve confirmed that your aquarium heater is working properly, you can add your fish to the tank.

How Do I Make Sure It’s Working Properly?

The short answer is that you should take an external thermometer (not associate with your heater) and use it to verify that your heater is working and giving you an accurate reading.

This is something you should be doing on a consistent basis just to be sure. It doesn’t take very long and will go a long way when it comes to keeping your aquatic life safe. A quick check every day won’t take very long and will give you peace of mind (especially when your heater is still on the new side).

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