The Best Aquarium Heaters That You NEED To Know About!

When it comes to our aquariums, we want the best for them, don’t we?  We want our fish and plants to live a life of luxury, dining on the best food, sheltering in the best caves money can buy, and enjoying luxurious gravel and filter systems. 

But have you ever thought your fish might be cold? It might sound silly to some of you, but for those with bettas or tropical fish, your waters might not be warm enough! Cold water for these fish can be detrimental, causing stress and all kinds of health-related problems. That’s the last thing any of us fish owners and lovers want!

There are so many different types and prices of heaters that it can be challenging to know which heater is best for your fish. Luckily for you, that's where we come in! We have scoured the market and are proud to bring you the best aquarium heaters available! These heaters are suitable for a range of budget and tank sizes, meaning you never need to look anywhere else for an aquarium heater! 

Stick with us and keep on reading to meet your new heater and keep your fish in warmer and happier waters

The Best Aquarium Heaters on The Market

Now that we have covered the basics and hopefully helped you determine what type of heater you need for your tank let's look at the best heaters on the market to keep your water warm and perfect for your fish!


Kicking off our list is Fluval’s E Electronic Heater. The 300-watt heater is fully submersible and perfect for larger tanks. It can safely handle a 100-gallon tank with temperatures ranging from 68 degrees to 93 degrees Fahrenheit. 

And for those of you with smaller tanks, there is still an option for you too! There are four versions of this heater, all ranging in wattage and capabilities. The different types all state their maximum capacity, too, so you don't need to worry about buying the wrong one! For those with smaller 15-gallon tanks, we recommend the 50-watt heater. 

Fluval’s heater can be used in both freshwater and saltwater aquariums, too, offering plenty of choice and flexibility. Should you ever want to change your tank, you won’t need to splash out on a new heater! The heater features dual temperature sensors that offer you real-time water temperatures that are accurate too! Never again will you need to worry or wonder about the temperature of your tank's water; simply check at a glance! 

Checking and adjusting the temperature of your heater is easy, too, thanks to the LCD temperature screen. You can view in Fahrenheit or celsius too, and switch between the two as you see fit. The screen is easy to read and use, too, perfect for all users! For those that want peace of mind when they purchase,  Fluval’s heater comes with an impressive 5-year warranty, so should anything go wrong, you can rest easy knowing you are covered!

And should you need any more reassurance, the heater features fast heat technology and a safety shut-off, so you are unlikely to find yourself in overly hot water with this heater! Fluval’s heater also features an integrated fish guard that protects your fish and invertebrates from hurting themselves on the heater. It is also protected from any big fish and their shocks. What more could you want from your new heater?

Setting up the heater is easy, too, although it's worth mentioning that the user guide suggests you don’t place the heater horizontally. Installing it horizontally can void your warranty too and leave you in the cold! Be sure that you have enough space in your tank to install the heater vertically before purchasing it.  

After an easy-to-use and reliable aquarium heater? Then look no further than Fluval’s E Electronic Heater! 


  • 5-year warranty - don’t need to worry about anything going wrong 
  • LCD display - for accurate and easy temperature readings and control 
  • Integrated  fish guard - prevents fish from contacting the heating element and  protects it from bigger fish
  • Accurate temperatures - never are kept in the dark with this heater
  • Suitable for freshwater and saltwater aquariums - don’t need to buy a new heater should your aquarium change


  • Can’t set up horizontally 


After an external heater that will keep your water temperature stable? Try Hydor’s in-line heater today! Its unbreakable plastic construction ensures that you don’t need to worry about it breaking any time soon! The heater comes in various sizes, ensuring you can find the perfect one for your tank size. It's incredibly easy to use, too, allowing you to adjust the temperature with the dial quickly and easily.

Having the heater outside the tank removes the wet-hand dilemma and ensures that you always have precise temperatures. Hydor’s external heater is easy to install and uses a polymer PTC heating element. You won’t need to worry about your water overheating; instead, you can set the thermostat and forget about it! These elements have a self-limit, meaning they will never get warmer than the preset level.

The heater will also ensure the water is filtered and moved to ensure the temperature remains the same throughout the whole tank. You won’t need to worry about pockets of cold water with this heater! As it's an external heater too, you save some space in your tank! You can use the saved space for more fish, accessories, or filters. Speaking of filters, you will need to use a canister filter with a Hydors heater, putting some customers off. 

Also, the heater cannot be installed horizontally, so you need to make sure your tank is long enough to accommodate it. You will also need to consider where you place the heater, as if it's placed behind the tank, you will struggle to see the indicator light. Despite this, it's still a fantastic heater and the perfect solution for those with limited space in their tanks! Rest easy and choose a worry-free external heater like Hydor’s. 


  • Durable - unbreakable plastic construction means you never need to worry about it breaking
  • Easy to use - temperatures can be adjusted easily and quickly 
  • Easy to install - perfect for all levels and those after a quick installation
  • Safe - will never overheat the water, ensuring the safety of your fish
  • Saves space -leaves you with more space in your tank


  • It can’t be installed horizontally.
  • If placed behind the aquarium, you can’t see the indicator light.


For those that want a durable and sleek heater, Cobalt has the one for you! Their Neo-Therm heater comes in a range of wattages and features a super-flat design you are sure to love. The small heater can reach up to 96 degrees Fahrenheit in larger tanks and support larger tanks. The heater needs to be placed vertically to avoid voiding the three-year warranty it comes with.

The warranty will provide you with peace of mind while you use it, so ensure you have the capacity to place this flat heater vertically. You get extremely accurate readings with this heater; you can expect them to be within 0.5 degrees of the temperature, providing you with precision and reassurance that your water is at the correct temperature.

You can check the temperature easily with the easy-to-read and easy-to-use LCD display. Cobalt’s heater automatically shuts off before overheating, too, ensuring your safety and the tank's safety at all times. The durable case also features a shatterproof outer casing for outstanding durability and reassurance that your heater will stand the test of time! 

It's worth noting that some customers reported issues of the malfunctioning of the 200W heater. The problem was not widely reported, but what kind of review would we be if we didn’t include the bad too? Aside from this issue, you can expect insane durability, accuracy, and reliability, all in one easy-to-use filter! What more could you want? 


  • Range with wattages - one for every size tank
  • Super flat design - saves space in your tank and provides a modern design
  • Extremely durable - shatterproof outer-casing ensures there is no damage 
  • 3-year warranty - provides peace of mind while using it 
  • Accurate temperature display - no need to worry about errors or incorrect readings


  • Some customers reported issues with the 200W version.


For those after a reliable and submersible heater, look no further than EHEIM’s offering! The durable heater is made from shock-resistant and shatterproof glass, so you never need to worry about breaking during use! It's an incredibly safe heater that automatically turns off when your water level dips too low, avoiding any potential issues! Simply adjust the water level, and your heater will start to work again.

There is also an on/off indicator light that will allow you to check the temperature quickly and with minimal effort from yourself; what more could you want? The heater features a  truTemp dial that ensures you have precise and accurate temperatures at all times! You won’t be wondering if the temperature is correct; you can rest easy and leave your tank in peace!

You can expect the readings to be within 0.5 degrees of accuracy. We don’t often see this level of accuracy on such affordable heaters, making it a fantastic option! You can expect years of use from this heater too. Many customers reported years of trouble-free and reliable use. Why not get exceptional value for money and longevity all in one easy-to-use heater?

Some customers did note that the heater is quite long, making it difficult to be installed horizontally. Be sure you have ample space for the heater before you purchase it! While you might have luck in larger tanks, those with smaller tanks will find it easier to install vertically (and need space for it). After an extremely durable and accurate heater that isn’t going to break the bank? Then grab EHEIM’s heater today! 


  • Durable - shatterproof and shock-resistant construction
  • Accurate temperatures - stays within 0.5 of your set temperature for wonderful accuracy
  • Auto-shutoff - prevents any issues when the water level is low 
  • On/off indicator - allows you to check the temperature quickly at a glance 
  • Long-lasting - customers have reported years of successful use


  • Difficult to set horizontally due to how long it is 


This helmet is another amazing option for you to consider in your search. The Pro-Tec Ace has absolutely everything you need when it comes to protective headgear which is why is it no surprise that it is such a popular choice amongst surfing enthusiasts of all levels. With a high-density injection-molded ABS shell and a dual-density waterproof EVA liner, this helmet is highly equipped to keep your head safe from all sorts of impacts in a wide variety of water sports.

As a surfer, I’m sure you will appreciate the helmet’s 15 open ventilation holes and the highly effective drainage system. Not only that, but its soft, thick cushioned padding and adjustable rear-fit makes for optimum comfort and practicality. This layer provides an additional level of protection to the highly durable outer shell, allowing for maximum safety and reliability. The helmet also boasts removable cupping ear guards which can be essential to a surfer that is traveling at a high speed amongst the water.

If it’s style that you’re looking for, this helmet is great as it comes in a range of colors at both a matte and gloss finish. If you’re undecided, we think that the matte black option is particularly sleek, unless you want something brighter. Tried and tested in all kinds of water-based elements and circumstances, this helmet is proven to protect within a range of dangerous conditions.


  • Stylish appearance
  • Durable
  • Proficient ventilation system
  • Extra protection with the deep padding
  • True to size


  • Reviews state some issues with the ear coverings

Top 5 Aquarium Heaters - Buyer's Guide

Now that we have showcased our top 5 aquarium heaters, let's look at all the things you need to know about aquarium heaters, how they work, and which one you will need.

Why Do I Need an Aquarium Heater?

Now you might be wondering, this doesn’t sound like something I need, but there are many reasons why you should have an aquarium heater! Before we look at the fantastic heaters on the market, let’s look at these reasons. You will have probably seen that most aquariums these days will have a heater.  At their most basic level, a heater stops the water from dropping past a certain temperature.

At least with a heater, you can expect and rest easy knowing that the water stays at the same temperature! While you might start with room temperature, harsh weather or poorly insulated rooms can soon see the water temperature changing. Some fish species will also require the water to be warmer than room temperature, such as some tropical fish, meaning a heater in these cases is essential! If you are keeping bettas or tropical fish in a tank, then you need a heater! We recommend buying the best one your budget can afford to replicate the warmer climate your fish will be used to.

Another reason you need a heater is to prevent your fish from getting stressed. Properly maintained water temperatures are what fish are used to, and constant changes can stress them out. Just like with humans,  stress can be detrimental to your fish’s health and cause serious problems down the line. 

The size of your fish tank will play a role here too. In smaller tanks, temperature changes can happen quite quickly, with the whole of the water dropping degrees and causing your fish grief. However, the process is much slower in larger tanks, and you have time to rectify any mistakes.  While a smaller tank can seem easier, a larger tank will be more forgiving for beginners and allow you to learn without harming your fish! 

Best aquarium heaters

Different Types of Aquarium heaters

You can choose between several different aquarium heaters, and all have specific locations that they need to be placed. Let’s take a look at these! Each type will have its pros and cons, and you must weigh these up and select the heater that suits your needs. 

Immersible Heater

Immersible heaters are the most common aquarium heaters on the market and often a  favorite with beginners! It hangs over the top edge of the tank with a glass tube containing a heating element placed in the water. You often find this type of heater in aquarium kits that you can purchase with or without your tank.

These affordable heaters require an opening in your aquarium hood, which, thankfully, is a common design in aquariums these days. Although these heaters are popular, you need to be careful with them. Your heater needs to be properly secured. Bumping it can cause the glass to break, which can lead to fires! They also run the risk of electrocuting you and your fish if you aren’t careful!

Generally, fish deep underwater are safe from electrocution when lightning strikes in their natural habitat. However, it is still possible for them to get electrocuted. While most tanks will accommodate the immersible heater, it's not safe to use for brackish or marine aquariums. The salt can enter the tube, leading to corrosion or an electrical short, which again can cause all sorts of problems!

While they are an excellent choice, we strongly advise caution and appropriate placing of the heater to avoid any potential safety issues!

Submersible Heaters

Up next is the submersible heater that you place directly in the water. It's far more efficient than other types, and you get more control of the heater, allowing you to position it how you see fit. You will need to ensure there is enough space around the heater. The last thing you want is your fish getting caught between the heater and the side of the aquarium or the gravel!

A submersible heater should not touch the gravel either. The difference in heat between the heater and the gravel can cause the heater glass to crack and poses a safety risk. 

In-line heater

The in-line heater is an external heater that will involve a sump or filter. The lin-line is placed inline between the sump or filter and the tank itself. These types of heaters are effective in larger aquariums and are frequently chosen. 

However, in-line heaters can be complicated to install, and you should expect the setup to take a while. But many users think this complicated installation process is worth it, as your fish won’t come into contact with the heater, keeping them safe should anything go wrong. 

In-sump heater

Following on from in-line, you can have a heater in the sump itself. You will get much of the same benefits we saw with the in-line pumps, with many users finding them easier to maintain! 

It’s worth noting, though, that the sump will require more space in your room than other heaters. Be sure that you have plenty of room to accommodate it before you splash the cash!

In-filter heater

Sometimes you can purchase a filter with a heater built-in. While these are convenient, you need to ensure that the filter can keep the water at the temperature you want. There’s no point purchasing one if it won’t make the water hot enough! 

In-filter heaters can sometimes be larger than other filters, so be sure to measure your space before purchasing to ensure you can accommodate it in your room and tank. 

Substrate heater

These types of heaters aren’t very common in the US but are still worth mentioning! You tend to see substrate heaters in Europe more, and they work by burying the heater beneath the gravel. You usually use wires as the heating element, which can prove tricky for some tank owners! 

Once installed, the heat travels through the gravel to the water. It’s not suitable for everyone, but for those with planted tanks, you might find a substrate heater your best choice. These heaters prevent the roots from being too cool in the gravel, hindering their growth and health. 

Final Thoughts 

And just like that, we have come to the end of our review today! As you can see, there are plenty of fantastic options when it comes to purchasing your new aquarium heater. 

Whether you are after an immersible heater or an in-filter one, there is sure to be a heater out there that suits your needs! Remember to measure your tank and space around it to ensure you have ample space for your new heater! Whichever you choose from today's list, we are sure you will have a fantastic heater that will keep you and your fish happy!