Fish are rather different creatures from us. Unlike humans and the majority of land animals, they do not produce their own body heat and rely instead on the temperature of water to thrive. Naturally, this makes it pretty important for fish owners to keep their aquariums at the right temperature!
Only in very particular circumstances, and with particular fish, will the ambient temperature of your home be suitable. In the vast majority of cases – you’ll need a heater. Selecting the best aquarium heater isn’t particularly difficult, though there are some important things to bear in mind.
Whether you ultimately go for an immersible heater, a submersible heater, a substrate heater or a filter heater will depend on a range of factors. However, it doesn’t stop there. You’ll also have to consider heater size, something which is directly related to the size of your tank, be it three, five, ten gallons or higher.
Heater size will also depend on the temperature of your room. Luckily, there are some very simple calculations which can determine your heater size from these two figures.
The 10 Best Aquarium Heaters
1. Cobalt Neo-Therm | Best for Durability
We’re kicking off our list with a relatively high range model. The Neo-Therm is a submersible heater that can be pretty pricey, but happily worth every penny. Highly accurate to within around 0.2 of a degree, this heater is also virtually indestructible, which in the world of aquarium heaters also means that it’s safe.
And as if such durability wasn’t enough, the Cobalt Neo-Therm also comes with an excellent warranty, which is always welcome at the higher price range. With an otherwise elegant flat and compact design, this heater is let down a little by suction cups with a tendency to slip, but this is naturally a minor gripe.
- Flat and Compact
- Very accurate
- Good warranty
- Suction cups can be insecure
2. Hygger Aquarium Heater | The Best for Safety
With aquarium heaters, there’s a natural concern about safety (see our FAQs for more) and this is understandable given the horror stories one hears about explosions and electrocutions. While any such fears are unfounded in most cases, a little piece of mind can go a long way. The Hygger aquarium heater has three things going for it in this department, a durable body, a simple and effective interface that lies outside of the water and an auto cut-off feature which kills the power upon overheating.
This is also a stable and compact heater which holds fast to the inside of the tank. While we’re on the topic of design, it might be worth pointing out that this heater also has a rather short cord connecting its probe and heater, which could be the reason it is also very slightly inaccurate, sometimes – though not always – being around 2°F off.
- Durable body
- Ease of use (no wet hands)
- Holds fast to tank
- Cord connecting heater and probe short
- Accuracy very slightly off
3. Eheim Jager | The Best for Quick Monitoring
This Thermostat heater from Jager is another one with some helpful safety features: it cuts off in the absence of moisture and is made from shatter and shock proof glass. However, the reason it makes our list is the comparatively simple feature of it’s on/off light. This actually eliminates a very common and irritating problem with heaters – guessing if they’re on or not! With a mere glance from across the room, you’ll know. This means you can address any issues as and when they arise.
In terms of downsides, this is not the heater to go for if you want something compact. It’s also not one to simply plug in and use, as its accuracy is very dependent on accurate calibration. If you’re willing to read that manual, however, this is a great heater.
- On/Off light
- Cuts off in absence of moisture
- Made from shatter-proof glass
- Glass “jackets” which expand heating area
- Accuracy completed dependent on calibration
4. Fluval M | The Best for Aesthetics
You might think including a heater for aesthetic value on this list is a little superficial, but what is a fish tank if not aesthetic? At the end of the day, you don’t own fish for a good conversation! This offering from Fluval has a very nifty feature to recommend it, namely a built-in reflective technology enabling it to reflect the general color pallet of your tank. Heaters are often unsightly things. Not so here.
This heater is also compact and will hold fast to your tank (even if, with that mirror technology, you’d maybe even prefer it was larger!). Its downsides largely concern its relative fragility compared to some of the other heaters on our list. If you handle this roughly outside of the water, it could easily smash. Inside the water, too, you might want to be careful with bigger more powerful fish, the owning of which should possibly discourage you from getting this heater. This is also another heater with a generous warranty.
- Reflective technology
- Holds firm
- Good warranty
- Can be fragile out of the water
- Can be fragile in the water with big fish
5. Marineland Precision Heater | Best Budget Heater
Not everyone is in the fishkeeping business to raise a veritable shoal inside a fifty gallon tank, and for smaller tanks, the simple of the matter is you don’t have to go expensive. This isn’t to say that you can be careless – temperature regulation is still of paramount importance – but if you want a budget heater, the Marineland Precision offers you a remarkable amount for the price.
For one thing, it’s durable (although there has been an alarming number of reports of damage while shipping) and comes with a mounting bracket which will hold firm. It also features a fully functional auto cut-off feature and a display that is nice and large. It has been noted, however that this display, though not the actual temperature, can be a little off. Overall though, this is great for the price.
- Very affordable
- Mounting bracket is fully secure
- Display (though not actual temperature) can be off
6. Orlushy Submersible | The Best All-rounder
What has this Orlushy submersible heater appearing in our list as the best all-rounder is its wide temperature range and effective automatic cut-off. This combination ensures the Orlushy can be used with very good accuracy in tropical, marine, salt-water and freshwater tanks, and is suitable for your cold water, tropical or temperate fish.
This heater is also discrete, the glass portion being almost invisible in the water and, although glass, it’s actually pretty durable and shatter proof. In terms of downsides, it has been reported that this can get pretty hot upon first use (whether this is a design flaw or the result of few faulty products, we don’t know) and also the thermometer can be little off in relaying the temperature. Overall though, this is a solid heater.
- Wide range
- Discrete in the tank (transparent)
- Shatter-proof glass
- Can get very hot upon first use
7. Aqueon Adjustable Pro | Best for Discretion
On our list so far we have had a heater included for durability and another for ease of monitoring. To be honest, this heater from Aqueon could just as well have been included for these reasons, being both durable and including an effective lighting system that shows green when heating and red when not. The Aqueon Adjustable Pro is ultimately included on our list, however, because it just blends so well into the aquatic environment.
The Aqueon adjustable pro has a limited lifespan, though it’s cheap enough for replacements to be on a par with purchasing a longer lasting model. Some people have reported issues with a quality drop following a new manufacturer as well.
- Blends very well in tank
- Useful on/off lighting system
- Very durable
- Limited Lifespan
8. Freesea Submersible | Best Small Tank Heater
For a small tank heater, you want a heater that uses a reasonably low amount of power and is not too bulky, allowing it to fit into the tank. This model from Freesea performs on both counts and does so pretty efficiently into the bargain.
Related: Top 5 Gallon Fish Tank Filters
This model also features an automatic cut-off which works reliably, making the thing a good deal safer. This model, however, is potentially unsafe for the smallest fish as the coils can become a bit of a trip. For this reason, it’s best to avoid if you have the smallest fish or fry. The power cord is also pretty short, which can be annoying as this might decide for you where in the room your aquarium goes. Luckily, however, small tanks aren’t as difficult to move around or find a space for.
- Reasonably low wattage
- Discrete and compact
- Short power cord
9. Vivosun 300W | Best “Smart” Heat
The Vivosun 200W is another great one for safety, featuring the external temperature control and the durable, explosion-proof design that has already earned other heaters a place on our list. The reason this model appears, however is the futuristic technology that has been integrated into its design. This heater contains an IC chip which intelligently controls the temperature to an impressive degree of accuracy.
You might also have noticed when reading this list that the temperature displays on heaters, which nevertheless control the temperature accurately, can often be a few degrees out. This would seem to be a very common problem and it is present here also. This heater also has a screwed-on top. There is no evidence that this has caused any problems but certain users have been nevertheless concerned that a submersible heater is sealed with a screw! Otherwise, this is an excellent heater and well-priced for the innovative technology you’re getting.
- IC chip which controls temperature
- Corrosion and explosion-proof
- External temperature control
- Screwed-on top
10. Viberit Aquarium Heater | Best for Fast Heating
Heating up quickly can be important, and proves you have a more efficient heater in your hands, which is good for your electricity bill! This model from Viberit offers precisely that, heating up quickly and correcting temperature drops faster. This is a mechanism aided by an automatic cut-off.
It’s also another model that has a “smart” element, here meaning a handy memory function which will retain your settings in the event of a power down. It’s also very easy to install, with little more to do than simply plug in and go.
In terms of downsides, the Viberit can heat a little unevenly in the very biggest tanks (even though it isn’t a specifically designated small tank heater) and there have been some reports that the temperature will drop right down to the ambient, after the auto cut-off, before it turns back on again. This slight awkwardness aside, this is an undoubtedly fast and efficient heater.
- Heats up quickly
- Efficient power usage
- Memory function (retains settings in the event of a power down)
- Easy to install
- Temperature can fall all the way to ambient before device switched back on
The Best Aquarium Heater Buying Guide & FAQs
As you will have been able to tell from the list, there are various types of heaters out there and various sizes in which they come. There are also different types of fish which prefer different temperatures and different tank sizes which should be heated differently. If all of this appears to get a little confusing, you might want to read on for our helpful FAQs.
What Size of Heater Should I Get?
|Tank Size (gallons)||Wattage|
Having examined the best aquarium heaters out there, you will have noticed they have very often come in multiple sizes. Selecting the right size, thankfully, is a simple enough process, though you must remember also to adjust for room temperature.
Deciding what size of heater to get is a two stage process. First, you have to decide upon a wattage based upon the size of your fish tank or aquarium. The following table should be of use:
But the process doesn’t end there. After wattage has been determined. It’s time to correct for your room temperature. If you live in a year-long hot climate you’re going to be in quite a different situation from those living in a seasonal climate or those in colder locations. The above table is a rough guide and more wattage will be required to increase the temperature more. With the above table letting you know what equipment you will need, it’s time to settle on target temperature. Once you have this, subtract the room temperature and you will have the amount that you will have the temperature to which you need to raise your water. Generally speaking, the heater wattages outlined in the above table will be sufficient to do this, but you will have to adjust them accordingly in order to raise things to the right temperature.
What is the Most Reliable Aquarium Heater?
Types of aquarium heaters can, as you will have noted over the course of our list, vary quite a bit. Each type of heater has its own specific benefits and there’s a definite limit to how much you should generalize.
That said, it is possible to come up with some general rules regarding heater efficiency. Submersible heaters, for example, are generally the most efficient. Being completely covered with water they offer a more even heating of the tank, something which, in the case of larger tanks, can be very important.
Generally speaking, partially immersed hang-on heaters are the least efficient due to their positioning and the porting of their body outside of the water. That said there will be many cases where a hang on might be preferable, especially for smaller tanks, so keep that in mind.
The truth is there is no one universally most reliable heater, it depends on many other factors. Your best bet is to consider your tank and your fish and go from there.
To What Temperature Should I Heat My Tank?
There are several factors that will influence the answer to this question, the main one being what type of fish you have. As mentioned above, fish are cold-blooded creatures whose body temperature will align with that of their aquatic surroundings.
Fish as a grouping of animals contains more species that we could either count or can hope to discover any time soon. Unsurprisingly, that makes for a lot of variation throughout this massive group when it comes to what temperature they are most comfortable at.
Naturally, you’re going to want to include fish in your aquarium that all share a similar preference. There is, after all, no way to have different temperatures at different parts of the tank!
Generally speaking, you’ll simply have to work on a case by case basis as you purchase your fish. However, this information will always be readily available wherever you get your fish, as well as some tips on what fish share that preference.
That said, fish generally fall into three rough categories where this is concerned. It’s wise to mix fish that are in the same category. These are:
- Cold Water Fish, which prefer temperature below 68 F
- Tropical Fish, preferring 75-80 F
- Temperate Fish, which can survive over a higher ranger, often overlapping with the above
Related: Ultimate guide for best aquarium chillers!
Are Aquarium Heaters Safe?
This is a good question, and one asked by nearly everyone that gets a bit concerned about the combination of water and electricity. The answer, thankfully, is yes. Aquarium heaters are specifically designed to be able to operate in an aquatic environment. But the appropriate caution has to be taken.
When you’re changing the water in your tank, it’s important to unplug your heater at least thirty minutes before. This is because a running heater not submerged can cause the glass to crack, leading to immediate damage and the risk of electrocution through the medium of the water. The dangers here hardly needs to be explained, so take care!
Do Aquarium Heaters Use A Lot of Electricity?
This depends very much on the wattage of your heater, and how many you are using. In turn, this, therefore depends upon how large your tank is. You will naturally use more electricity heating a larger tank. As a rough metric, you can expect to use around 150 kWh per year for a small ten gallon tank. This is can increase all the way up to 400 kWh for a large 50 gallon tank. As there are various factors that will influence this – such as room temperature and type of fish – it’s best to make a rough judgment based on these ballpark figures.