Keeping an aquarium is no easy business; you need a bunch of equipment to maintain one, and an aquarium heater is one of them.
It is not good enough to choose any heater you can get your hands on. No, you need to be picky about the heater you use to warm your cold-blooded pet buddies, for reasons we’ll see later.
We’ll help you get nothing short of the best aquarium heater for your fish by providing you with a list of our handpicked products.
Let’s get started.
Why Do You Need an Aquarium Heater?
Fish are cold-blooded, which means they can’t regulate their body temperatures and need a source of external heat, which is where the heater comes in.
Now, fish can survive low temperatures for some time (they are subject to it frequently in the wild), but it taxes their health.
Cold temperatures lower their metabolism and make them act sluggish; even worse, it stresses their system and could compromise their immunity.
More than the coldness, it’s the rapid fluctuations in temperature that are more harmful to your fish – the only way you can ensure a steady temperature is through an aquarium heater.
While some fish, such as the goldfish and axolotl, prefer colder temperatures and do not require a heater, tropical fish such as bettas, discus, and angelfish may need one, especially if you live in a cold area.
Tropical fish need the temperature to be between 75° and 80° F; they will suffer if it goes below 60° F. Generally, most fish like the temperature to be above a comfortable 70° F.
What to Look for in an Aquarium Heater?
Safety Features
We’ll tell you to focus on this one first – a malfunctioning heater is such a hazard for your fish. There are horror stories of aquarium heaters malfunctioning and boiling the inhabitants alive!
A broken heater can also cause electrical shocks to the fish as well as to you. This is why we advise you to never skimp on the heater – the filter, maybe, but never the heater.
One of the features you should seek is the automatic shutoff feature, where the heater will turn itself off if the temperature gets higher than desired.
Should the worst happen, and the heater fails, make sure it is designed to fail to off. Failing to on means it will keep raising the temperature to dangerous levels. Conversely, failing to off will just make your fish cold, which is not a death sentence (unless you live in Antarctica).
Heater Type
There are different kinds of heaters out there; the commonest one is the submersible heater, which is meant to be completely underwater. This is believed to be the most efficient.
Then there’s the immersible heater; with it, some part must be above the water. While it is great to be able to adjust the temperature dial without taking it out or wetting your hand, the immersible type limits the number of places where you can install your heater.
The inline aquarium filter heater is another type rising in popularity. It is where the heater is built right into the filter, meaning the outflowing water is not just clean, but also warm.
You also have other types such as the aquarium heating pad and undergravel heaters, which have niche uses.
Durability
We wish for any product we buy to last a long time and not break. If you have some big and strong fish that can knock the heater around, consider getting something durable.
Even you can be clumsy and drop it sometime, so it pays to get something that doesn’t break easily.
Cord Length and Indicator Light
You shouldn’t overlook simple things like cord length and indicator light. The cord length can severely limit where you can place your fish tank and may force you to use an extension cord.
When setting up the cord, make sure to create a drip loop to prevent water from getting into the electric outlet.
Indicator light is important to let you know that the heater is working and keeping your fish warm as intended.
Calibration and Thermometer
Some aquarium heaters can be calibrated by the user; you may actually need to calibrate it before using, or from time to time. It’s a good feature to control how accurate your heater is.
You often need a thermometer to calibrate the heater and make sure it is maintaining the temperature you want; some heaters come with one, sparing you the need to buy one separately.
Wattage
You need to get the proper power rating to efficiently heat your tank.
The rule of thumb is to have 5 watts per gallon for 55 gallons or less or 3 watts per gallon otherwise.
That means a 50 watt fish tank heater is perfect for a 10 gallon tank; you should also take into account how cold your environment is.
Do not exceed the recommended wattage; for stance, do not get a 100 watt fish tank heater for a 5 gallon tank. Risk of overheating is monumentally high with higher wattage per gallon.
Best Aquarium Heaters for 2024
1. Orlushy Submersible Aquarium Heater, Adjustable Fish Tank Heater
The Orlushy Submersible Aquarium Heater is a reliable piece of equipment for your tank at an affordable rate.
While it is mostly targeted at freshwater tanks, it is also one of the best saltwater aquarium heaters you can get.
The dial spans from 68 to 89 °F, with a supposed 1-degree error. The fact that it can be calibrated means you can always make sure it is accurate.
The heater consists of thickened quartz glass with crash padding at the bottom, so it can certainly take some abuse.
The free digital thermometer it comes with is always handy, whether to calibrate it or to ensure it is working accurately.
One issue is it can be difficult to fit into a small tank, so not the best aquarium heater for a 5 gallon tank.
What We Like
- Crackproof with thickened quartz glass
- Can be calibrated
- Free thermometer
- Good price
What We Don’t like
- Not highly accurate
- Difficult to fit into a small tank
What our Testers Say:
It’s a solid heater, but its accuracy is not what is purported. Still, it is usable for most aquariums, with proper calibration and monitoring.
2. FREESEA Aquarium Fish Tank Heater: Small Submersible Turtle Heater with Adjustable Temperature External Controller for Betta | Saltwater | Freshwater
The FREESEA aquarium heater is one of the best mini aquarium heaters you can get your hands on, perfect for tank sizes between 1 to 20 gallons. This small aquarium heater is compact and versatile, meaning you can place it almost anywhere you want.
The temperature can be adjusted between an excellent range of 63-94 °F using an external controller so that you don’t have to dip your hand in the water.
It’s not lacking in safety features, with it automatically shutting off when the temperature exceeds 94 °F or when the top part is out of the water. Still, malfunctions are known to happen.
The temperature is displayed in real-time on the heater but it is not wholly accurate.
What We Like
- Compact and small
- External controller
- Auto shutoff feature
- A good temperature range
What We Don’t like
- Auto shutoff didn’t work in some cases
- Temperature readings are not accurate
- Cord length is just 5 ft
What our Testers Say:
Really handy heater when you have a small tank with not enough room. However, it should be advised against using it in a really small tank, as the risk of overheating is high; the auto shutoff feature was working as intended, but if it malfunctions, the results can be catastrophic.
3. Tetra HT Submersible Aquarium Heater With Electronic Thermostat
This is the best aquarium heater for those who don’t want to worry about calibration or adjustment – just dip it in your tank and plug it in; the heater will maintain the temperature at 78° F.
On the flip side, not being adjustable is a limitation – you only have one temperature at your disposal.
It gets even worse when it does not maintain the temperature it is supposed to maintain – at least with other heaters you can adjust the dial to get the desired temperature.
The good things about it are its compact size, better heat distribution, and auto-shutoff with electrical short.
What We Like
- Aluminum oxide crystals for better heat distribution
- Very easy to use
- Small and inconspicuous
- Pretty affordable
- Auto shutoff with electrical short
What We Don’t like
- Cannot be adjusted or calibrated
- Doesn’t always maintain the said temperature
What our Testers Say:
As feared, it does not exactly maintain 78° F, and the lack of calibration or adjustment means it can’t be corrected. That being said, it is still an easy-to-use heater good enough for most situations.
4. HITOP Adjustable Aquarium Heater, Submersible Fish Tank Heater Thermostat with Suction Cup
The HITOP heater is a sturdy one, with 2mm thickened quartz glass and protective padding at the end. It has a temperature range of 68-93 °F, with moderate accuracy.
It boasts of even heat distribution thanks to its vertical wires. The cord length is somewhat limiting at just 4.9 feet.
While it comes with a sticker thermometer (which looks cool to be fair), you cannot expect it to be accurate since it sticks to the outside of the tank, which can be a tad different from the inside temperature.
What We Like
- 2mm thickened quartz glass
- Comes with a sticker thermometer
- Protective cover at the end
- Even heat dissipation
What We Don’t like
- Cord is just 4.9ft
- Sticker thermometer not an accurate reflection of water temperature
- Accuracy is still lacking
What our Testers Say:
Reliable heater but if you want high accuracy you need to do some monitoring and adjustments. For instance, you cannot rely on the sticker thermometer it comes with.
5. Aqueon Small Aquarium Fish Tank Submersible Mini Flat Heater Up to 2.5 to 5 Gallon Aquariums, 7.5 Watts
This fish tank heat pad is perfectly suited for small tanks that are 2.5 – 5 gallons. Rated at 7.5 watts, the risk of overheating is low, which is an important consideration for small tanks.
On the flip side, many found the heating to be inadequate. Some tried to use it as a 10 gallon fish tank heater with poor results.
And the suction cups caused some issues for some users.
It is something cheap for a 5 gallon fish tank heater, and may probably suffice the needs of your small tank.
What We Like
- Aquarium heating pad for small tanks
- Compact and versatile
- Easy to install
- Little risk of overheating
What We Don’t like
- Just provides a 6° F rise in temperature
- Heat is insufficient in some cases
What our Testers Say:
This small aquarium heater struggles when the environment is really cold, and there is actually no thermostat control. Our verdict: something cheap and small, but not for expert aquarists.
