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As fish cannot regulate their own temperature, it’s up to you to make sure their water is not too warm or cool. This is where an aquarium heater comes in.
A heater keeps the water in your fish tank at a consistent temperature to prevent your inhabitants from becoming too hot or cold. For nano aquariums in particular, heaters can be an issue as they take up a fair amount of space.
As nano tanks are already pretty compact, you obviously want a heater that’s small enough to fit inside your aquarium. To make your search easier, I’ve looked at a range of heaters that are suitable for nano tanks.
After considering all the options our top 3 picks for the best aquarium heaters were…
Review Summary
Here’s the summary of the top 3 best small aquarium heaters from our list…
Hygger Submersible Aquarium Heater
This small heater can warm your tank from 75°F to 91°F, which is adequate for most species of fish. You can also monitor the temperature of your aquarium using the built-in thermometer.
Best All-Rounder: Hygger Submersible Aquarium Heater
Out of all the heaters I’ve looked at, this one is my overall recommendation for a small aquarium.
With a wattage of 100W, Hygger’s submersible heater is ideal for small aquariums up to 30 gallons. It has adjustable temperature controls that can be accessed via a remote, as well as safety features like a shield guard.
Tetra HT Submersible Aquarium Heater With Electronic Thermostat
This small heater has a built-in electronic thermostat which automatically maintains the temperature of your aquarium at 78°F. This should be sufficient for most tropical fish.
Best on a Budget: Tetra HT Submersible Aquarium Heater With Electronic Thermostat
This small aquarium heater is a solid choice for aquarists on a budget due to its affordability.
If you’re looking for an inexpensive small aquarium heater, then Tetra’s HT 50-watt heater is worth considering. Its temperature is preset to 78°F, which makes it suitable for most species of tropical fish.
It also has a small footprint to make it easy to conceal, and an indicator light for added convenience.
It’s 50 watts and made of shock-resistant and shatterproof laboratory-grade glass, which allows for even heat distribution to make sure your nano aquarium stays at a consistent temperature.
Editor’s Choice: Eheim Jager Aquarium Heater
This nano aquarium heater is my personal favorite for a small aquarium. It’s a little pricier than the other small tank heaters, but has a lot of impressive features.
Made from shock-resistant and shatterproof glass, Eheim Jäger heaters are one of the best to use in nano aquariums. They have adjustable temperature controls, safety features, and a compact design.
What Are Aquarium Heaters?
Aquarium heaters are used in fish tanks to increase or maintain the water temperature. Freshwater and marine fish require a heater in their aquarium as they originate from warmer climates.
What Size Heater Do I Need for a Nano Aquarium?
Aquariums under 30 gallons are considered nano, but there’s no one-size-fits-all small aquarium size heater. The volume of your aquarium is important for calculating a suitable heater with an appropriate wattage. You can use a single heater or two smaller aquarium heaters. In general, you’ll need 3-5 watts per gallon of water.
A 55-gallon tank setup might, naturally, call for a 55-gallon fish tank heater.
RECOMMENDATION
As a rule, you need to use between 2.5 and 5 watts per gallon of water. For example, if your tank is 5 gallons, then you’ll require a heater with a wattage of 12.5W to 20W. In contrast, 300W aquarium heaters are suitable for tanks up to 60 gallons.
Types of Aquarium Heaters
There are a few different types of aquarium heaters you can use in your small tank. While there are some variations between each type, the best one for you mostly depends on personal preference and the species of fish you own.
Hanging/Immersible Heater
Hanging heaters go over the top of your aquarium. The heating component of the unit is placed inside your tank to raise the water temperature. With this type of heater, you’ll need an opening in your tank hood.
NOTE
Hanging heaters are common in starter tanks or tropical fish aquariums targeted for beginners. They’re not as effective as some other types of heaters, but they’re adequate for a basic small aquarium.
Substrate Heater
This type of heater is normally used with another heater. They consist of a long heating wire that is affixed to the bottom of your tank. A substrate heater is a good option for planted small aquariums as they increase fluid movement in the substrate and promote plant growth.
Unfortunately, substrate heaters can be a bit pricey as they are not very common.
Submersible Heater
Submersible heaters are placed directly and fully submerged in your tank water, normally next to your filter. They are wrapped in a strong plastic or glass tube, with a coiled heating element inside.
Submersible heaters that are made out of glass are at risk of shattering if they overheat, so you need to monitor the unit closely. A heater can overheat or shatter if it’s removed from your tank water without being turned off first.
Inline Heater
An inline heater is put on the outflow line of your filter so it can heat the water that is pumped back into your small aquarium. This type of heater is normally used in fish tanks with large aggressive species and can be a bit pricey.
Filter Heater
Some filters come with a built-in heater. This allows the heater to instantly warm up the water that the filter deposits back into your nano aquarium. Filter heaters can be found in some types of canister or power filters.
Do You Leave the Aquarium Heater on in a Fish Tank?
A fish tank heater needs to be kept on at all times in order to effectively maintain the temperature of your fish tank water. The only time you should turn off your heater is before water changes or tank maintenance.
How Long Does it Take for a Heater to Heat a Fish Tank?
The length of time it takes for a heater to warm up a tank depends on the wattage of the unit, the volume of the aquarium, and the temperature of the room. A heater can take anywhere from two hours to two days before the target temperature is reached in your tank water.
Can Fish Get Burned By a Heater?
Although rare, fish can get burned by a heater. If the unit overheats or your fish get trapped against it, then your fish are at risk of being burned. To ensure this doesn’t happen, consider using a shield guard on your device. You should also monitor the temperature of your tank water regularly using a thermometer.
Do You Need a Heater with a Temperature Control and Thermostat?
While not essential, it’s a good idea to use a heater with a temperature control. Being able to adjust the temperature of your device is handy as certain species of fish require a higher or lower water temperature than what is usually the standard on pre-set heaters.
NOTE
A thermostat allows you to check the temperature of your tank water, which you should monitor regularly. Some heaters come with thermostats for added convenience, but it’s not a make or break factor if your device doesn’t include one. Aquarium thermostats can be bought separately and are typically inexpensive.
Nano Aquarium Heaters Reviews
Here are the full reviews of all the best small aquarium heaters in our list…
Hygger Submersible Aquarium Heater
This small heater can warm your tank from 75°F to 91°F, which is adequate for most species of fish. You can also monitor the temperature of your aquarium using the built-in thermometer.
Best All-Rounder: Hygger Submersible Aquarium Heater
With a wattage of 100W, the Hygger aquarium heater is suitable for small tanks up to 30 gallons. I think this adjustable aquarium heater is a solid choice for any nano tank as it’s reliable and has a range of features.
It can even work as a 30-gallon fish tank heater if need be.
Once the desired temperature has been reached, the unit automatically switches off to prevent overheating…
It has adjustable temperature controls that can be accessed using an external remote, which is handy. Once the desired temperature has been reached, the unit automatically switches off to prevent overheating.
Additionally, the device includes a shield guard and will shut off if a fault occurs in the device to protect your tank’s inhabitants.
monitor the temperature of your aquarium using the built-in thermometer…
The heater can warm your tank from 75°F to 91°F, which is adequate for most species of fish. You can also monitor the temperature of your aquarium using the built-in thermometer.
Another great aspect of the Hygger unit is its compact design. This makes it easy to hide behind plants or other decors.
Despite its positives, the unit does have a couple of drawbacks. The adjustable temperature controls can be a little unreliable and the heater itself can stop working prematurely.
Specs
- Size: 7.5” x 8.5” x 10.6”
- Weight: 14.1 oz
- Wattage: 100W
- Temperature Range: 75°F-91°F
Pros
- Includes a shield guard
- Adjustable temperature controls
- Safety features
- Built-in thermometer
Cons
- Temperature controls can be unreliable
- Can have a short lifespan
Tetra HT Submersible Aquarium Heater With Electronic Thermostat
This heater has a built-in electronic thermostat which automatically maintains the temperature of your aquarium at 78°F. This should be sufficient for most tropical fish.
Best on a Budget: Tetra HT Submersible Aquarium Heater With Electronic Thermostat
This aquarium heater is an affordable but adequate option for small tanks up to 10 gallons as it’s 50 watts, making it a top choice for 10-gallon aquarium heaters. It’s easy to set up and can be placed either horizontally or vertically using the provided suction cups.
has a built-in electronic thermostat which automatically maintains the temperature of your aquarium…
This small aquarium heater has a built-in electronic thermostat which automatically maintains the temperature of your aquarium at 78°F. This should be sufficient for most tropical fish.
Light Indicator Feature
For convenience, the aquarium heater has an indicator light that lets you know when the unit is turned on. The light will be red when the unit is actively heating and green when the correct temperature has been reached.
Its small footprint makes it easy to hide behind plants or other decors in your tank…
My favorite aspect of this small tank heater is its compact and sleek design. Its small footprint makes it easy to hide behind plants or other decors in your small tank.
However, there are a few issues with Tetra HT aquarium heaters. For one, the unit can struggle to maintain the water temperature of your aquarium at 78°F. As the unit does not come with adjustable temperature controls, this can be problematic.
Secondly, the indicator light on the aquarium heater can also be unreliable or stop working altogether. And lastly, the lifespan of the heater is fairly short, so it might need to be replaced after a short period of time.
Specs
- Size: 5.2” x 1.6” x 3.5”
- Weight: 7.2 oz
- Wattage: 50 W
- Temperature Range: 78°F
Pros
- Built-in thermostat
- Indicator light
- Compact design
Cons
- Can struggle to maintain temperature of tank
- Indicator light can be unreliable
- Short lifespan
It’s 50 watts and made of shock-resistant and shatterproof laboratory-grade glass, which allows for even heat distribution to make sure your nano aquarium stays at a consistent temperature.
Editor’s Choice: Eheim Jager Aquarium Heater
One of my personal favorite small aquarium heaters to use in nano aquariums is the Eheim submersible heater. It’s 50 watts and made of shock-resistant and shatterproof laboratory-grade glass. The latter allows for even heat distribution to make sure your nano aquarium stays at a consistent temperature.
It’s a great choice as a 20-gallon fish tank heater. Some nano tanks will be in the 20-30 gallon range.
made of shock-resistant and shatterproof laboratory-grade glass…
To make installation easy, the Eheim heater for nano aquariums is easy to set up as it comes with a mounting bracket and suction cups.
Wide Range of Temperature
You can change the temperature of this eheim heater from 65°F to 93°F, which is a wider range than most other aquarium heaters designed for nano aquariums. For added safety, the device will automatically shut down when removed from your aquarium water. I really like this feature as it’s easy to forget to switch off your heater before performing water changes or aquarium maintenance.
I also appreciate the unit’s light indicator that lets you know when the device is on or off. This allows you to clearly see when the heater is working or if there is a possible fault.
However, there are a couple of issues with this heater. The adjustable temperature controls can be a little unreliable and difficult to use. The unit can also lose effectiveness over time, which can affect its ability to heat up your small aquarium.
Specs
- Size: 1.4” x 9.6”
- Weight: 8.2 oz
- Wattage: 50W
- Temperature Range: 65°F-93°F
Pros
- Made from shatterproof and shock-resistant glass
- Can be set to a variety of temperatures
- Safety features
- Indicator light
Cons
- Adjustable temperature controls can be unreliable and hard to use
- Can lose heating efficiency over time
YukiHalu Small Submersible Aquarium Heater
The unit has a sleek design and can be placed using the included suction cups.
YukiHalu Small Submersible Aquarium Heater
This small fish tank heater is 25 watts, so it’s suitable for nano freshwater and saltwater setups. It has a digital temperature display, a temperature control button, and a built-in temperature sensor. All of these work to keep your nano tank at the right level of warmth.
this YukiHalu heater has a low energy consumption which is great for saving on your electricity bills…
This heater has a sleek, compact design and can be placed using the included suction cups. Compared to some other small or nano aquarium heaters, this Aquatop heater has a low energy consumption which is great for saving on your electricity bills.
Unlike some other nano aquarium heaters, this one from Aquatop has adjustable temperature controls that range from 64°F to 93°F. This is handy as it allows you to lower or increase the warmth of your tank for specific species of fish.
However, this Aquastop heater does have a couple of drawbacks. The adjustable temperature controls can sometimes be a little unreliable especially if you have a big tank.
Specs
- Size: 4.3 x 0.98 x 0.98 inches
- Weight: 7.83 oz
- Wattage: 25W
- Temperature Range: 64°F-93°F
Pros
- Digital temperature display
- Adjustable temperature controls
- Compact design
Cons
- Adjustable temperature controls can be a bit unreliable
Hydor Submersible Glass Aquarium Heating Unit
It has an adjustable temperature dial, when the desired temperature of your aquarium has been reached, the unit automatically turns off to prevent overheating.
Hydor Submersible Glass Aquarium Heating Unit
This 25-watt submersible heating device from Hydor is another ideal choice for a nano aquarium. It’s made from shatterproof and shock-resistant glass, and can be placed either vertically or horizontally.
made from shatterproof and shock-resistant glass…
It has an adjustable temperature dial, with the lowest setting being around 67°F and the highest being around 90°F. When the desired temperature of your aquarium has been reached, the unit automatically turns off to prevent overheating.
One of the main downsides of this heater is its stiff dial, which can make adjusting the temperature of the unit a little difficult. Additionally, the device can sometimes struggle heating your aquarium to your selected temperature.
Specs
- Size: 3.5” x 2” x 10”
- Weight: 8 oz
- Wattage: 25W
- Temperature Range: 67°F-90°F
Pros
- Adjustable temperature controls
- Made from shatterproof glass
- Automatically turns off when desired temperature has been met
Cons
- Temperature dial can be a bit stiff and unreliable
Summary
Let’s take a quick look at all our top picks…
Best All-Rounder
Out of all the nano aquarium heaters I’ve looked at, I think the best one to use in nano aquariums is the Hygger Submersible Heater.
With a wattage of 100W, this heater is suitable for small tanks up to 20 gallons. I think this heater is a solid choice for any nano aquarium as it’s reliable and has a range of features.
Adjustable Temperature
My favorite aspect is its adjustable temperature controls that can be accessed via an external remote. This allows you to make changes to the device without getting your hands wet.
I also like that the device comes with safety features, such as turning off automatically when the desired water temperature has been reached. This, alongside the included shield guard, helps protect your fish. However, the adjustable temperature controls and the unit itself can stop working over time.
My other recommendations for small aquarium heaters are the Tetra HT Submersible Aquarium Heaters and Eheim Jager Aquarium Heaters. Both are good selections for your aquarium, but the former is a more affordable option.
Best on a Budget
It has a small footprint to make it easy to conceal, as well as an indicator light to let you know when the device is actively heating or has reached your desired temperature.
Unfortunately, the unit is preset to 78°F and cannot be adjusted. It can also be a bit unreliable and has a fairly short lifespan.
Editor’s Choice
Eheim’s submersible heater is a little pricier than the other small aquarium heaters, but for good reason. It’s made from shock-resistant and shatterproof glass, is easy to set up, and can be adjusted to a wide range of temperatures.
It also automatically turns off when you remove it from your aquarium, which is handy for if you forget to turn off the unit before performing fish tank maintenance.
The only downside of the device is its unreliability. The adjustable temperature controls can be hard to use, while the heating element inside the unit can lose its efficiency over time.
