Top Smallest Aquarium Heaters for Nano Tank

Top Smallest Aquarium Heaters for Nano Tank

Nano tanks are relatively new in the aquarium market. Nano tanks come in quirky designs and are helpful in small house fish or display your coral collections. These are compact, portable, and stay in the corner of your house without taking up space. A considerable part of a tank ecosystem is perfect tank conditions. These conditions are the key to a lively collection of aquatic creatures.

The more significant challenge with the nano tanks is the small space. Nano tanks require nano equipment to keep your animals alive. Equipment such as filters, lights, and heaters are essential for fish, invertebrates, and coral. It is common among aquarists to let go of heaters in favor of other utilities due to lack of space in a nano tank. But, this proves dangerous to the creatures inhabiting the tank. Most sea creatures have specific temperature needs, and if the water is too hot or too cold, it could prove fatal to these creatures.

We have compiled a list of heaters that will fit perfectly in your nano tank without taking up too much space. These recommendations showcase a range of heaters suitable for tanks between 1 to 5 gallons. Through this guide, you will pick the right heater for your needs.

Types of small aquarium heaters:

You need heaters that can submerge into the water entirely for small-sized tanks such as nano tanks. These heaters are called submersible heaters. There are two different kinds of heaters for submersible heating options. Let us take a look at them.

1. Preset aquarium heaters

Preset aquarium heaters do not allow you the flexibility of changing the temperature. However, they come pre-adjusted, and all you have to do is attach the heater to your tank. Preset heaters are the proper size for nano tanks, and they work pretty well.

2. Adjustable aquarium heaters

Adjustable aquarium heaters are heaters that you can adjust and change according to your needs. These heaters let you decide the temperature at which you can keep your tank. These heaters are more accurate than preset heaters because they allow you to control the temperature. If something goes wrong with your fish and they do not adapt to the current temperature, you can always change the heater settings. The only problem with adjustable heaters is that they are difficult to find in smaller sizes. For nano tanks, where you have little space, a flexible heater will not fit – so you may have to consider the present one.

In our guide on small aquarium heaters, we have included some great suggestions for preset heaters that will do just fine for your tank!

5 Smallest Aquarium Heaters: Reviewed

Some of the best aquarium heaters for small tanks are as follows.

1. Cobalt Aquatics Adjustable Aquarium Heater

Compared to the other options on this list, the Cobalt Aquatics dual display submersible heater is expensive. However, this nano tank heater comes fully packed with amenities and an impressive design. The quality of the product and the extended warranty makes it worth the money. The company boasts of using a shatterproof plastic material, which guarantees long life. It has a flat design and can fit into a tank with little space.

Even though the temperature range is less, the heater allows you to adjust the temperature according to your needs. In addition, it has a ready thermostat, and you do not need to invest in a different one.

Another impressive feature about this heater is that this range is available in a variety of sizes, from 6 gallons up to 55 gallons.


  • Submersible, adjustable heater
  • Available sizes: 25W (upto 6 gallons), 50W (upto 12 gallons), 75W (upto 20 gallons), 100W (upto 29 gallons), 150W (upto 40 gallons), 200W (upto 55 gallons).
  • Style: Neo-Therm
  • Fully submersible
  • Reversible holster
  • Shatterproof
  • Dual display


  • 3-year warranty
  • Adjustable controls
  • Built-in thermostat
  • Compact design
  • Prevents from over-heating the tanks
  • Shatterproof materials
  • Available in many sizes


  • Not very affordable
  • Customers’ reports of suction cups becoming dysfunctional

2. Freesea Mini Aquarium Submersible Heater for Nano Tanks with Temperature Display

Freesea’s mini aquarium heater is uniquely-shaped. It is oval and comes with a digital display of the tank’s temperature. It is suitable for nano tanks because of its size and shape. Some great features that it comes with are automatic shut down once the desired temperature has been reached. Even though it is priced less, it comes with a one-year warranty, and the dial is big enough to see the digits from a distance.

One precaution you need to take is to be careful not to operate this heater outside of water because it is fully submersible. One pretty glaring con is that the device does not power off if the water evaporates from the tank. This may cause a fire hazard as it keeps operating even though there is no water around it.

The basic 50W version is perfect for tanks between three to twelve gallons.


  • Submersible, adjustable heater
  • Available sizes: 50W (up to 12 gallons), 75W (up to 20 gallons), 100W (up to 29 gallons)
  • Auto shut off to prevent over-heating
  • LED digital display
  • 5 feet cable
  • Cyclic button for temperature setting
  • Temperature range: 59 degrees F to 94 degrees F
  • 12-Month Warranty
  • 24-Hours Professional After-sales Service.


  • 12-month warranty
  • Reliable thermostat readings
  • In-built thermostat
  • Automatic shut off feature to prevent over-heating
  • External touch controls for temperature


  • The cord is not long enough for some tanks
  • It does not switch off when not surrounded by water
  • Not suitable for tanks as small as 1 gallon, or even 4 inches in size, due to excessive force of the heater

3. Hygger Submersible Heater for Aquariums

Hygger submersible heater is also oval-shaped and comes in handy for smaller-sized tanks. The company recommends that you use this heater in nano-tanks. Feature-wise it is the same as the Freesea model, but a glaring difference between the two is the shutoff feature when the heater is not submerged in water. In Hygger heaters, this is not a problem. Not only does the heater power off when it is not surrounded by water, but it also powers on again when it detects water. Hence, it is safer to use and does not pose any electrical threats.

The cage-like covering that it comes with also gives it a stylish look.


  • Submersible, adjustable heater
  • Available sizes: 50W (up to 6.5 gallons), 100W (up to 13 gallons)
  • Temperature range: 63 to 94 degrees F
  • Digital display
  • Automatic shutoff feature
  • Shuts off when the heater is out of water


  • Cost-effective option
  • Automatic shutoff prevents any electrical hazards
  • The heater shuts down once it reaches the desired temperature


  • No warranty available
  • The controller is not waterproof

4. Nicrew Preset Aquarium Heater for Mini Tanks

The Nicrew preset heater is easy to set up and can be used for tanks that only house one community and suit the 78 degrees F temperature. It is preset, so you do not have any temperature-changing liberties. The design is sleek, and you can also place the heater in different orientations.


  • Submersible, preset heater
  • Temperature range: 78 degrees F
  • Digital display
  • Automatic shutoff feature
  • Shuts off when the heater is out of water
  • External controller


  • Easy-to-use
  • LED Display
  • Not a safety hazard, due to the automatic shutdown feature
  • Different placement options are available


  • Customers complain of faults after using the heater for a few months
  • Not very customizable due to the preset temperature

5. Aqueon Preset Aquarium Heater

Aqueon is a trusted brand and has a foothold in the heater industry. Most Aqueon heaters are compact, well-built, and high-quality. This particular heater comes in one option: a 50 W heater. This size is perfect for up to 10-gallon tanks. Unfortunately, they come with a preset thermostat temperature of 78 degrees F that cannot be changed. This limits your options for what fish or invertebrates to stock in your tank.

You will need to buy a separate thermometer to check the temperature of your tank.


  • 50 W heater (up to 20 gallons)
  • Preset temperature: 78 degrees F
  • Shatterproof materials used in the construction
  • Safety shutoff
  • LED indicator light
  • Submersible heater


  • Cost-effective option
  • Automatic shutoff prevents any electrical hazards
  • The heater shuts down once it reaches the desired temperature
  • Shatterproof design
  • Different placement options


  • Not adjustable
  • No display to know the temperature
  • Need to buy a thermometer separately

Buying Guide: What to Look for In a Small Aquarium Heater?

Although there are multiple options to choose from for a small-sized aquarium heater, there are some things that you can check to narrow down your search.

1.   Thermostat

You need to check in all heaters whether they come with a thermostat. A common addition to heaters these days, thermostats are practical add-ons. How will you operate your heater without knowing what temperature your tank is currently at? The thermostat tells you when it’s time to change your water temperature and regulates the tank’s temperature. Instead of buying a thermostat separately, buy a heater that comes with a thermostat.

2.   Long-lasting use

Just like everything in your aquarium, your heater will not last forever. Unfortunately, this is the reality of heaters. They are electrical appliances, so they only last up to a specific time. Some heaters claim to last longer, but most develop some of the other flaws within a few years of using them. In this case, the best thing to do is to look for a heater that has a more extended warranty period. If it goes wrong within the warranty period, you can always get a replacement or fixed free of cost.

3.   Invest in an extra heater

If your tank is slightly bigger, or even if your regular heater stops working, you can keep another one as a backup. If one of your heaters suddenly goes wrong, then you cannot keep your tank without a heater until you can go and buy a new one. This is where an extra heater comes in handy.

4.   Material of the heater

Getting a good quality heater is key to making it last longer. Ensure that your heater is made of a strong material such as stainless steel, titanium, etc. Glass heaters are the original type of heaters but do not be afraid to experiment.

5.   Check your room temperature.

Depending on the place you live, your room temperature will vary. If you live in areas that get very cold during winters, you may want to go in for a heater that is recommended for larger tanks than yours. If it is warm at the place you live, then you may go the same sized heater or smaller.

6.   Decide between preset and adjustable heaters.

Preset heaters will not give you the liberty of changing your temperature at all. On the other hand, adjustable heaters will provide an option for temperature changes within a range. Depending on what fish and how many different species you plan on housing in the tank, you will need to decide the type of heater you want. If you have different types of fish, then it makes sense for you to go in for an adjustable heater. On the other hand, if you only plan on keeping one type of fish, then preset heaters will do the job.


Can you use a heater in a 3-gallon tank?

Yes, a heater is essential in a 3-gallon tank, even if it’s smaller than the others in size. Since a 3-gallon tank would be too small, use a submersible heater not to take up much space. An ideal heater wattage for a 3-gallon tank would be between 10 to 15 watts. Cobalt Aquatic Adjustable Heater is a good option for a 3-gallon heater.

Can you put a heater in a 5-gallon tank?

Any 5-gallon tank will require a heater because of the size and the fish you store. The minimum voltage you will need for the heater is 25 watts. However, we advise you to go for at least a 50-watt heater. Among our recommendations, one of the best 5-gallon tank heaters is the Aqueon Preset Submersible Aquarium Heater.

What size heater do I need for a 1-gallon tank?

While picking the right heart size, you need to follow the rule of thumb. Generally, you need to increase 5 watts for every gallon of water in the tank. For a tank as small as a 1-gallon tank, we recommend the Freesea submersible heater.

Wrapping Up

The brand’s reliability is the most significant thing to keep in mind while shopping for aquarium heaters for small tanks. Unfortunately, you can not guarantee that a heater will work well because it is expensive or more extensive. Our best recommendation is the Aqueon Preset Aquarium Heater. It comes in an all-inclusive kit and works well for nano tanks. Aqueon is a good brand and has many options to customize your heater.

Even though you have a heater, you will regularly check the temperature. Make it a habit to check the tank’s temperature at least once a day. Investing in a good heater will reduce most of your problems and keep your fish healthy for long.

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