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6 Best Small Aquarium Heater (Below 8 Inches) For Nano Tanks

Best Small Aquarium Heater

A tank heater is a piece of essential equipment for an aquarium. It will help you keep the fish tank water warm and stable, which can prevent your fish from getting diseases and make them live longer. 

Especially in winter, you need to use a heater to raise the water temperature in your tank so that your fish can enjoy a healthy life.

So undoubtedly, heaters are an essential part of any aquarium. But when it comes to small aquariums, it can be tough to find a heater that is both affordable and effective. 

That’s why I’ve put together this list of the six best small aquarium heaters. These heaters will perfectly fit in your nano tank and keep it at a comfortable temperature without breaking the bank. 

So, whether you’re just starting out with fishkeeping or you’re looking for an upgrade, check out my picks for the best small aquarium heater.

Top Pick
hygger 100W Mini Submersible Digital Display...
The Smallest
FREESEA 50W Mini Aquarium Heater Fish Tank...
The Cheapest
Tetra HT Submersible Aquarium Heater With...
hygger 100W Mini Submersible Digital Display...
FREESEA 50W Mini Aquarium Heater Fish Tank...
Tetra HT Submersible Aquarium Heater With...
$22.99
$18.99
$11.99
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6,646 Reviews
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Top Pick
hygger 100W Mini Submersible Digital Display...
hygger 100W Mini Submersible Digital Display...
$22.99
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-
The Smallest
FREESEA 50W Mini Aquarium Heater Fish Tank...
FREESEA 50W Mini Aquarium Heater Fish Tank...
$18.99
6,646 Reviews
The Cheapest
Tetra HT Submersible Aquarium Heater With...
Tetra HT Submersible Aquarium Heater With...
$11.99
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How To Choose The Right Size Of Aquarium Heater

The power of an aquarium heater is measured in watts (W). For instance, a 20-watt unit will heat up your aquarium twice as fast as a 10-watt one. So if you have a big tank, get yourself some higher-powered gear.

How To Choose The Right Size Of Aquarium Heater

The rule of thumb is that you would need 2.5 to 5 watts for one gallon, which means if your tank holds 10 gallons and your heater has a power rating higher than 25W, then it will efficiently heat up the water in the tank without too much trouble! 

However, there’s more than just size when considering how well these things work; environmental factors such as ambient temperature also come into play here.

Small Heaters Types

There are two main categories in the world of small aquarium heaters – preset and adjustable. 

A small fish tank heater will be either a preset type or one that has an adjustable temperature controller.

Preset Aquarium Heaters

These models typically have an “always-on” design and will not turn off until the temperature reaches 78 degrees Fahrenheit (26 Celsius).

One of the best things about preset heaters is their size. They don’t require a thermostat, so manufacturers can create some unbelievably slim and small aquarium heater models!

But preset heaters are not so accurate in maintaining fish tank temperature. An added temperature controller can help regulate the precise temperature and provide safety features.

You can not adjust them – you are at the grace of your heating system. You do not have to go far to find horror stories of preset heaters accidentally killing fish.

As you know, the fish tank water temperature vastly depends on the environment temperature. So on a hot summer day, preset heaters will likewise enhance the temperature of your tank, nonstop – which might be too hot for your fish.

If you have a tiny aquarium with less than 3 gallons of water, a small preset heater will give you more space in the tank.

Adjustable Aquarium Heaters

You can set the water temperature within a defined range with an adjustable heater. You can regulate your water temperature with such a heater, which has the added benefit of keeping the water temperature as your fish need.

These usually come in a bit larger sizes than those of preset heaters but offer more features like shutting off when it reaches your desired temperature level or adjusting its operation based on how cold things get outside!

The ideal temperature for your fish tank is between 66 – 96 degrees Fahrenheit. Still, many people want colder or warmer water as they might have particular kinds of fish species with different needs. This type of heater allows you to set the desired range, and it will maintain that level with precise control!

Also Read: How Do I Know If My Aquarium Heater Is Working

Best Small Aquarium Heater: 6 Top Picks Reviewed 

FREESEA Mini Aquarium Heater 

FREESEA Mini Aquarium Heater 
Sale
FREESEA 50W Mini Aquarium Heater Fish Tank...
6,646 Reviews
FREESEA 50W Mini Aquarium Heater Fish Tank...
  • ★ Temperature range: 59°F~94°F, display Fahrenheit °F, this heater is designed for1~10 gallons tank. Upgrade...
  • ★ Automatic constant temperature function, when water temperature reaches to specified temperature value, heater will...
  • ★ Touch button, cyclic adjust temperature , easy to use and Safety.
  • ★【Note】:this heater is 100% submersible use only, during its heating time, heater must be 100% submerged into the...
  • ★【SATISFACTION GUARANTEED】Gain the confidence to go hard with us! Our Aquarium Heater is built with durability in...

FREESEA Mini Aquarium Heater is a new product of FREESEA. It can automatically control the temperature of your aquarium so that you do not need to worry about the temperature difference between winter and summer. 

It can make your fish feel comfortable. Its unique design makes its heating area more extensive than other heaters, which will make the water temperature more stable. 

You’ll be surprised at how stylish this small heater looks in your nano tank! The longest part of these heaters is 3.5 inches long, which means you can fit these bad boys perfectly in your nano tank.

It has a large LCD screen to clearly show its working state and parameters. In addition, it features auto shutting off once it reaches this desired level of temperature!

This aquarium heater may not be a good fit for tiny tanks such as the 2-gallon one, as it could prove too powerful!


Pros

  • 1 Year Warranty.
  • Small and compact with just 3.5 inches in length.
  • Accurate readings on the LED display.
  • Affordable.
  • Reliable thermostat to maintain a precise temperature.
  • Adjustable temperature control.
  • The temperature controller is outside of the water – no wet hands.
  • Stylish in design and visually appealing.

Cons

  • The power cord is short.
  • No automatic turn-off feature when it is out of the water.

Hygger Submersible Heater 

Hygger Submersible Heater
hygger 100W Mini Submersible Digital Display...
  • 🐠【Compact Small Heater】110-120V/60HZ oval shape design little aquarium heater, fast heating for small fish tank....
  • 🐠【External Controller】easy to set the temp on the controller, only show farenheit temp, you can set the temp...
  • 🐠【Digital Display】with led display on the midle of the heater front side, when the fish tank heater is heating,...
  • 🐠【Reliable Thermostat】this an automatic aquarium thermostat, after finishing the temp setting, you can be...
  • 🐠【Shut off When Out of Water】please note that this a fully submersible aquarium heater for fresh water and...

The Hygger Submersible Heater is a small, compact, and powerful submersible aquarium heater with memory function if power failure happens. Whereas, with its built-in thermometer, you can monitor water temperature in the tank!

The protective plastic cage gives it a cool look. The temperature controller is outside the tank on the cord, which is pretty convenient. 

The suction cups seem reliable and haven’t moved since I set them. Two strong suction cups can be placed anywhere in the tank and replaced quickly. 

What else I like about Hygger’s heater is that it has its own protection to stop working when the water isn’t fully submerged. This type of safety feature isn’t usually found at this price point, so kudos to them for providing it!

I think the Hygger’s Submersible Aquarium Heater is a great addition to small tanks with water volume between 1 and 13 gallons. It’s affordable, compact, and allows you plenty of space for your fish!


Pros

  • 50-watt and 100-watt are both 4.5 inches in length.
  • Very affordable and reliable.
  • Auto shut-off feature when the preset temperature is reached.
  • Auto shut-off when the heater is below the water level.
  • It will also automatically shut off if the temperature is above 95 F.

Cons

  • No warranty is provided.
  • Sometimes the LED display may show wrong reading by 1 F.

Tetra HT Submersible Heater 

Tetra HT Submersible Heater
Sale
Tetra HT Submersible Aquarium Heater With...
  • All Tetra HT heaters have indicator lights to let you know when the heater is on. It will be red when heating and green...
  • The HT10 uses a built in electronic theromstat to automatically maintain water at 78° F which is ideal for most...
  • Ideal for aquariums between 2 to 10 gallons with hoods or glass canopies
  • The HT heater is fully submersbile and can be installed vertically or horizontally. It's small footprint makes it easy...
  • Please read all label information upon delivery. DO NOT plug heater into an electrical outlet until it is placed inside...

The Tetra HT10 submersible heater is a 5.25″ long compact and durable heater that can be used with aquariums up to 10 gallons. This handy little device will help keep your fish happy.

The Tetra HT Submersible Aquarium Heater is perfect for small to medium fish tanks. It features an automatic thermostat that keeps water at 78° F, suitable for most tropical species of freshwater creatures!

Make sure you purchase one made for whatever tank size is being heated. The wrong size can cause underheating! Also, you should cover your tank with a hood or glass canopy to contain the heat inside the aquarium. 

The red light will come on when the heater is heating up and turn off when the proper water temperature is reached, and the green light comes on. 

The Tetra HT Submersible Heater is a fully submersible heater for aquariums. This heater can be installed vertically or horizontally, and its small footprint makes it easy to conceal behind plants or other décors. 


Pros

  • Reliable heater for up to 10-gallon tanks.
  • Very affordable.
  • Easy to use for new users.
  • The Red and Green indicator light is convenient.
  • It can be installed vertically or horizontally.

Cons

  • It is not an adjustable heater.
  • No dry run protection feature.

Hydor Slim Heater For Aquariums

Hydor Slim Heater For Aquariums
Sale
Hydor 15w Slim Heater for Bettas and Aquariums, 5...
1,627 Reviews
Hydor 15w Slim Heater for Bettas and Aquariums, 5...
  • Helps guarantee your fish a healthy life by promoting the ideal water temperature
  • Plug and play
  • No temperature to set
  • Can be positioned under gravel
  • No glass components

The Hydor Slim Heater is a plug-and-play aquarium heater that can be positioned under gravel. The Slim Heater is a safe and economical choice for your fish tank.  

The 15-watt heater is only 6.5 inches long and perfect for aquariums between 5 – 10 gallons in size.

It has no glass components, so there is no risk of sudden damage if it accidentally falls off your hands. 

Hydor’s Slim Heaters will help you keep your fish healthy by promoting the ideal water temperature. It has an adjustable temperature dial to ensure your fish have the perfect water temperature. 

 It is specially designed with an innovative positive thermal coefficient element, which ensures that it warms up to 5-10 degrees warmer than room temperature! 


Pros

  • Convenient for fish bowls and Betta fish tanks.
  • Very effortless to use, only plug-and-play.
  • This heater can be positioned under-gravel also.
  • No glass component, so not fragile.

Cons

  • Minimal power, maximum of 15 watts.
  • Not suitable for freezing winters.
  • No temperature adjustment option.

Aqueon Preset Aquarium Heater 

Aqueon Preset Heater For Aquariums
Aqueon Preset Aquarium Fish Tank Heater 100 Watts
  • Preset to 78°, accurate to +/- 1°
  • No adjustment required
  • Shatter resistant
  • Fully submersible, auto shut-off when overheats, resets when cools down
  • LED light turns on when aquarium water is being heated

When it comes to fish tanks, Aqueon has everything. With innovative products and prices that can’t be beaten – they are one of the best places for any aquarium enthusiast! 

With a preset temperature of 78° Fahrenheit (25 Celsius), this aquarium heater provides perfect conditions for most tropical fish species and other animals like turtles or invertebrates. 

This product features state-of-art technology with safety measures built into every design, ensuring no worries about overheating. In addition, it has an easy-to-use thermostat that shuts off at higher temperatures, so your pets stay happy in their home!

The Aqueon Aquarium Heater is an excellent choice for any small aquarium with a black background. This heater will fit in perfectly and be almost invisible, which means you can enjoy your fish without worrying about the aquarium’s look being unpleasant! 

The price tag also makes this product very affordable – perfect if cost efficiency matters at all times (which it does)!


Pros

  • Comes with a 1-Year warranty.
  • Affordable aquarium heater.
  • Automatic shut-off feature when the preset temperature is reached.
  • Built with shatterproof material.
  • You can place it either horizontally or vertically in your tank.

Cons

  • Non-adjustable temperature.
  • No indication of the current temperature in the tank.

Hitop Adjustable Aquarium Heater 

Hitop Adjustable Aquarium Heater
Hitop 50W/100W/300W Adjustable Aquarium Heater,...
  • Explosion Proof: 2mm thickened explosion proof glass, 33% thicker than the normal, safer for both human and animals.
  • Application: 50W water heater is suitable for 5 – 15 gallon tank, also suitable for both saltwater and freshwater.
  • Accurate Temperature: Temperatures from 68°F to 93°F (20°C - 34°C), come with a thermometer sticker, convenient to...
  • Long Service Life: Adopt 8-slot multi-branched heating wire ceramic frame, shorter length, 7.8*1*1 in(20*2.5*2.5 cm),...
  • Complete Accessories and Warranty: Except for thermometer, also equipped with 3 suction cups, one for replacement, and...

The Hitop Adjustable Aquarium Heater has three different sizes, and the 50W adjustable heater is 7.8″ long (longest in the list). It can be used in 5-20 gallon fish tanks and saltwater/freshwater tanks. 

This heater is simple, beautiful in appearance, and will not destroy your fish tank landscape. 

Hitop Adjustable Aquarium Heater is a high-quality & accurate heater for your aquarium. The explosion-proof glass, which is 33% thicker than usual, makes it safer for humans and animals.

It has an automatic shut-off feature, so there are no worries about overheating.

It has a thermometer sticker and is convenient to detect the water temperature without another pay. In addition, the 8-slot multi-branched heating wire ceramic frame can save more space for your fish and better heat dissipation, which can prolong the service life of this aquarium heater.

It comes with suction cups (including one extra for replacement), so you can place it anywhere you want on the glass of your aquarium. However, the heating element must be fully submerged in water to avoid burning up and damaging the unit!


Pros

  • It is safe, reliable, and explosion-proof.
  • Good in maintaining temperature.
  • Suitable for freshwater and saltwater.
  • Simple and beautiful in appearance.
  • Automatic shut off when the preset temperature is reached.

Cons

  • This heater is relatively larger – almost 8 inches!

Small Aquarium Heaters: A Few Tips

Best Small Aquarium Heater Tips

Get One Back Up Heater

You can never be too careful with aquariums. So it’s always a good idea to have one backup heater just in case your main unit malfunctions or stops working altogether, and you want it so that when this does happen, there will still probably not be any problems!

If you want to keep your fish healthy and happy, the water must stay at a consistent temperature. A backup heater will also ensure no fluctuation occurs when other unit struggles.

Get More Watt If The Average Temperature Is Low In Your Home

Heaters vary in power and size, so it is vital to research what wattage you need for your aquarium. For a 10 gallon tank, I recommend at least 50 Watts. 

If there’s no cold winter, a 50-watt heater will do just fine in a 15-gallon tank also. But if it gets freezing, get at least that much power to keep your fish warm and comfortable!

When winter comes, make sure you have an effective way to keep your fish warm. An undersized aquarium heater is not capable of heating an entire tank, and fish may get sick if it’s too cold outside!

The Heater Should Be Realistically Durable

While it may seem like the dream of owning an aquarium heater is to have one that lasts forever, this reality doesn’t unfold as we hope.

The best indicator for durability in fish tank heaters comes from their provided warranty period – how long they can take care of your needs in case of any significant issues with functionality.

The warranty on your new small heater will ensure that you have peace of mind, knowing the company is confident in its product. Remember that more extended warranties mean a lower risk for failure, so make sure to buy one with at least 1 year worth!

Final Words

When it comes to small aquariums, many factors can affect the temperature. And with so many heaters on the market, it’s not always easy to find one for your tank size. 

To help you out, I’ve compiled a list of six top-rated small aquarium heaters above and reviewed them with pros and cons! Hopefully, it helped you. 

If you want more information about any of these products or if you have anything else to ask me, please leave a comment below this article, and I’ll get back to you as soon as possible. Thanks again for reading my blog post today.

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