5 Best Filters for Small Fish Tanks – Up to 5 Gallons

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If you’re a new aquarium enthusiast, you might be wondering which water filter is best for a small fish tank. After all, a filter is an essential asset you need to buy before you fill the aquarium with lots of fish.

In this article I will tell you about the 5 best water filters that you can find online. Any of these 5 devices are suitable for small fish tanks that contain up to 5 gallons of water.

But before I talk about each product in separate, you should be aware of the type of filter that is best for such aquariums. So, let’s cover that first.

Best Filter for 5-Gallon Nano Aquariums

There are multiple types of filters that do the same thing: clean the water inside the fish tank. These are the different types of aquarium filters on the market that you can choose from.

  1. Hang on back filter
  2. Canister filter
  3. Interior filter
  4. Sponge filter

So, how do you know which type is best for a small fish tank? Let me tell you exactly!

A canister filter is usually used by medium-sized and big fish tanks that have a relatively larger capacity. You don’t need such a device for a 5-gallon aquarium.

On the other hand, an interior filter could be a good choice, as well as a sponge filter. But if we compare those to a hang on back (HOB) filter, they lack in terms of performance. So, the best choice would be a HOB filter.

A modern HOB filter can do 3 types of water filtration, that is expected from such a device: mechanical, chemical and biological filtration. This is probably the main reason why a HOB filter is better, than the other 2 types mentioned above.

But how do you know which hang on back filter is best for a 5-gallon fish tank? You’ll find out in no-time, because we’re moving on to talk about the 5 best filters for a small aquarium.

No matter which one you choose in the end, you can find it on Amazon, and purchase it from there.

1. Aqua Clear Fish Tanks Filter

This is our first item on the list. The Aqua Clear filter is a hang on back filter that comes in multiple different version that work with different-sized aquarium. For a small 5-gallon tank, you should look at the first version, the Aqua Clear 20.

This product works with aquariums that have at least 5 gallons of water inside them. This is great news, because this way, you can be sure it will easily stand up to your requirements. What does it do?

The filter includes a 3-stage filtration system: mechanical, biological and chemical. It’s worth noticing, that a re-filtration system is also put in place, that ensures a better contact time with the filter media that will clean the water from solid debris.

The pump used by the device is an energy efficient one, which means that it will lower the functioning and maintenance costs quite a bit.

Also, they include in the package biological filter media as well. Not all devices come with these in the standard package, but this one does. You get an AquaClear Foam, Cycle Guard and Activated Carbon with BioMax for a continuous bio-filtration system.

It’s worth mentioning that a 2-year warranty is also included. So, if anything may break inside the device, you just send it back, and they will take care of the issue.


2. AZOO Aquarium Mignon Filter 60

The second device on the list is the AZOO hang on back filter. If you compare this device with the previous one, you’ll find that they’re quite similar, both being HOB filters.

A great advantage that comes with this device is the small and compact build. After all, for a small aquarium, that is at most 5-gallon in capacity, you don’t need a huge filter. Such a device could ruin the whole look of your fish tank.

Luckily, this filter is quite small, and does what it claims. It cleans the water in all 3 ways that I already mentioned above. But there’s another huge benefit that comes with this item: it’s very silent.

Many people have their aquarium placed in silent rooms, like the office, or the bedroom. If that’s the case with you, a silent filter is what you probably want. You almost won’t notice that the AZOO is working, it’s that silent.

This filter is best suited for aquariums that have a capacity of 3 and a half gallons. So, it fits in the area we’re talking about. If you have a fish tank with this volume, the AZOO will easily do its best to filter the water. You shouldn’t be disappointed by its performance.


3. Aquapapa Corner Filter XY-2008

The Aquapapa filter is a little different from the previous 2 devices mentioned above. As you can see from its title, this device is a corner filter, which means that you have to put it inside the aquarium.

How does it work? It’s quite simple actually. The water is drawn inside the filter through a tube, and it is pumped through the filter media inside the device. When the water is filtered, it exits through an opening at the top of the device. The dirt and other debris stay in the filter, usually at its bottom.

This device is a multi-layer sponge filter, that will work just like I described above. The filter combines biochemical filtration with physical (mechanical) filtration, that results in better oxygen solubility.

The bottom layer of filter media (biological) is supporting the colonization of beneficial bacteria that consume the ammonia and nitrates from the water. This is very important, because a surplus of these substances can negatively affect your fish. Some breeds can even die from over-exposure to these particles.

Also, the filter is very easy to maintain. Just pick up the top, and take out the mechanical media. You rinse it with clean water, until it’s clean, then you place it back inside. However, when the media (biochemical and mechanical) becomes too old, you’ll have to replace them both, which is simple as well.


4. Upettools Aquarium Filter

This filter is also a sponge filter that sits inside the fish tank. It was crafted to protect your smaller fish, to not get sucked inside the filter, since it sits inside the aquarium.

It includes a mechanical and biological filtering system that does its job perfectly. The mechanical media will capture all the solid debris floating around in the tank, while the biological media is cleaning the water using the bacteria colonies inside them.

The device comes with 2 containers for bio-media. The media is already inside both containers, so you don’t have to do anything when setting it up. This media is made up of ceramic material that contains all the bacteria colonies used for bio-filtration.

Upettools is suitable for aquariums up to 20 gallons of water inside them. So, a small fish tank that’s at most 5-gallon big will pose no problem for this device. You’ll have a crystal clean water, properly oxygenated.


5. Huijukon Air Pump Double Sponge Filter

This sponge filter is the last on our list today. However, that doesn’t mean it’s worse in any way than the previous candidates. What does it do to clean your water environment?

First, you can notice it’s a sponge filter, like the previous item. So, it comes with great mechanical filter media to capture all the solid debris floating around in the tank.

But the sponge also contains bacteria colonies inside that will eat up the ammonia and nitrates from the water. So, the sponge is a 2 in 1 mechanical and biological filter, all at once.

Any small fish is protected against potential harm, because it won’t get sucked into the device accidentally. The bacteria inside the sponge will also contribute to the well-being of your aquarium life.

The filter is very easy to install. Just stick it to the wall of your aquarium, and squeeze the sponges in aquarium water. Also, make sure the end of the tube is outside the tank. That’s all you need to do.



In this article, you had the opportunity to learn about the 5 best water filters for small aquariums. Any of the 5 items I talked about can do a great job in your aquarium.

However, keep something in mind: if you choose a sponge filter, you also need to buy an air pump. This way, they will work together to provide an environment suitable for your fish. Don’t forget about this!

A great air pump, that works with any of the sponge filters from above is the Tetra Whisper air pump on Amazon. It comes in 4 different versions, but the one you need is the smallest version that is recommended for up to 10 gallons of water.

In the end, the choice is yours to make. No matter which device you go with, they can all to a great job cleaning your water for a long time. But don’t forget to do some maintenance work, to keep up the performance.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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