5 Best Filters for Small 5 Gallon Fish Tanks


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Small or large, any aquarium will benefit from a filter system that adds an extra layer of protection when it comes to water cleanliness and chemical stability.

A filter is especially important if you’re a beginner with a small fish tank because these tanks are much more unstable when it comes to water parameter issues.

In today’s article I’m going to focus on small fish tanks and the best filters for 5-gallon fish tanks. I’ve chosen 5 filters that I can recommend for nano aquariums that I will describe below in more detail.

Before I get to the filters in question, for those that aren’t familiar with these systems, let’s see the type of filters designed for use in small aquariums.

What Type of Filter to Choose for Small Aquarium?

When it comes to small aquariums, aquarists usually need to choose between two types of filters — power filters and sponge filters.

These two are the most commonly used and commonly available filter types available for small to medium aquariums.

Let’s see what the main characteristics of each:

1. Power Filters or Hang-on-Back Filters

As one of the most popular and widespread types of filters, hang-on-back filters are easy to install and offer multi-faceted filtration including mechanical, chemical and biological.

These filters are suitable for small to medium aquariums, they’re affordable and easy to operate. They’re fitted with a siphon tube and hang on the back of the aquarium.

If you’re raising fry, the inlet to the power filter can easily suck up the fry, so make sure to either buy a filter that’s also safe for fry or fry-proof the inlet yourself by placing something on it.

The cartridges in these filters can contain activated carbon or other filter medium, and they help with biological filtration by allowing beneficial bacteria to colonize the filter medium.

2. Sponge Filters

Sponge filters are more suitable for tanks with fry. These filters too, offer mechanical and biological filtration, although they can clog much easier if there’s too much debris in the tank.

Sponge filters are fitted onto the tubes of air pumps or power heads. They allow beneficial bacteria to develop and besides being used in tanks with fry, they’re also a great choice for hospital or isolation tanks.

They’re also easy to clean, but it’s important to use aquarium water when rinsing or cleaning it, otherwise the chlorine in tap water will destroy the colony of beneficial bacteria.

These two types of filters are the best when it comes to nano aquariums. Depending on their size, hang-on-back filters are suitable even for medium sized aquariums. Large filters will benefit from canister filters instead.

Best Filters for 5 Gallons Nano Aquariums

Preview Filter Name  
Tetra Whisper in-Tank Filter with BioScrubber for Aquariums 1. Tetra Whisper in-Tank Filter with BioScrubber
Aqua Clear - Fish Tank Filter 2. Aqua Clear – Fish Tank Filter
AZOO Aquarium Mignon Filter 3. AZOO Aquarium Mignon Filter
Aqueon Quietflow E Internal Power Filter 4. Aqueon Quietflow E Internal Power Filter
Aquapapa Corner Filter Air Driven Bio Sponge Ceramic 5. Aquapapa Corner Filter Air Driven Bio Sponge Ceramic


Since we’ve chosen 5 gallons as the typical size for nano aquariums, let’s see which filters are most suitable for these types of tanks:

1. Tetra Whisper in-Tank Filter with BioScrubber for Aquariums

Tetra Whisper in-Tank Filter with BioScrubber for Aquariums

This power filter uses small cartridges in a space-saving design to take up as little space as possible in your nano aquarium without compromising on the quality of the filtration.

The filter cartridges that are included in this in-tank filter use a two-step filtration process and are easy to replace when the time comes.

In the first stage of the filtration, the cartridge floss traps debris, fish waste and other particulate matter, while the second stage consists of an activated carbon filter medium that removes odors and traces of chemicals in your water.

The filter has a clip-on system to secure it on your aquarium and easily adjusts to low water levels and high water levels. You can easily hide the filter behind live plants, efficiently masking it if you want to delve into aquascaping.

The same filter is available for various tank sizes, so you can pick the filter that’s best suited for your tank size.


2. Aqua Clear – Fish Tank Filter

Aqua Clear - Fish Tank Filter

The Aqua Clear is a compact and complex power filter that filters water through a multi-stage process, creating a silent “waterfall”-effect.

It offers biological, mechanical and chemical filtration, and its patented Re-Filtration System allows you to adjust the flow rate when a gentler filtration is needed. When flow rate is reduced, up to 50% of the water receives multiple filtration.

As for the filter media contained by the cartridges in the Aqua Clear is layered as follows:

  • A foam insert that’s replaceable every two months and removes debris and suspended particles; its porous surface allows colonization by beneficial bacteria;
  • An activated carbon medium that adsorbs chemicals, VOCs, and traces of chemical disinfectants and odors; replaceable every month;
  • Ceramic rings that allow beneficial bacteria to thrive, replaceable every three months.

Simple to install and maintain, the Aqua Clear is a powerful, yet gentle filtration system that’s available for various tank sizes.


3. AZOO Aquarium Mignon Filter

AZOO Aquarium Mignon Filter

Suitable for nano aquariums, the Azoo Aquarium Mignon filter installs easily on the edge of your tank and has a quiet operation.

Although the filter is rated for 3-gallon tanks, it can easily handle 5 gallon aquariums as well, and according to its Amazon review it can even handle aquariums up to 10 gallon in size.

If you’re housing fry or small fish, I recommend using the prefilter included with this kit and set the suction/flow to low. You can adjust flow with the flow control knob on top of the unit.

Another plus of this affordable and compact power filter is that it doesn’t require external pump because it has one already attached to the unit.

The filter is shipped with two sponges, although you can use other sponges if you prefer. I recommend the smallest sized Biomax media and an Aqua-Clear sponge.


4. Aqueon Quietflow E Internal Power Filter

Aqueon Quietflow E Internal Power Filter

With easy set-up and amazing filtration, the Aqueon Quietflow is a great filter for nano tanks of 5 gallons and below.

The flow offered by the filter is perfect, there’s no other equipment needed to drive more oxygen into the water as the filter nicely breaks the surface tension with its flow from the top.

The filters are self-priming, and the filter kit includes the hanging clips and suction cups needed for installation. You can install it both on aquariums with and without frames.

The filter medium that’s included with the Aqueon is activated carbon, which does an excellent job at cleaning the aquarium of problematic ingredients. In case of power interruption, the auto-start pump restarts and resumes filtration.


5. Aquapapa Corner Filter Air Driven Bio Sponge Ceramic

Aquapapa Corner Filter Air Driven Bio Sponge Ceramic

This small corner filter offers mechanical and biochemical filtration thanks to its multilayered design that includes a top layer of white filter pad for mechanical filtration, a second layer of black bio-sponge for biochemical filtration followed by ceramic rings for the same.

The sponge filter requires an air pump and airline tubing, which are sold separately. As I mentioned, sponge filters are suitable for aquariums with small fry because they’re quiet and there’s no risk of fry getting stuck into the filter inlet.

The Aquapapa is easy to maintain, simply remove the sponge and give it a good rinse in aquarium water to get rid of trapped debris.

These were the aquarium filters most suited for nano tanks. I highly recommend getting a filter for your tank, because in small aquariums water parameters are notoriously difficult to keep stable.

Unless you’re a highly experienced aquarist, do not set up a small aquarium without a filter system, be it a power filter or a sponge filter with an air pump.


Sponge Filter & Air Pump

Although I’m a fan of power filters, I recognize that sponge filters are better when raising small fish or fry.

However, these filters aren’t of much use on their own, and you’ll need to use them with an air pump to achieve the mechanical filtration that will get rid of debris and other suspended solids from your water.

Therefore, if you choose a sponge filter, you will need an air pump too. The one I usually recommend is the Tetra Whisper, which is quiet thanks to the integrated sound-dampening chambers.

The air pump is available for different aquarium sizes, therefore, pick the size that’s suitable for your aquarium. The Tetra Whisper does not ship with airline tubing, but it’s available for purchase separately.


When setting up a nano aquarium, there are many factors to consider, especially that water volume is limited, and you need to maximize the available space.

However, skipping essential equipment like filters can prove to be a fatal mistake, especially if you don’t have any experience with tank maintenance and designing self-sustaining environments.

The filters for small aquariums that I discussed in this aquarium will prove to be an indispensable addition to your nano aquarium project and this will reflect in the health and well-being of your fish.

Whether you need a filter for a nursery tank, breeding tank or a hospital tank, these filters are suitable for all use cases and some of them can work efficiently even in larger tanks.

Updated: November 27, 2019
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