Choosing a filter for a small 3/4/5 gallon fish tank which stocks Betta fish or other small tropical fish requires careful consideration. The best small fish tank filter is one that not only keeps the aquarium clean and clear but also doesn’t stir up the water too much to stress the fish. In this article, I will provide you some of the best aquarium filters from various types including internal, power, canister, corner and sponge filters that you can choose for your small fish tank.

Tetra Whisper 10i in-tank filter for 3-5 gallon tanks

Tetra Whisper 10i in-tank filter4.5 star rating (4.5/5 by editor)Check on
  • Type: internal filter
  • Flow rate: 80 GPH
  • Ideal for: 3-5 gallon fish tanks
  • Media: medium Whisper Bio-Bag cartridge, Bio-scrubber pad

If you love to use traditional in-tank filter (internal filter), the Tetra Whisper 10i in-tank filter is a great choice. It is rated for up to 10 gallon fish tanks and certainly works well for 3-5 gallon aquariums. The filter uses a medium Whisper Bio-Bag cartridge and a patented Bio-scrubber pad to keep the aquarium clean and clear.

Bio-scrubber padBio-scrubber pad

The Whisper bio-bag cartridge is a floss pad filled with activated carbon that removes odors and discoloration, and keeps the water clear (mechanical and chemical filtration). The cartridge is very cheap, easy to assemble, easy to replace and only needs to be changed once a month. The Bio-scrubber pad provides the house for helpful bacteria that processes nitrogenous toxins from fish waste and uneaten food (biological filtration).

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AZOO Mignon Filter 60 for nano aquariums up to 3.5 gallons

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You may keep small fish like Neon Tetras, Guppies, Bettas or shrimps in your small tank and having a too strong filter will suck the fish into its chamber. Besides, too strong water output produced by the filter also causes very fast water movement that can stress the fish by forcing it to keep in constant movement with no rest. Don’t worry! This nano fish tank filter with its adjustable flow rate will protect your fish from being sucked up.

Water intake with pre-filter spongeWater intake with pre-filter sponge

The AZOO Mignon Filter 60 is loved by its powerful features such as small compact design, very quiet performance, easy maintenance. It is designed to be safely used for Betta and small tropical fish. Its adjustable flow rate and the pre-filter sponge in the water intake will prevent small fish from being sucked into the filter chamber. The large filter chamber of filter make it a good filtration system. With its design, you can buy and use your own filter media as you think best for your fish.

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Deep Blue Professional nano filter for up to 4 gallon tanks

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  • Type: external power filter (HOB)
  • Ideal for: Betta fish tanks, nano aquariums up to 4 gallons
  • Filtration types: mechanical and biological.

Deep Blue Professional ADB88700 Biomaxx Nano Filter can do well for small Betta fish tanks or aquariums up to 4 gallons. Moreover, the filter come with an adjustable flow control knob make it perfect for Betta fish as well as other small fish which love to live in a silent and clean water environment.

Deep Blue Professional ADB88700 Biomaxx Nano FilterDeep Blue Professional ADB88700 Biomaxx Nano Filter

The inside of this filter is an abundant place to contain various types of filter materials, ensuring your aquarium water is properly purified and ideal for stocking fish. You can use the filter cartridge coming with the product or buy your own filter media to set up the filter as you want. You can buy some ceramic rings or Bio-sponges to add to the filter to perform the most effective biological filtration for keeping your fish healthy.

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Zoo Med Nano 10 external canister filter for 5 gallon aquarium

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  • Type: canister filter
  • Flow rate (gallons per hour):  80 GPH
  • Ideal for: 5 gallon aquariums
  • Filtration types: mechanical, biological, chemical
  • Used for: freshwater or saltwater aquariums
  • Includes: sponge, bio ceramic, carbon media, spray bar system.

A power filter is just strong enough to keep your small aquarium clean; however, if you want to use a canister filter for the tank though it is more expensive than other filters, the Zoo Med Nano 10 external canister filter will make you pleased. It comes with most thing you need for the setup including various types of filter media and a spray bar.

This canister filter can perform all 3 types of filtration (mechanical, biological, chemical filtration) that keep your small tank clean and clear. The large capacity of the filter chamber is able to accommodate more filter media for the best filtration. You can choose your own filter media to put into the filter and don’t need to use ones included in the package.

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Sponge filter for 3 – 5 gallon breeding or fry tank

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  • Type: sponge filter
  • Used for: 3-5 gallon tanks, can use more than one sponge filter for larger size tank for efficiency
  • Filtration types: mechanical and biological
  • Filter sizes (D*H): 2. 2″ x 2. 8″ (5. 5 x 7 cm).

A good fish tank filter to use in small fish tanks is the sponge filter. This filter is powered by an aquarium air pumps (buy separately) to make a suction force that traps waste matters in water. Because the suction force is distributed throughout the sponge, it will not suck up even a new-born fish that makes the sponge filter ideal for breeding or fry tank. Besides, the sponge filter will provide sufficient mechanical and biological filtration to keep your fish tank clean and clear.

The sponge filter is very easy to set up and maintain. To clean it, just remove the sponge and give it a couple of squeezes in a bucket filled with the aquarium water (NOT tap water) to remove the debris on its surface. Remember not to use tap water because chlorine compounds from tap water can kill the helpful bacteria in the sponge, affecting its efficiency of biological filtration.

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Read more about sponge filters:

Tips for keeping your fish healthy in a small aquarium


Honestly, if you’re just starting off fish keeping, having a small fish tank is really not a good idea. A small aquarium contains a small volume of water (obviously) which tends to shift conditions a little too rapidly to be easily controlled. Temperatures change very fast, pH levels fluctuate rapidly and waste build up is frequent, making it require a little more maintenance than a larger fish tank. As you know, a 20 gallon aquarium is recommended for a beginner because it is easy to maintain this size tank than smaller ones.

Small fish tanks are often sold as a complete setup like the Marina LED aquarium kits which you can get online or any pet store. These kits usually comes with a hood, lighting and a small filter for small aquarium. However, if you don’t like to buy a kit or you are finding a new supply to replace the old one damaged, you must choose the right type fit for your small tank in order not to disturb the peaceful life of fish.


You will need to perform your weekly a quarter water change for your small fish tank to ensure that the environment you create is ideal to maintain the aquatic life you are keeping. A good filter may reduce the frequency of water change, however, it’s a must to ensure the health of your fish.

The last point to keep in mind is the number of aquatic life you plan to have in there. Don’t immediately dump in a bunch of fish into the water from Day 1. Firstly, a small fish tank will not support too many fish so keep it to a minimum. If you do plan to have a few more fish in there, take it in stages. Putting too many fish in at one time will raise the nutrient level in the tank, causing a bacterial bloom which will cause cloudy water harmful to the aquarium lives.

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