betta in a tank with filter
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Do Betta Fish Need a Filter in Their Tank?

While it’s possible to keep a betta without using a filter, it’s safer for the fish and more efficient to use one. This is because manually cleaning a betta tank is not only strenuous, but also time consuming. Although bettas are a resilient breed of fish, every species has a limit and it’s best to protect your betta as well as you can from stress and sickness, so they can live to the fullest.

When keeping a betta fish, try as much as possible to imitate its natural environment. This means the water that the fish calls home must undergo adequate testing and maintenance.

This maintenance could be done manually or by using filters. We recommend using a filter as it’s a more efficient and consistent method of maintaining the betta fish’s environment.

Shop our recommended filters below and read on to learn more about choosing the right filter for your betta’s tank.

05/24/2024 07:20 pm GMT

What Are The Different Types of Filters?


It wouldn’t be entirely inaccurate to say the betta fish breathes air. This is because bettas have an evolutionary trait that allows them to gulp air from the surface of the water when they find themselves in shallow waters with low oxygen levels. This ability comes from their labyrinth organ, classifying them as Anabantoidei or labyrinth fish.

Like most living organisms, bettas depend on oxygen to survive, which they either get from the surface of the water or the conventional way, which is when oxygen is diffused into the water through oxygenation and taken into the fish through its gills. 

In the case of tanks or bowls without filters, the water becomes stale and no longer oxygenated. This situation reduces the fish’s lifespan while simultaneously creating a foul odor in your house. 

Filters bacteria and harmful substances

Besides suffocating the betta and creating a foul odor, the lack of filtration means harmful bacteria can harm the betta. This, coupled with the stress and weakened immune system due to living in dirty and contaminated water, can hamper the betta’s and shorten its life.

This dirty water results from the accumulation of debris from various sources like decaying matter, harmful bacteria, rotten food, chemicals, and feces, which are detrimental to the fish’s health. 

The accumulated debris also causes a build-up of nitrate, nitrites, and ammonia, which in concentrated amounts can stress your fish out, weakening its immune system and making it more vulnerable to diseases such as fin and tail rot, which is the most common ailments in small unfiltered tanks. 

A filter eliminates these harmful substances by sucking the water and passing it through a rigorous filtration process. After this process, the tank water becomes safe and clean for your betta.

It’s important to note that the smaller the volume of your tank, the faster the water quality will decline and the more difficult it will be to maintain. So without filters, a regular change of water is mandatory; however, changing the water, again and again can stress out your betta as well, and inhibit the growth of good bacteria in the tank. This is why a filter is the best option as opposed to a tank with no filter, or worse, a bowl. 

A fish tank filter does just what it sounds like. It filters and removes harmful substances, waste, and chemicals from the fish tank. It also ensures proper water oxygenation to extend the fish’s life span.

There are three types of filters based on their mode of operation: 


As the name suggests, these filters are living organisms that actively process and convert the fish’s waste into less dangerous or toxic substances. They’re considered the most important type of filtration in an aquarium.

Ammonia, commonly found in aquariums, is a very toxic and dangerous chemical to bettas. Even small amounts can cause significant problems for the fish, such as damaged fins, inflamed gills, swollen eyes, appetite loss, lethargy, algae blooms, and eventually death. 

Biological filters (mainly bacteria and microorganisms) can perform tasks such as converting the harmful ammonia into less harmful nitrates and further into even less toxic nitrites. The bacteria species primarily responsible for this type of filtration are the Nitrosomonas and Nitrobacter species, both of which are critical parts of the nitrogen cycle. 

These bacteria and microorganisms hence live in a symbiotic relationship with the fish. 

The biological filtration kicks in once a fish tank has successfully been cycled. An aquarium or tank is said to be cycled when it has been allowed to sit and cultivate a population of living nitrifying bacteria, such as the Nitrosomonas species and Nitrobacter species. This usually takes 2-4 weeks to happen. 

The bacteria find the physical spaces within the tank to be an excellent place to settle and colonize. As such, some aquarists would add “filter media” inside the tank to encourage bacterial growth. More on this below.


Mechanical filters function by pushing the water from the tank into a “filter media,” which essentially sieves out large, free-floating particles. These solid particles include uneaten food, fish waste, and decaying plant material. After the particles are trapped, the filtered water continues through the process and goes back into the tank. 

A mechanical pump’s efficacy is heavily dependent on the filter media’s density and size. This is because filter media with larger pores are likely to catch far fewer particles than filters with smaller pores. 

Depending on filter brand and type, mechanical filter media can include filter cartridges, fibrous filter pads, sponge filters, foam filters, filter floss, or micro-fiber water polishing filter cloth. 

Be sure to occasionally clear out the filter media to avoid clogging. If this occurs, the particles will no longer be filtered from the water and will float around or dissolve, contaminating the water more. In addition to clearing the filter media out, it should also be changed periodically. 

Mechanical filtration, most times, is coupled with biological filtration to get a much more effective filtration system. 


This type of filtration focuses on removing specific chemicals from the tank by passing the water through a medium, such as activated carbon, zeolite, or other chemical resins. 

The filtration works by extracting the dissolved waste products from the water itself. For example, activated carbon removes chlorine and chloramine, dissolved proteins, tannins from bogwood, and foul odor from water, while zeolite effectively removes ammonia from the water.

Although effective, this filtration can not replace biological filtration as it doesn’t remove ammonia from the water nor break it down. 

Chemical filtration requires consistent maintenance as the chemicals can grow ineffective over some time. For example, activated carbon becomes saturated in about 60 days (3 months), so it must be changed periodically to remain effective. Zeolite, too, loses its effectiveness around that time. If your fish is sick,refrain from using chemical filtration when there’s medicine in the water, as it will filter the medicine and lose its effectiveness. 

Among all the filtration, chemical filtration is the least recommended method, as some plants can already perform the task effectively; however, it’s useful when there’s an outrageous amount of chemicals within the water. 

Regarding bettas, we recommend a mixture of biological and mechanical filtration. This is to ensure the fish are kept in an optimum environment where they can grow and live. If you wish, you may also throw in a chemical filter for extra maintenance; however, it isn’t necessary. 

What is the Right Filter Strength for My Betta?

To know if your filter is too strong for your betta, you must study your pet. If the filter is too strong for the betta, the fish will find it hard to move freely across the aquarium or tank. This is because the filter would create strong currents that stress the betta. 

If your betta is struggling to get to the surface for air, hiding and scared, and frantically swimming in the current, your filter is probably too strong. 

An overly strong filter can severely stress your betta fish and lead to complications such as fin damage, injuries, and even death. On the flip side, after becoming physically exhausted, they can also be tossed around the tank or even sucked up by the filter‘s intake tube. 

To rectify this, first check the water level of your tank, as tanks with a low water level will create strong currents. If this isn’t the case, consider reducing the filter‘s output or swapping it out for a more suitable filter

Sponge Filters

For small tanks and aquariums, we recommend using a sponge filter. This filter is most suitable for small tanks and is exceptionally compatible with bettas and shrimps. The sponge filter is essentially an air pump filter that uses bubbles of air from an air pump to draw water through a sponge. This sponge then proceeds to filter the water of debris and impurities that it may have contained. 

This filter is a perfect choice for bettas as it allows biological and mechanical filtration and also has an added bonus of oxygenation (obtained from the air bubbles). 

They support biological filtration by acting as a large surface area called air stones, for bacteria and microorganisms can colonize in order to make the tank cycled. 

This filter runs almost no risk of creating strong currents that can stress the betta and are affordable and easy to install and maintain. For maintenance, gently squeeze and rinse the sponge in old tank water. The sponge should be replaced as needed.

Hang-on-back Filter

Another perfect filter option for bettas is the power filter option, also known as the hang-on-back. They are primarily used for medium-sized tanks and aquariums.

They work by drawing in water from the tank into a filter chamber, where the water is filtered through a filter cartridge before being sent back to the tank. 

This filter is perfect for bettas as its filter power can be adjusted. Most filter cartridges have a pouch that allows you to insert material for chemical filtration, such as activated carbon. This will enable you to remove toxic impurities and odors from the water.

The water also goes through mild oxygenation during the move into the filter chamber, allowing bacteria to grow on it and hence supporting biological filtration. 

Power filters are not only easy to install, but they are easy to maintain. When the filter becomes clogged, rinse it out or have it replaced. 

Best Filters For Betta Fish

The best betta filter is one that does not toss your betta around the tank like a balloon, while performing its maintenance duties. 

Here are some of the best betta filters you can find on the market:

Aqueon QuietFlow LED PRO Aquarium Power Filters: this power filter guarantees the cleanest, clearest, healthiest water for your fish. The filter provides mechanical, chemical, and even biological filtration, all in its straightforward and efficient design. It also has an internal pump design that ensures silent operations and continuous flow rates with less chance of leaking as well as auto-start, self- calibrating features, and a lifetime warranty. 

Penguin Power Filters: A bio-wheel power filter that offers biological, chemical, and mechanical filtration. It has an adjustable mid-level intake tube, which can be attached to improve the water circulation within the tank. It also has a two-piece vented cover for convenient filter cartridge access and quiet operation. It filters in 3 stages:

  • Mechanical filtration through the use of its Penguin Rite-Size Filter Cartridge that essentially sweeps away all the debris 
  • Chemical filtration: through the use of its Black Diamond Premium Activated Carbon, which removes not only chemicals by also foul odors from the water 
  • Biological filtration: through its state-of-the-art bio-wheel that is guaranteed to increase the growth rate of beneficial bacteria. The BIO-Wheel now features 50% more surface area.

The Tetra Whisper IQ Power Filter with Stay Clean technology: is a silent power filter that guarantees that your water will be clean and healthy. The filter contains bio-scrubbers that help cultivate bacteria and encourage biological filtration, as well as a smartpath spillway system that ensures the water’s oxygenation. It also includes a sound shield for quiet filtration of less than 40 dB self-calibrating, and a capacity of 30 gallons of water. 

05/24/2024 02:46 pm GMT

AQQA Aquarium Internal Filter, Submersible Power Filter: This power filter has an adjustable flow as well as an ultra silent biochemical sponge for the quiet filtration of water. 

It comes with cartridges to ensure the water is well and a 3-in-1 multi-function aquarium filter. This filter comes with two kinds of water outlets and an air tube; you can switch to increase oxygen and filtration. Thefilter also creates a wave that makes the pump function faster.

The Breakdown

Bettas are a resilient and elegant species of fish. Their tenacity and adaptability allow them to survive in harsh environments and, as such, can live in a tank without a filter. Having said this, as responsible pet owners, we must take care of and protect our pets by any means necessary. 

Our goal should not just be to let them live but to allow them to thrive in our homes. This means, adding an appropriate filter for your betta fish tank, to keep its home clean and liveable.

Are you new to betta fish keeping? If so, check out the only betta fish care guide you’ll ever need.

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