Do Betta Fish Need a Filter in Their Tank? (Must Read) is supported by our readers. When you buy through links on our site, we may earn a commission.

Outdoor situations are generally the only time a betta fish can live without a filter. This is because filtration is inherent in the habitat. But for people who believe bettas could live in a bowl or other small tank, you may be wondering “do betta fish need a filter?”

Keep reading to have all your questions answered!

Reasons You Need a Betta Fish Filter

A filter is necessary is to keep betta’s watery home clean and pure. If there isn’t one, the water becomes cloudy and bad bacteria replicates fast. This stresses out your pretty fish, weakening its immunity and increasing its vulnerability to illness.

Filters keep the tank free of debris, decay, old food, chemicals, bacteria and fecal matter. All this, if it remains too long in their environment, will cause bettas to get very sick.

Even with a filter, though, you still have to change out the water on a regular basis, but not as frequent as you would without one. Regular water changes replenish vital nutrients and minerals bettas need. Otherwise, they’ll suffer, get sick and likely die.

Protect Betta Immunity

Filters remove and dilute a build up nitrates, ammonia and nitrites. When water becomes too contaminated, the betta will become stressed, thereby weakening its immunity due to sustained ammonia poisoning. This can kill the fish if ammonia builds up.

Special sponges in the water filter help remove these harmful substances from the tank, maintaining a clean and safe habitat for your betta. Even though bacteria will still grow in your tank, a majority of it will reproduce in the filter.

Water Flow ; Oxygenation

Filters keep water flowing around in the tank. If water becomes stale and stagnant, it will absorb carbon dioxide from the air. This affects the pH balance of the tank and causes illness for the betta.

Filters oxygenate aquarium water. Although this is not as much of a problem for bettas, because they breathe from the water’s surface, other plants and fish sharing the same space with a betta will need it. Oxygenation prevents water from becoming stale and, thus, stops the betta fish from becoming very sick and creating a horrible odor in your home.

Can a Betta Fish Live Without a Filter?

If you don’t use a filter, bettas will survive but only with frequent water changes and additions, like air rocks. But even with the of best efforts, their life be far too short. Without a filter, chemicals and bacteria will fester inside the tank.

Also, the water will never be as clean as it should be and the number of required water changes will stress the betta. What’s more, it will create instability within the tank. Good bacteria must also have room to grow and constant water changing will inhibit that process.

Basic Types of Aquarium Filtration

There are three purification modes that keep the tank water safe and tidy for your beautiful betta. These can be separate mechanisms for the aquarium or there are some filters available that encompass all three:

  1. Chemical Filtration removes chemicals that shouldn’t be in the tank. Often, this cartridge comprises activated charcoal or carbon, designed to absorb the most amount of impurities possible. Most unknown and unpredictable chemicals come from tap water.
  2. Mechanical Filtration removes built up filth and makes it look clean. Replace these cartridges every other week or every month. The size of the filter and tank will determine how often it needs changing. Failure to change this will result in a marked difference in tank-water flow and movement. This is due to the fact that water can’t permeate a clogged cartridge.
  3. Biological Filtration removes harmful bacteria and is arguably the most important part of an aquarium filter. Bio sponges give good bacteria the impetus to exist in the tank, which is crucial in the nitrogen cycle. This helps breakdown decay so the water doesn’t become toxic to plants and fish.

What Is The Difference Between Ammonia, Nitrites ; Nitrates?

Understanding the nitrogen cycle of your betta’s tank allows you to comprehend what’s happening and why it’s important to have a filtration system.

Fungi and bacteria in the aquarium breaks waste down into ammonia. This includes rotting food, dead plants and organisms, fecal matter and any other biological or organic substances. This ammonia is detrimental to everything living in the tank.

Another bacteria, Nitrosomonas, breaks down ammonia produced from waste into nitrite. Nitrites, although not as deadly as ammonia, can still cause stress and disease issues for your betta fish.

Nitrobacter, yet another bacteria, then further breaks down nitrites into nitrates. Nitrates aren’t as toxic as ammonia or nitrites to betta fish, but water with heavy nitrates will cause algae blooms. This will present a danger to the fish.

The Importance of the Nitrogen Cycle

This cycle is important because it allows for good bacteria growth in the aquarium. The biological filtration system is what helps this process along. Keeping your ammonia and nitrite levels at zero parts per million (ppm) is an absolute must! To ensure algae blooms don’t develop in the tank, make sure nitrate levels stay at 20ppm or less.

Types Of Filters For Betta Fish

Filters are an important part of the aquarium’s ecosystem. There are many different types to choose from, with their own sets of benefits and pitfalls.

Power Filters

Hanging on the back of a small to medium-sized tank, Power Filters are the most popular and provide all three modes of filtration. They have a siphon to conduct good water flow in the tank. This mechanism also allows water to pump back into the aquarium once cleaned.

Filter clogging occurs if cartridges go unattended, creating a build up of toxins in the tank. Washing or changing the filter on a consistent basis is the only way to handle this. If the filter is a higher quality, the cleaning schedule will be less frequent.

Getting a biowheel for your Power Filter may be a good option to try too. Biowheels spin water passing through it. Because it sits a bit out of the water, each part comes in contact with air so good bacteria can grow in a large area.

Canister Filters

If you house many fish alongside a betta in an aquarium holding 30 gallons of water or more, a Canister Filter may be your best option. They are often installed under the tank and remove water through an external filter containing many tubes. A high-pressure pump pushes water through all three filters.

The maintenance and upkeep of these filters are more demanding than other kinds because of the various tubes. And, because the filter is on the outside of the tank, many parts and pieces will need cleaning once or twice a month. This will ensure everything operates right and extends the life of the filter.

Undergravel Filters

These filters are discrete and use many tubes pointed up toward the water’s surface. Placing a powerhead or an airstone on top of the tube will force water through the gravel. This operates as the mechanic and biological filtration in the filter. Debris from the tank gets trapped and the oxygenation from the airstone creates an ideal environment for good bacteria.

The major downfall of an undergravel filter is its inconsistency. Some spots in the water will have more debris than others because the water flows through varying areas at unpredictable rates. So, you have to use a gravel vacuum. If cleaning goes unattended, hydrogen sulfide pockets develop and these become poisonous to a betta. So, this type of filtration requires a little more dedication but the results are impeccable.

If you have plants growing in your aquarium, don’t use undergravel filters. The disturbances in the water from constant cleaning will upset them.

Internal Filters

Internal Filters sit inside the aquarium, either laid across the substrate on top of the tank or hung by a suction cup on a wall inside tank. These often need an airline outside the tank with a pump.

Air comes in through the bottom of the filter via the cartridge and then air bubbles of clean water generate from the top of the filter. There are two main kinds of internal filters:

  1. Sponge Filters – These provide only mechanic and biological filtration, so you’ll have to have an extra filter for chemicals. Sponge Filters also need an air pump for oxygenation. If you have a small tank for one betta, are using the tank as a hospital or creating a breeding tank, this may be a good option.
    1. To remove dirt and debris and keep the good bacteria, cleaning must be a weekly event.
  2. Corner Filters – These small, discrete devices sit at the bottom corner and come with an air pump for water. Corner Filters comprise all three modes of filtration. But, because oxygen levels tend to be low, the water pumped through isn’t as effective as other filters are if you have fish along with your betta.

A small tank with one betta is best for use with a Corner Filter.

What To Look For In A Filter For Your Betta?

As with anything requiring a certain investment of time and money, you want to make sure the filter reliable, high quality and solid. Cheap knockoffs and unknown manufacturers can put the health and life of your betta in danger. So, it will be worth it in the long run if you spend the extra cash on a filter that’s going to last.

First, decide how much work you are willing to commit to putting in the care and maintenance of your aquarium. Be honest with yourself and determine what kind of time and opportunity you’ll have to stay on top of consistent water changes and filter cleanings. A Canister Filter is going to be a lot more work than a Power Filter, for instance.

Regardless of your determination and dedication, make sure the filter is generally easy to clean. Parts, lids, tubes and other little pieces should be easy to dismantle and subsequently replace after cleaning them. The filter should be easy to remove and replace with little disturbance to the tank. This will, in turn, reduce stress to your betta fish.

Water Flow ; Modes of Filtration

Then, make sure the filter will produce a slow flow of water. If the pump creates too powerful a current, it will shove your betta around the tank against its will. This is going to stress out your fish. Bettas like a gentle flow of water in their environment, so get one that runs slow or one with a water-flow adjustment.

If the filter doesn’t have all three modes of filtration mentioned earlier, your betta will become stressed and sick. Biological and mechanical filtration systems are not optional, you must have them for your betta.

Even though a chemical filter isn’t an absolute necessity, you don’t know what kind of chemicals are lurking in tap water. So, it’s best to err on the side of caution and use a chemical filter.

About Biological Filters

A greater amount of surface area will hold more bacteria, fostered by the oxygen levels going through the filter. All bacteria produced through the nitrogen cycle depends on this high level of oxygen.

So, you want to make sure you have a large enough sponge exposed proportional to an equal amount of air. The goal is to get the most amount of oxygen into the sponge to cover the biggest area you can.

Do You Need a Filter for a Betta Fish?

If you want a your betta to live a long and healthy life, you have to use an aquarium filter. Filters remove dangerous substances via the three modes of filtration. Without one, the tank will become cloudy and filthy which is starting your betta on a path to destruction by poisoning.

If you don’t, you’ll decrease your betta’s lifespan and destroy their quality of life, however unintentional. Without a filter, many changes of water will have to occur and will stress your betta along with preventing good bacteria from growing.

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Michele Taylor
Michele Taylor

Hello, fellow aquarists! My name is Michele Taylor, and I am a homeschool mother of six children, which includes five boys and one girl. My kids range in age from five-years-old to eighteen-years-old.

Growing up, our family had a large aquarium with angelfish, goldfish, and lots of different varieties of neons. We also had a “suckerfish” that grew to be about six inches long.

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