Do Betta Fish Need A Filter

Do Betta Fish Need A Filter?

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It was once accepted that betta fish could live happily in a tiny bowl or vase with no heater, filter, or -decorations. However, that myth has been dispelled, and for many years now, most responsible fishkeepers know bettas need to live in a proper aquarium setup with both a heater and a filter to thrive.

In short, in most cases, bettas need a filter and a heater.

In this guide, we discuss why this is the case, and we also take a look at what kinds of filters are available as well as what design is most suitable for bettas.

Quick Summary: Best Filter For Betta

Tetra Whisper Internal Filter 10 To 30 Gallons, For aquariums, In-Tank Filtration With Air PumpTetra Whisper Internal Filter
  • Convenient Design
  • Catches Debris
  • Universal Design
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Aqueon QuietFlow E Internal Power Filter Extra Small - 3 GallonAqueon Quietflow E Internal Power Filter
  • Efficiently Cleans And Filters Water
  • Removes Odors And Discoloration From Water
  • Carbon Cartridge Included For Chemical Filtration
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Lefunpets Sponge Filter Breeding Fry Betta Shrimp Nano Fish Tank for Aquarium Fish Tank 5 Gal-10 GalLefunpets Biochemical Sponge Filter
  • Soft Sponge Material
  • Easy To Operate
  • Perfect For Use
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Can betta fish live without a filter?

We just told you bettas need a filter, but to answer that question in detail, you need to understand more about the fish’s natural environment.

Bettas live in small bodies of still water, such as rice paddies, ditches, marshes, and ponds. Although the flow there is minimal, there’s enough water movement to disperse toxins like ammonia and nitrites, and any nitrates in the water are taken up by the dense aquatic vegetation and algae that grow there.

Natural events like rainfall also help to clean and replace the water. Wherever the betta lives in nature, the body of water will have a relatively large surface area, which helps to ensure good gaseous exchange. That means these bodies of water have plenty of oxygen for the betta to breathe.

In dry seasons, these tropical fish can end up living in small puddles where oxygen is less plentiful. That’s why the fish have evolved to develop the labyrinth organ, which enables them to breathe air.

So, in the wild environment, the betta’s habitat is filtered and oxygenated naturally.

A betta can survive for a short time in a bowl or small tank without a filter. That time can be extended if you carry out frequent water changes. However, your betta buddy’s life expectancy is going to be considerably shorter if you don’t have a filter in your tank.

Why is that? Well, for starters, a tank without a filter is never going to have perfectly clean water. Although you can carry out lots of water changes — probably every other day or so — that would most likely succeed only in stressing your betta.

Plus, the more water changes you make, the more unstable the tank’s water chemistry will be. That’s because you’ll be removing all the beneficial bacteria that will grow naturally within the tank.

Without a filter, the aquarium water won’t be circulated, so it will quickly become stagnant. Stagnant water is extremely unhealthy, and your fish won’t last long…and your home will smell as bad as the local duck pond!

All those harmful substances we mentioned earlier will accumulate in the water, albeit becoming more diluted with every water change. However, ammonia, nitrites, and nitrates will still be there, and that’s very dangerous for your betta.

Does a betta tank need a filter?

In comparison to your betta’s natural habitat, his tank is a closed environment that doesn’t benefit from water flow and rainwater that help keep the water clean. Also, if you keep your fish in a tiny bowl or vase, there’s little surface area for gaseous exchange, so the water will be low in dissolved oxygen for your betta to breathe.

In a tank without a filter, you’ll see the water becoming cloudy quickly as bacteria react to the presence of fish waste in the water. Your betta’s waste contains ammonia, and if there’s no filter in the aquarium, the ammonia builds up, quickly turning the environment toxic and potentially killing your fish.

What does a filter do?

A fish tank filter has several functions:

  • To prevent stagnation by circulating water around the tank
  • To remove solid waste particles from the water
  • To process ammonia and nitrate, rendering the water safe for your fish
  • To remove heavy metals and harmful chemicals from the water
  • To cause surface agitation, which improves oxygenation (Note that only some filters do this)

How does the filter work?

aquarium filter with fish

The filter works by pumping the water around the tank and drawing it through a series of different filter media and sponges. Colonies of nitrifying bacteria that live within the biological filter media process harmful ammonia and nitrites into less dangerous nitrates. Once the water has been through the filter, it’s clean and safe for your fish.

You’ll still need to carry out weekly water changes to remove excess nitrates from the water, and the filter media needs rinsing every month to prevent it from becoming clogged with sludge. However, the filtration system makes tank maintenance less time-consuming than it would be without a filter.

The Three Types of Filtration Methods

Most filter systems have three main elements: mechanical, biological, and chemical. These elements work together to keep the tank water clean and safe for your fish.

The whole system is powered by a pump. In some filtration systems, the pump is integral to the unit. It circulates water throughout the aquarium so all the water passes through the filter media. When choosing a filtration system, make sure the GPH (gallons per hour) rate is at least four times the total water volume of your fish tank.

Mechanical Filter

The mechanical filter is the first element of the system, which removes large particles of floating debris from the water. This keeps it clear and looking clean.

Chemical Filter

The chemical filter usually contains activated carbon, although there are other alternatives. The carbon removes any chemicals or heavy metals that are present in the water. Note that not all filter systems contain a chemical element.

Biological Filter

The biological filter is the most important element of the system when it comes to your betta’s health, as it provides a platform on which beneficial bacteria can grow. Those bacteria power the nitrogen cycle, which is crucial to the health of your betta’s tank.

The nitrogen cycle in brief

You can read about the nitrogen cycle in detail here. But here’s a quick explanation of how the cycle works and why it’s crucial to your betta’s health.

  1. All the organic waste products in your fish tank, including fish waste, uneaten food, and plant debris, are broken down into ammonia by various types of bacteria. Ammonia is highly toxic to anything living in your tank, and levels should be at zero parts per million (ppm).
  2. In the biological filter media, Nitrosomonas bacteria process ammonia into nitrites. Nitrites are still harmful to your betta, but they’re not quite as dangerous as ammonia. Again, nitrite levels in the water should be zero ppm.
  3. Finally, another type of bacteria called Nitrobacter processes nitrites into nitrates. Nitrates are not as harmful as ammonia and nitrites are, but levels in your tank should be 20 ppm or lower. Note that if nitrate levels are too high, algae blooms will occur.

The nitrogen cycle works provided there’s enough surface area for bacteria to colonize and grow. Suitable sites include the substrate, tank decorations, your viewing panes, and the biological filter media.

For the biological filter media to be effective, it must have plenty of surface area to hold the maximum number of bacteria. There must also be a good flow of oxygen through the media. Ideally, you need a large biological sponge that’s exposed to the air.

Types of filters

There are several different kinds of filters, all with pros and cons.

Hang-on-Back Filters

As their name suggests, hang-on-back (or HOB) filters are designed to hang on the backs of betta tanks, which saves space inside the aquarium.

HOB filters usually have three elements of filtration and have a kind of siphon that pulls air into the water to oxygenate it. Some HOB systems even have a BIO-wheel.

The BIO-wheel spins as the water passes over it so part of the wheel is in contact with the air. That clever design enables maximum bacterial growth over a huge surface area.

The main drawback of HOB filters in a betta tank is that the water return mechanism’s waterfall effect often creates a lot of surface agitation that can stress your betta and make it difficult for it to feed and breathe when it needs to.

Internal filters

Internal filters live inside the tank, fixed to the wall with suction cups. The main problem with using one of these powerful filters in a betta tank, however, is that the flow created by these filters is usually too strong for bettas.

Corner filters

Corner filters live inside the aquarium and are freestanding on the substrate in one of the tank’s back corners. The filter box contains filter media and is connected to a pump outside the tank by a piece of airline.

These filters are particularly powerful, and they don’t generate much oxygen, but if you’re using one of them in a small tank, it should be fine.

Sponge filters

Sponge filters are also placed inside the tank. They aren’t tremendously powerful, but they’ll work fine in a small betta tank. The filter uses an external air pump to draw water and air through the media. Sponge filters have just one kind of filter media — a sponge — which functions as both biological and mechanical filters.

One big advantage of sponge filters is that they’re extremely easy to maintain. All you need to do is rinse any sludge from the sponge every couple of weeks. And there’s a perk: there are no expensive cartridges to replace.

Undergravel filters

An undergravel filter is ideal if you want to run a system that requires virtually no weekly maintenance and can’t be seen in your tank.

The filter takes the form of a large plate with multiple slots in it. Two uplift tubes are fitted into the two back corners of the filter plate, extending to the water surface. An external pump draws water through the filter and circulates it around the tank.

The substrate acts as a biological and mechanical filter. Any debris in the tank is sucked into the substrate where it gets stuck. Thanks to the flow of oxygen through the filter plate and up through the substrate, the bacteria has everything it needs to grow.

The main problem with undergravel filters is that you can’t see how much muck is trapped underneath the filter plate. Each week, you need to vacuum the gravel thoroughly to remove excess waste.

If you neglect this task, pockets of hydrogen sulfide will form, and that can be deadly to your betta buddy. Once every year or so, take down the whole tank so you can remove the plate and clean underneath it.

Note that these filters don’t work so well in a planted tank, largely because of the disturbance cleaning the filter causes to real plants’ roots.

Canister Filters

Canister filters are placed outside the tank, usually out of sight in the aquarium cabinet. These are powerful filters that are ideal for large tanks that are over around 30 gallons.

Canister filters remove water from the tank into an external filter system. Once the water has been pushed through the filter media, it’s returned to the tank.

The main downside of this kind of filter system is that it tends to be maintenance-heavy. Plus, unless you have a large setup that contains not just your betta but lots of tank mates as well, you don’t really need a filter this powerful.



Will a filter hurt a betta fish?

Provided that all the moving parts of the filter (i.e., the impeller) are protected inside a box housing, your betta shouldn’t be injured by the filter.

Unlike fry, tiny fish species, and shrimp that are small enough to be sucked into the filter unit through the intake pipe, your betta’s too large for that to happen. If you’re still concerned that could happen, place a piece of mesh across the intake pipe.

Is the filter too strong for your betta?

The main issue between bettas and filters is that the water movement generated by the filter may be too strong for the betta to handle.

That’s the problem with having such a beautiful and flowing finnage: it makes it extremely difficult to swim in a strong current! If your fish is constantly struggling to get where it needs to go because of the water flow, it will become stressed.

How to tell if a filter is too strong for a betta

Watch your betta going about its daily business in the aquarium. Can it swim easily and without a struggle to get where it wants to? Does your pet rest calmly on leaves or the substrate or does it seem reluctant to do so? Does your betta seem unable to go to certain parts of the tank?

These could all be signs the filter is too strong for the typically active fish.

Can I turn my filter off at night?

No. For your filter to work efficiently, keep it turned on 24/7 except for cleaning and maintenance days.

Do I need an air pump too?

Most kinds of filters have a pump included in the design, so you don’t need to buy one separately unless you’re running an airstone as well as a filter. That’s not really necessary for bettas, since they don’t appreciate too much water surface movement, and a regular filter unit will provide sufficient oxygenation for the water in a small tank.

The exceptions are:

  • Undergravel filters
  • Corner filters
  • Sponge filters

All these designs of filters need a separate pump that lives outside the tank and is connected to the filter unit by means of a length of airline.

What’s the best filter for bettas?

What’s in the ideal betta filter, you ask?

  • Mechanical and biological filtration (Chemical filtration is nice to have, but it’s not essential)
  • Gentle or adjustable water flow so your betta can swim easily without becoming stressed
  • Easy maintenance and cleaning (Also note that filter cartridges can be expensive, so keep that in mind as you shop around)
  • Reliability is crucial. The last thing you want is for your filtration system to break down and put your betta’s health at risk, so be prepared to pay a little more for a reliable filter from a reputable brand.

Taking all those things into account, here are three of our favorite betta filters that are currently on the market.

Tetra Whisper Internal Filter

Thanks to its four different size offerings that range from up to 4-gallon to up to 40-gallon tanks, it won’t be difficult to find a Tetra Whisper Internal Power Filter that fits in your betta tank. We’re specifically highlighting the product meant for tanks that are 10-30 gallons.

Tetra Whisper Internal Filter 10 To 30 Gallons, For aquariums, In-Tank Filtration With Air Pump
  • UNIVERSAL DESIGN Tetra Whisper 20i Internal Filter is an all-in-one air pump and water filter system
  • INTERNAL FILTER Mounts on the inside of your aquarium with clip (included)
  • CATCHES DEBRIS Dense dual-sided mesh filters debris and fish waste

This tank clips to the inside of your aquarium, and the dual-sided mesh filters both debris and fish waste, guaranteeing your betta swims comfortably in a clean environment.

It’s designed to be air-driven and convenient, oxygenating water while filtering up to 125 GPH and using Bio-Bag cartridges that are easy to change.

Aqueon Quietflow E Internal Power Filter

Aqueon QuietFlow E Internal Power Filter Extra Small - 3 Gallon
  • Efficiently cleans and filters water
  • Easy to install using suction cups and/or hanging clips
  • Auto-start pump requires no priming, automatically restarts if power is interrupted and restored

The Aqueon Quietflow E Internal Power Filter comes in four sizes suitable for 3, 10, 20, or 40-gallon fish tanks. With this variety, you’re bound to find one that suits your betta tank.

This power filter is designed to hang vertically inside the tank on the back wall. The filter contains mechanical, chemical, and biological media and is powered by an auto-start pump that needs no priming. In the event of a power outage, the pump restarts automatically.

The filtered water is returned to the tank via a gentle waterfall system that doesn’t cause much surface movement, so your betta will be able to swim, feed, and breathe at the surface without difficulty.

Bonus: for your peace of mind, these power filters come with a limited lifetime warranty.

Lefunpets Biochemical Sponge Filter

Lefunpets Biochemical Sponge Filter comes in several sizes, including this one that’s ideal for a 5-10 gallon tank.

This sponge filter is super safe for your betta fish and does a good job of picking up floating debris from the water. The unit is also very easy to set up and clean; all you need to do is squeeze the sponges in some tank water once a week as part of your partial water change routine.

Though this filter is very reasonably priced, note that you’ll need to buy a separate pump to power it.

Final Thoughts

So, do betta fish need a filter? Now you know the answer to that question is yes! Betta fish do need a filter in their tanks to keep the water clean and free of harmful substances so they can stay healthy.

A good filter for bettas contain mechanical, chemical, and biological filter media. You also want a product that doesn’t generate too much flow through the aquarium, which would make it difficult for your betta to swim, so keep that in mind as you shop for an aquarium filter for your fishy friend.

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