Do betta fish need a filter?

by | Blog, Breeding and Care, Freshwater Fish

1. Introduction

A well-kept fish tank is the foundation of your fish’s health. In a clean, well-maintained tank that is sized appropriately, your fish will thrive. Betta fish are no different. Filters help keep an aquarium clean, but still, many novices wonder: Do betta fish need a filter? Yes, they do. Bettas have been one of the most ill-treated fish in the aquarium hobby, unfortunately – In part because there are many misconceptions about what they need.

I’ll discuss why betta fish need a filter, and what some of the exceptions and misconceptions are.

PS- Many people also think that bettas can be kept in a small bowl or a 1 or 3 gallon tank, but this isn’t true, either. They should have a minimum of a 5 gallon tank – 10 is preferred.

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2. Purpose of a Filter in an Aquarium


Keeping a filter in fish tanks is required in order to create a safe environment for fish. A filter helps clean the aquarium water by removing toxic gases and impurities. Uneaten fish food, fish waste, dead fish, decomposed plants and decayed algae are all things that give rise to ammonia levels in fish tanks. Without a filter, your fish are defenseless against them, and can die. Filters also help oxygenation, allowing your fish to breathe easily in clean water.

Biological filtration is also a good option for fish tanks because it’s inexpensive and powerful.

One way to look at it is that a fish tank filter is responsible for the removal of dead things before they turn into poison.

3. Do Betta Fish Need Filters?


Drumroll: Yes! Betta fish need a filter. One of the reasons this has gotten confusing for beginner aquarists is that bettas have a special organ called a labyrinth, which actually allows them to breathe oxygenation from the air. Cool, right?! This is also why you might hear them referred to as labyrinth fish (the type of fish that have this organ).

If you think that a filter is just for oxygenating the water, and you hear that betta fish can breathe from the air, you might think that you don’t need a filter because after all, betta fishie can just swim up to the surface and breathe, right?

Nope. That’s only part of the story. There’s more to filters than only oxygenating the fish tanks. Though betta fish can breathe air and are hardy tropical fish, they also need a clean tank free of ammonia in order to survive.

Like all other fish, betta fish also produce waste, leave uneaten food, and pollute the betta tank. All these things require a filter for removal so that they don’t turn into toxic ammonia. Ammonia will kill your fish as fast as you can blink. And even if the fish doesn’t die right away, trace amounts of ammonia and/or a dirty tank environment makes it impossible for the fish’s immune system to fight off disease, and causes them to have a shortened lifespan.

A filter provides a poison-free environment.

You may also have heard that you can just not add a filter, and instead keep changing the water in the betta tank very often. But here’s the thing: Water change depends on the size of the tank, and what’s inside it. A tiny tank should have a water change somewhere in between every 3-4 days, and once a week. A large tank may be closer to every week or every 10-14 days. Water changes should also be adjusted if there’s more waste production or uneaten food left in the fish tank (in other words, frequency is determined by water quality and parameters).



Betta fish picture



Bettas are frequently found in small tanks (5-10 gallons) that already need more frequent changes as compared to medium and large tanks. Do you really want to be doing water changes every other day?

Maybe more to the point: This super frequent changing of water is also not a good thing. When you change the water, you remove impurities, but you also remove good bacteria that keep nitrites and nitrates (and therefore ammonia) in check, and the betta tank balanced and healthy. When you remove this beneficial bacteria, it can cause an ammonia spike and kill your fish.

Keeping a filter in your betta tank prevents this from happening.

Also, let’s be real: Even though betta fish can breathe from the air, they’re still fish that also breathe from the water, and oxygenating the water is a good thing that helps them have a healthy, quality life.

In short, betta fish produce waste just like any other fish, which is dangerous as it converts to ammonia if left unchecked. More frequent water changes can help, but they also pose their own risks, and it’s safer and easier to just use a filter.

The caveat that I will add here is that there are experienced and advanced aquarists who have created planted tanks that are so perfectly engineered, they are able to keep impurities in check primarily by replicating a natural biotope. However, this is considered an advanced technique. A large portion of betta fish are kept in small tanks by novice aquarists who don’t have these skills.

4. Betta Fish Habitat with Filtered Tanks


To create a betta fish habitat with filtered tanks, filters like sponge filters, hang-on-back (HOB) filters, and canister filters can be used. Betta fish have long, delicate fins, and they also evolved in environments that have still or slow-flowing water. Moderate and high water flow stresses them out, and they don’t do well in high-pressure filters. This is why sponge filters are best for bettas.

Too much water flow can cause stress and illness for a betta fish, and sometimes even injury.

5. Benefits of Betta Tanks with Filters


I recommend betta tanks with filters because it’s not only more convenient than trying to manage deteriorating water quality with lots of water changes (and the accompanying risk with removing beneficial bacteria) but it’s ultimately better for the fish: They’re able to have a healthier, safer environment, and are also able to breathe from the water.

Healthy fish means not only reduced risk of illness, longer lifespan, and humane fish keeping, but also better coloration and activity in the tank.

With a filter, you don’t have do a partial water change every 24-48h, or constantly worry that ammonia and nitrate levels are building up. Chemical and biological filtration help remove these life-threatening chemicals.

Finally, filters are a place where beneficial bacteria grows. These are the good bacteria that “eats” up nitrates and prevents them from becoming ammonia. You want them on your team!

6. Betta Fish Habitats Without Filters


I mentioned earlier that many people think that betta fish can live in filter-free/unfiltered tanks, due to their ability to breathe from the air at the surface. But as you can see, there’s way more to it than that, from cleanliness, stress, and ammonia to humane fishkeeping and convenience.

It’s also worth asking how you’d feel if you had to live in a tiny, dirty, space that required you to go to one corner to breathe.

The only reasonably humane habitats I’ve seen set up without a filter are those developed by highly advanced aquarists with a deep understanding of aquarium biology that allows them to create large “biotope tanks” that are exactingly engineered to essentially produce their own oxygen by copying a real habitat found in nature. In other words, this is a small percentage of people, not your average novice or intermediate aquarist.

Betta fish breathe air, but they still need a filter.

7. What Happens If You Don’t Use a Filter in Your Aquarium?



Siphoning gravel in dirty tank



If you don’t keep a filter in your aquarium, the fish may live for a little while, but they’ll eventually die – If not right away, their health will deteriorate and/or their lifespan will be shortened.

Aquariums without filters build up nitrates and the water quality deteriorates quickly since toxins aren’t being removed, making it difficult for fish to survive or to have a healthy immune system.

Frequent water changes can help, but large, super frequent water changes removes beneficial bacteria that keeps the tank’s ecosystem balanced, which can cause an ammonia spike (the frequent culprit of waking up in the morning to dead fish).

Dirty water and the buildup of toxins in the tank ultimately mean that the fish is unable to fight off their equivalent of a common cold; It shortens their lifespan and can quickly lead to death.

Don’t overshoot it when it comes to changing your filter, either, or it’ll look like this (eg, bad for your fish):



Dirty aquarium filter


I wouldn’t want to breathe that, and neither should your betta.

8. Do I Need to Cycle a Betta Fish Tank?


Yes, a betta fish tank needs to be cycled. All tanks need to be cycled. When a tank is cycled, it has good bacteria that helps to remove ammonia and other toxins that kill fish. In fact, not cycling a tank is a common culprit for the death of beginners’ fish.

9. Types of Filtration Methods

9.1 Mechanical Filtration


In mechanical filtration, mechanical filters catch the large particles (the ones that may float on the water’s surface, for example). These particles could be fish waste, uneaten food, or dead plants. The filter media will capture the particles and then transfer the clean water back to the fish tank.

If the holes in the filter media are too large, it won’t be able to capture as many waste particles as it could; Filter media with small holes can easily trap more waste. How often you change the filter media depends on the tank (how stocked it is, bioload, size, etc) but it can be anywhere from every 2 weeks to every month. If you don’t change it on time, it’ll begin to lose efficiency.

9.2 Chemical Filtration


Chemical filtration is the process that focuses on removing harmful chemicals from aquarium water by using activated carbon or activated charcoal filtration. These filter media will basically suck in the harmful chemicals of aquarium water, leaving your fish with a cleaner, chemical-free environment. These systems usually need changing every 3 months or so.

9.3 Biological Filtration (Beneficial Bacteria)


One of the most effective, efficient filtration methods is biological filtration. Biological filtration helps remove unwanted toxins from the fish tank with the help of living organisms that grow as a result of the nitrogen cycle.

As we know, ammonia is the biggest enemy of fish. A small amount of ammonia in the fish tank results in damaging the gills, organs and outer body of the fish, so it’s absolutely necessary to instantly remove ammonia from the tank.

Beneficial bacteria play an important role in this; They convert ammonia to nitrite and then to nitrate; These good bacteria (primarily nitrobacter and nitrosomonas) perform the task of cycling the fish tank. In a healthy, established tank, you’ll find beneficial bacteria growing on the filter pad, gravel/substrate, and surface of the fish tank. There’s even bottled beneficial bacteria that you can buy,

10.  Types of Filters

Betta fish

10.1 Hang-On-Back Filters /Power Filters


Power filters are also called hang-on-back (HOB) filters, and this one’s self-explanatory: They usually hang on the back of the tank. They’re one of the best filters you can put in an aquarium, due to their efficiency, and easy placement and maintenance.

Power filters/HOB filters are well known in the aquarium world, and highly recommended because they have the capacity to use all three filtration methods: Chemical filtration, mechanical filtration, and biological filtration.

HOB/power filters use mechanical filtration by passing the aquarium water through filter media using a water pump. There, all the waste and particles are captured by the filter media, and then the clean water is transferred back into the tank.

They use chemical filtration to remove harmful chemicals from aquarium water with the help of fixed activated carbon inside. After removing the chemicals, the water is sent back to the fish tank.

Power filters use the beneficial bacteria that are grow on the cartridge for biological filtration.

These filters are excellent because they don’t take up much space in the tank, and their cartridge is easy to change or clean if it gets blocked. Lots of different brands and companies offer these, and the filter will come matched to specific tank sizes.

10.2 Sponge Filters

Freshwater sponge filter

If you’re looking for a filter for a small betta aquarium, a sponge filter is a good choice. Sponge filters don’t work as efficiently as power filters do, but they’re still good at trapping waste particles and transferring clean water back to the tank. They’re a good aquarium filter for fish that need low flow.

Sponge filters do need an air pump, as they use this to draw in water and oxygen and to help good bacteria to grow.

That said, they’re not efficient for removing chemicals. The upside to this is that they can be used in breeding tanks and hospital tanks in particular, as they don’t remove the medication in their filtration process.

10.3 Canister Filters


For a large fish tank, canister filters are an excellent option. Aquariums of 30 gallons or more typically require a canister filter. These filters are fixed outside the tank (rather than inside), although sometimes you’ll find them fixed to the bottom of the tank, or beside it.

Canister filters are effective at handling all three filtration methods (mechanical, chemical, biological), but they do have several tubes that require cleaning and maintenance.

10.4 Under Gravel Filters


This one is self-explanatory: Under gravel filtered are literally placed under the substrate of large tanks (usually 40 gallons or more), although they’re sometimes fixed above the fish tank.

The filter consists of a broad and spacious plate that’s placed under the gravel at the bottom of the tank. It works with the help of an air pump and external uplift tubes. Water in the aquarium moves from the gravel into the filter and then back into the tank after getting cleaned.

These filters use mechanical and biological filtration; They suck in waste particles and yield cleaner water, and can also grow beneficial bacteria as well.

10.5 Corner Filters


Corner filters are great for small tanks since they don’t take up much room. As the name implies, these filters are made to be placed in the corner of the tank. Corner filters use filter media and air pumps to work.

You can usually adjust the flow of water in the tank with these filters. Though they’re good at cleaning the tank by taking in the waste particles and chemicals, they’re not efficient at oxygenation.

11.  FAQs

Betta fish

11.1 Do Betta Fish Need a Filter?


Yes, betta fish do need a filter. They’re hardy, but they still need clean water to survive, just like any other fish. Without clean water, they’ll eventually get sick and die. Just because bettas are able to breathe supplementarily from the air doesn’t mean that they don’t benefit from being able to breathe from the water like other fish. Plus, filters keep the water clean, which keeps your betta fish alive and healthy.

11.2 What’s the Best Filter For Bettas?


Both sponge filters and hang-on-back (HOB) filters are good for betta fish tanks as they remove toxins/unwanted particles from the tank. With HOB filters in particular, be sure to adjust the water flow as betta fish require very slow-moving water that mimics their natural habitat.

11.3 What’s the Best Filter Strength for Bettas?


The flow of aquarium water should be according to the size of your tank and the fish you have in it; Bettas don’t require a very strong filter, and the best strength for your betta tank is around four times the total space of the tank. For example, a 30-gallon tank’s strength should be around 120 gph.

11.4 What Happens to an Unfiltered Tank?


Unfiltered tanks are the source of ammonia, the biggest killer of fish. If you don’t filter your tank, it’ll get stinky and dirty which will build up stress in your fish. Unfiltered tanks also cause suffocation for the fish which will cause them to become ill, and even die. This is a result of a lack of proper nitrogen cycle in the tank.

11.5 Can Betta Fish Live Without Filter?


Betta fish, or any fish for that matter, may be able to live without a filter for some period of time, but they will most likely get sick and die because it’s very difficult to maintain good water quality in a small tank without a filter. Most betta fish are kept in small tanks (5, 10, 15 gallons). While they’re hardy and can breathe from the surface, the other important functions of a filter remain undone, such as teh removal of uneaten food, fish waste and dead plants. Some advanced aquarists may be able to do this with a perfectly engineered biotope tank, but that is totally different and out of reach for novice and even intermediate aquarists.

11.6 Can Betta Live without an Air Pump and Filter?


Betta fish can live without a filter temporarily, but they will likely eventually get sick and die (see answer above). Yes, you do need a filter in a betta tank.

However, they don’t necessarily need an air pump as they are able to breathe through their labyrinth organ.

11.7 How Do You Set Up a Betta Fish Tank Without a Filter?


This is an advanced strategy and I don’t recommend it for beginner or novice aquarists at all. It’s hard to do properly. Here’s how it works: Live plants work as natural filters which help remove toxins from the tank. Advanced aquarists can carefully engineer a tank to replicate a natural biotope and its water conditions, balancing the tank without a filter. I am hesitant to give this information here because I don’t want everyone running out to try this; This is for an aquarist who really knows what they’re doing. These tanks to require frequent monitoring and water changes as well.

11.8 Do Betta Fish Need a Heater?


As bettas are tropical fish, they like to live in warm water. The required temperature for them is 75-80°F, so yes, they do need a heater. The only exception is if you’re living in a very warm, tropical climate.

11.9 What Do Aquarium Filters Do?


Aquarium filters help remove fish waste, uneaten food and other poisonous chemicals to provide fish with a healthy and comfortable environment.

12. Final Thoughts


Betta fish do need a filter, especially since they usually live in small tanks, where the water quality can and will deteriorate rapidly. Any fish might be able to survive for a time in an unfiltered environment, but eventually nitrates will build up and they will probably die from ammonia poisoning. This happens unfortunately frequently.

There are some advanced aquarist techniques out there regarding relying on biological filtration, but this is definitely not something that you should be trying if you’re a novice or even intermediate aquarist.

Filters like a sponge, hang on back (HOB), corner, and canister filters help perform chemical, biological and mechanical filtration for a healthy tank. Filters for betta fish tanks should be carefully adjusted to ensure the flow is slow enough for the betta.





Additional Sources/Resources/Reading



To say that I’m obsessed with all things saltwater is a bit of an understatement. Aquarium Passion has served freshwater and saltwater aquarium hobbyists for over 10 years, and I'm committed to keeping the information accurate and free. My post-bac certification in Sustainability informs my writing about aquarium conservation efforts. When I'm not writing at AP, I'm out in the ocean or researching weird fish.


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