Do Betta Fish Need a Filter?

Betta fish are better off in tanks with filters. This is not only to help keep the water looking clean but to make the water healthy enough for fish and live plants to comfortably live in a glass box. This is because of something called the nitrogen cycle.

betta fish swimming

The Nitrogen Cycle

Your betta will be stuck swimming in the same place where he or she will poop. This poop, and any uneaten food rotting in the tank, create chemicals dangerous for your fish like ammonia.

Beneficial bacteria are needed to convert ammonia to less harmful nitrate. The whole nitrogen cycle is more complicated than that, but that is the general gist. Beneficial bacteria do not live in the water but on surfaces. Your filter provides a lot of surfaces for the beneficial bacteria to live and thrive.

Filters do more than that, but helping the bacteria is a good reason to get a filter for your tank.

Sponge Filters

One of the most commonly seen filters in fish stores is the sponge filter. This is because if you have a lot of tanks, the sponge filters are the most economical to use. When bits of stuff start floating around your tank water, you know it’s time to clean the sponge. Clean it in old aquarium water to keep the beneficial bacteria happy. You also need to add an air pump or a water pump to create the necessary flow. An air pump will also help to oxygenate the water

The good things about sponge filters include:

  • They work. As long as you clean them when they get too dirty, they are very good at keeping the water clear.
  • The sponge provides ample space for beneficial bacteria to live.
  • They are easy to maintain. 

Problems with sponge filters include:

  • They only do mechanical filtration and biological filtration once the beneficial bacteria colonize the filter. The sponge filter does not provide for chemical filtration.
  • They need to stay inside the tank, so they take up room that could be used for decorations or plants.
  • You cannot hide them with plants or decorations because that will block the waterflow and stop the filters from working.
  • You need to change your water and the entire filter more often.

Power Filters

Also called Hang On the Back Filters. 
Full disclosure – these are my favorite types of filters. They provide excellent mechanical, biological and chemical filtration.

My reasons why:

  • They’re easier to maintain than sponge filters. Just change the disposable cartridge when the water becomes cloudy.
  • They need not be completely submerged in the tank water to work.
  • They do not take up room inside the tanks.
  • Everything you need is included. 

Problems with hang on the back filters include:

  • Including the cartridges, they’re more expensive than sponge filters.
  • They can be loud. 
  • The motor inside can short out after the power goes out. 

Corner Filters:

A cheap filter often seen in pet stores is the old-school box filter, also called a corner filter, which is a clear plastic box you fill up with your choice of filter media like bits of charcoal and filter floss. They are cheap and provide a low current that bettas tolerate. You also need to add an airline hose and an air pump to create the necessary bubble flow.

This filter is placed at the back of the tank, facing forward to fit in a corner. This type of filter does its job by doing what water changes should otherwise be doing – but much more often. This type of filter was more popular in the past.

Canister Filters:

These are big filters for aquariums of 40 gallons and more. These are the more expensive and sophisticated filters.

This filter is placed outside the tank with a tube that brings water from inside the tank to the filter, where it drains back down into the tank after filtration. They provide excellent mechanical, biological and chemical filtration and occupy minimum space inside the tank.

Under Gravel Filter or UGF

Another type of filter that I personally do not recommend is the under gravel filter. As its name implies, it can only work if your substrate is gravel, since anything finer than gravel will clog it completely. I find these difficult to maintain and easy to clog. You also cannot use live plants with them.

What Happens if the Power Goes Out?

All of these filters need electricity in order to run them. Bettas are hardy enough to usually survive a few days of a cold snap. However, ammonia and other bad chemicals may soon build up in your tank water.

If the power is out for a day or two, your betta should be all right. If the power is out longer than that, you need to do partial water changes every day until the power comes back on and the filter starts working again. 

If your pipes have frozen, then you need to use bottled water to do the partial water changes. Remember not to change all of the water at one time, because this could shock your betta.

What About All Those Bettas Living in Bowls without a filter?

You’ve seen the rows of bettas living in tiny little bowls in the pet store. The employees there may even say that bettas prefer being in small bowls because being in a larger tank will shock them.

This is untrue. Bettas in the wild live in territories of about 20 gallons. Your betta will be much happier and healthier in a larger tank than in a little bowl, or even a one-gallon aquarium.

There may be times when you have to place your betta in a small home without a filter. This should only be a temporary solution. If your betta is in such a small home, the water needs partial change almost every day.

If I Get a Filter, Will I Still Need to Do Water Changes?

You still need to do partial water changes of 10 to 25%. In general, the smaller the tank, the more often you need to do partial water changes.

The reason goes back to the nitrogen cycle. Although the beneficial bacteria turn ammonia into nitrate, too much nitrate will kill your betta just like too much ammonia will. Performing regular water changes helps keep nitrate down to levels that will not bother your fish.

Water changes help for other reasons. If you’ve scraped a thick layer of algae off of your aquarium walls, chunks of it are now floating around your tank water. Doing a partial water change helps remove some of the excess algae. Your filter will help with this, too.

It’s best to wash any of your algae-covered decorations or artificial plants in old aquarium water that you can get with a water change, rather than rinsing the objects with fresh water from the tap. Your tap water may have chlorine, heavy metals, and other nasty chemicals that could harm your fish and beneficial bacteria when you place the decoration back in your tank.

So, Do Betta Fish Need a Filter?

Yes, your betta needs a filter. This helps not only keep the water clear by trapping any debris but helps provide a home for beneficial bacteria to grow. The bacteria help to keep the water healthy enough for your betta or live plants or any other fish in the aquarium. Although you have a filter, you still need to do regular partial water changes.

If you want more tips and guides on aquarium filters, please visit our collection of articles here.

About the author

Hi, I am Rena.
I grew up in a house surrounded by fish tanks.
I have spent my life caring for and writing about fish.
I have studied journalism and worked for online and print magazines.

You can find the articles I wrote here