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How Often To Change Betta Fish Water? (Guide + How To Change It)

Renee Whitmore
Last Updated on
by Renee Whitmore

A betta fish in a fish tankBetta fish are great fish that can live for a long time if properly cared for. Changing their water safely minimizes their stress is a small part of the care that will keep your Betta around for years to come.

Here are some quick facts about changing betta fish water:

  • Bettas have a labyrinth organ that allows them to breathe oxygen from the air rather than filter water through their gills. At the same time, however, regular water changes are necessary to keep bettas healthy and happy.
  • Betta tanks should be no smaller than 2.5 gallons, though 5 gallons or more are better.
  • A filtration system is necessary for all but the most experienced of fish keepers.

How Often To Change Betta Water?

Generally speaking, you’ll want to change your Betta’s water about once a week. Although betta fish can tolerate lower oxygen in water than other fish, there are other reasons to change the water.

In terms of pH, betta fish prefer a 7.0 “neutral” pH. Although they can handle alkaline or slightly acidic water, it’s best to maintain a neutral pH. As they live in unchanged water, however, the water becomes increasingly more acidic. This is because of the waste produced by the Betta after eating and drinking.

In addition to detoxifying the water, doing frequent water changes is a good way to keep the tank clean for your fish.

How often you change your water will also depend on whether or not you have a filter.

Do Betta Fish Need a Filter?

Although betta fish can survive in low oxygen level environments, it’s typically best (especially for inexperienced pet owners) to have a filter. Why?

Betta fish, in fact, can live without a filter. Their hardiness and ability to breathe air from the water’s surface allow them to survive in conditions that other fish wouldn’t. That said, however, having a tank without a filter is a lot more maintenance.

The good thing about a filter is that it not only aerates your Betta’s water while helping to break down some of the harmful chemicals that can kill a fish.

That the filter reduces the toxicity of water means that you won’t have to change out the water as often as you would if you didn’t have a filter. However, one thing to keep in mind is that not all filters are created equal when it comes to betta fish.

Probably the highest recommended filtration system for betta fish is a sponge filter. A sponge filter is perfect for Betta because they’re weak enough that Betta can still swim around freely in their tanks.

If the water stream produced by a filter is too powerful, Betta can have trouble swimming.

Related Article: Do betta fish need bubbler?

Betta Water Change: What Else to Know

If you decide not to use a filtration system, you should be aware that caring for your fish will be much higher maintenance. Keeping a single betta fish in the minimum size of a 2.5-gallon tank without a filter, you’ll want to change the water in small increments (20-30%) every day.

Changing out the water for a betta often can be stressful for the fish and is extremely labor-intensive. Therefore, we highly recommend all betta fish owners put their fish in larger tanks with filtration systems.

How Big Should My Betta Fish Tank Be?

Betta can survive in 2.5-gallon tanks. At the same time, however, 2.5 gallons is the bare minimum. Preferable would be at least a five-gallon tank with plenty of coves and enrichment activities to keep your fish mentally healthy.

How to Change Betta Fish Water


Ready to start changing your betta fish water? Once you’ve decided how often change betta water (based on the size of your tank and whether or not you have a filtration system), here are the steps:

  1. Remove your Betta. Take a small cup and fill it with water from the betta’s tank. Take the Betta out of the tank with a net and put it in the cup. Keeping your Betta out of the tank while you change the water will be much less stressful for it.
  2. Clean the walls of the tank. When you change the water, you should also wipe down the walls of the tank. This will get rid of the algae, which in large quantities can be toxic for the fish, by severely reducing the available oxygen in the tank.
  3. After you’ve cleaned the walls, let the debris settle on the floor of the tank. Then, using a siphon pump, take water directly from the bottom of the tank. In this way, you’ll be changing out the water and removing the debris that has built up through your Betta’s living.
  4. Replace the water. Try to keep the water at the same temperature as the tank water (slightly warm), and if you’re using tap water, be sure to condition it.
  5. Place your Betta back in its tank.
Betta Fish
About Renee Whitmore
Renee Whitmore
Renee Whitmore is an American college professor and freelance writer from North Carolina. She holds a Bachelor’s Degree in English and a Master’s Degree in English Education. When she is not driving her teenage son to wrestling practice or learning the ins and outs of Fortnite from her younger son, she is working on her first book to be published soon.
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