Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

How to Change Betta Fish Water (5 Step Guide)

Sarah Psaradelis

By Sarah Psaradelis

red betta in aquarium

If you are a beginner and new to the aquarium hobby, you may be confused about how to go about changing your betta’s tank water. This is a process that is widely discussed, yet you may be confused why you even must change the water in the first place. You may also have many questions, such as if you should do a water change even if you have a filter or how to conduct a water change while a tank is cycling.

While all of this can be a daunting task, this article is going to dive deep into how you can conduct a proper water change with as little effort as possible while providing you with tips on how you can ensure that the water is kept as clean as possible. Which will minimize the number of water changes you have to do.

aquarium plant divider

Why Should You Change Your Bettas Water?

betta fish in aquarium
Image Credit: Kosit Pajuthai, Shutterstock

Essentially, a small body of water can quickly foul up due to your bettas waste and rotting food. In the wild, there are enough environmental aspects to naturally control the waste present in the water. There are plenty of large plants and organisms that can naturally break down the waste. However, in a tank, there is nowhere for the waste to go once it has been converted through the nitrogen cycle. This makes it important to remove a percentage of the old water and replenish the tank with fresh, dechlorinated water. Thus, lowering the amount of waste and toxins that have built up in the tank over time.

How Much Water Should You Change?

The amount of water that should be changed depends on two factors, the amount of stocking in the tank and the size of the tank. Both play a role in the overall water quality. If you have a lot of tank mates with your betta fish, the toxins will accumulate rapidly, and you will therefore need to do water changes more frequently. Whereas in a small tank, the water to toxins ratio can quickly become dangerous than if it was a large tank with an appropriately sized body of water.

Let us have a quick look at water changing checklist according to the size of the tank:

5 gallons 40% water change weekly
10 gallons 30% water change weekly
15 gallons 20% water change weekly
20 gallons 10% water change weekly

If you have tank mates with your betta fish besides snails or shrimp, the tank size should be increased, and the water changes should be done twice a week instead.

Tips to Keep the Water Clean

woman feeding betta fish in aquarium
Image Credit: Alexander Geiger, Shutterstock
  • Run a sponge filter in your betta’s tank alongside a cartridge filter. We highly recommended running activated carbon and ammonia chips in the cartridge filter due to its excellent cleansing abilities.
  • Do not overfeed your betta fish because the food will start to rot in the water if it has not been eaten in a few minutes.
  • Avoid placing dirty hands inside of the tank and rather use a net to move things around.
  • Ensure that the tank has been fully cycled before adding in the betta fish. The nitrogen cycle is the accumulation of nitrifying bacteria that turns ammonia into nitrate which is a less toxic version of ammonia. The cycle can take up to 8 weeks, and you may have to conduct small water changes every week so that the tank’s water does not foul up.

Tank or Bowl?

Many people believe that they can get away with keeping their betta fish in a bowl by doing 100% water changes weekly. This is simply not true, and it is best to avoid housing your betta fish in an appropriate aquarium. A standard rectangular tank is a way to go. Bowls, bioorbs, and vases are way too small to comfortably house a betta and the water can become extremely toxic in less than 24 hours.

betta fish inside aquarium
Image Credit: Yan Cabrera, Pixabay

The Role of a Filter in a Betta Tank

Filters are there to suck up debris and water and filter it through the inside of the system, to then release clean and nitrified water back into the tank. Having a filter in the tank does not mean you do not have to do water changes; it just helps keep the number of water changes significantly less which means less work for you.

How to Change Your Bettas Water in 5 Simple Steps

1. Gather a large bucket and a siphon.

Turn off the filter and heater before you proceed with the water change. If you run a heater and filter when they are not fully submerged will cause them to break and burn out.


2. Place the siphon in the tank and place the smaller tube in the bucket.

man changing water in aquarium
Image Credit: hedgehog94, Shutterstock

3. Pump

Pump or suck at the end of the siphon until the water is pouring into the bucket.


4. Stop

Stop once the recommended volume of water is removed according to the necessary percentage of water you are changing.


5. Replace the water

Replace the water with fresh water in the bucket that has been dechlorinated to remove chlorine. Pour it into the tank and immediately turn on all the equipment.

Benefits of Gravel Vacuuming

aquarium gravel cleaning
Image Credit: Andrey_Nikitin, Shutterstock

Sometimes changing the water is not enough to keep the toxins down. You may need to use a gravel vacuum to suck up waste and leftover food between the substrates. Food left to rot in the substrate can cause major problems with water quality. It may also be necessary to lift rocks or driftwood to suck up any trapped debris. Gravel vacuums are generally inexpensive and easy to find in local pet stores.

aquarium plant divider

Wrapping It Up

Changing your betta’s water does not have to be a difficult task, and it can be made easy by following the proper procedures. Ensuring the water quality is kept clean using a filter and nitrifying bacteria is just as important. Your betta will be much healthier and happier if they are kept in clean water conditions. This will reduce the risk of ammonia burns, popeye, and fin rot. All of which are common problems if your betta is kept in dirty water. This will help your betta to live a full long life and increase their lifespan.


Featured Image Credit: MANU PARADY, Shutterstock

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database