Should You Let Water Sit Before Adding Your Betta?

The generally accepted and agreed-upon answer about how long water should sit before adding betta fish is approximately 24 hours.

That’s your short answer. The long answer is a bit more detailed. A great deal depends on whether you are using a new or established tank, what the chlorine and chloramines are like in your tap water, and whether you use a water conditioner.

A betta fish, otherwise known as a Siamese fighting fish, is a beautiful but delicate tropical fish, and it is not to be tossed into a bowl full of water and left to fend for itself. It makes an ideal pet, but buying a betta fish requires some forethought and planning, including water preparation.

Don’t be in a hurry. Instead, take the time to wait at least 24 hours before adding your betta fish to your tank. Some fish enthusiasts even recommend waiting up to two to three weeks before adding betta fish, allowing the tank to cycle fully.

The benefits of being patient are that the chlorine can evaporate fully, and the chloramine can dissipate. These can make your betta fish incredibly ill or even kill your newly purchased pet.

Waiting longer allows your tank to cycle through the filter and heat up from the heater you bought to keep the water at an optimal temperature for your fish. It also gives you a chance to check your tank for any leaks.

The longer you wait, the more beneficial bacteria will grow. If you are in a huge hurry, using a water conditioner can speed up the process.

How Long Should I Wait to Put My Betta Fish in New Water?

Introducing a fish to a new tank of water is a slow process. Once your tank water is prepared correctly, you can float your betta fish, gradually introducing it to its new environment and acclimatizing it to the difference in temperature between the water in the aquarium and the water in the bag or cup.

You will float your bag containing your betta fish in the aquarium water, making sure there is room for your betta fish to get air. They sip air from the surface of the water from time to time even though they breathe underwater.

After approximately 15 minutes, you can cut a small hole in the back and gradually introduce some tank water to the bag of water. Hold the plastic bag upright during this time.

After another 15-30 minutes, you can add another cup of water to the bag. This process allows your betta to get used to the pH and hardness of the water that will be its new home. After another 15 minutes, you can gently pour your fish into its new home. Don’t agitate the water too much. 

Should I Let Water Sit before Adding to Fish Tank?

Whether you should let your water sit before adding it to a fish tank is both a yes and a no. Allowing the water to sit depends wholly on whether it is 100% new water or only some water; no more than a third is being added to the tank to freshen the water.

In the former case, yes, you can let it sit, but it can be in the tank itself, allowing it to come up to temperature if no fish are involved. In the latter case, no. Replacing no more than 30% of the water allows the chlorine and minerals to be diluted to such an extent that it is not harmful to your aquarium pets. The temperature will not be affected too dramatically if you stick to the 30/70 rule. Lastly, if you are using chemically treated water, you do not need to let water sit before adding it to your fish tank.

How Long After Treating Water Can You Add Betta Fish?

Five to fifteen minutes is considered enough time. The conditioner must be added to the tank immediately before or after the water is added for maximum efficacy.

A water conditioner acts to remove impurities from the water like chlorine, chloramines, and heavy metals, all of which are unhealthy for your betta. If you purchase your betta fish from a pet shop, they may give you a bottle of water conditioner with your betta. If not, buy a bottle.

Can You Put Betta Fish in Water Right Away?

No, you can’t, not unless it’s a choice between life and death for your fish at that moment. Tap water contains chemicals and minerals which vary according to where you live, and not all of them are good for your betta fish. In particular, chlorine and chloramines need time to dissipate.

You can use a water conditioner to clean the water, but you are more likely to be successful if you gradually introduce your betta fish to their new watery home. Additionally, the water that your betta fish is in might not have the same pH or temperature as that of the water in your new home. Floating your betta gives your fish time to acclimate.

Ideal Tank Conditions for Your Betta Fish

You want your betta to be happy in their new home, so keep the following in mind. A betta’s natural habitat is murky, so bright lights and neon colors are not good. Instead, stick to neutral aquarium pebbles or gravel, and don’t put your betta near windows that will put your betta in full sun all day long.

As far as sizes go, don’t go smaller than a 5-gallon tank for your betta fish. A betta is tropical, and the water needs to be comfortable for them. Make sure to purchase a heater, especially if you live in a cold climate. 

When making a new home for your fish, you should know that it can take up to 24 hours for your water to reach the correct room temperature. As a shortcut, you can use near lukewarm water in your tank so that the heater doesn’t have to do all the hard work initially.


Ideally, you should wait approximately 24 hours before adding your betta fish to a new tank of prepared water. Established tanks may only require you to float your betta before gently introducing it to the water in the tank by gradually adding some to the bag or cup that your betta is in. This process takes approximately 45 to 60 minutes.

Don’t rush. Waiting 24 hours allows your water to sit and for the chlorine and chloramines to evaporate, your water to come up to room temperature, the growth of beneficial bacteria, and for everything in your tank to settle. After all, 24 hours is not that long to wait to provide your new pet with ideal tank conditions, and if you can, wait longer, giving your water more time to cycle fully through the filtration system.

You can read more on acclimating your betta fish here.

If you want to learn more about Betta’s behavior, advice, and tips, please visit our collection of Betta Tips Articles.

About the author

Hi, I am Alex.
My passion is aquariums. I am especially drawn to betta fish. I love experimenting, learning, researching, and writing about them.

You can find the articles I wrote here