How Long Does it Take to Acclimate Fish to an Aquarium?

Buying fish for your aquarium is always exciting but many complain that their fish die soon after they introduce them to their aquarium.

You cannot just dump a new fish into your aquarium and expect it to thrive.

To ensure that your new fish survives in its new environment, you must first learn how to acclimate a fish to the aquarium.

A smooth transition is the ultimate way to acclimate the fish to its new home.

Most people will tell you that it takes about 15 minutes for fish to acclimate to an aquarium. While this is partially true, it takes at least an hour for a new fish to adjust entirely to a new environment.

Float the bag in the aquarium until the water reaches the same temperature as that in the aquarium.

Give the fish enough time to adjust by adding a little of aquarium water to the bag every 5 minutes.

It can take even longer for bigger fish.

Acclimating Your Fish

There are a few vital steps that you need to follow to ensure that your fish acclimates to your aquarium without any problems.

The whole process requires patience and keen care on your part.

Rushing through the process can cause shock and stress to your new fish.

Dumping the fish with the pet store water directly into the aquarium is not a good idea. It can contain diseases and parasites that you don’t want to transfer to your aquarium.

By following these simple steps, you can successfully acclimatize your new fish to your aquarium:

Preparation before Introducing the Fish to the Aquarium

When you first buy new fish from the pet store, you should bring it home immediately without delay.

This is because the water in the plastic bag neither has sufficient oxygen nor do fish like to be in plastic bags.

After bringing it home, dim the lights in the room and turn off the aquarium lights.

This is to prevent any shock or trauma to the fish due to the sudden change in lighting.

Once your fish adjusts to the new environment, you can be less careful about lighting. But it is best to introduce your fish to a dim environment initially.

Next, rinse off the exterior of the plastic bag that contains your fish. This is to prevent any contamination of aquarium water when you put the bag inside.

Pour out excess water from the bag but leave enough that it covers the dorsal fin of the fish.

Float the Bag in the Aquarium

The next step is to open the bag and roll the top down four or five times so that it floats in the aquarium without sinking.

Now place the bag into the aquarium and let it float for 15 minutes.

If you feel that the bag is still unstable in the aquarium, a few more rolls might make it float on the top of the water.

Letting the bag float in the aquarium water will gradually make the water in the bag become the same temperature as the water in the aquarium.

The open-top will allow the oxygen to get to your fish.

Add Aquarium Water to the Bag

After letting the bag float in the aquarium for 15 minutes, you have to add half a measuring cup of the aquarium water to the bag.

Wait for 5-10 minutes and do it again.

This slow process will allow your new fish to gradually acclimatize to the change in temperature and water composition, etc.

Taking it as slow and steady as needed will increase its chances of survival.

It will grow accustomed to its new setting without any stress or shock. Keep adding aquarium water to the bag every 5-10 minutes until the bag is full.

Now, take out the bag and pour half of its water into the sink and float it back again in the aquarium. Keep adding a half cup of aquarium water in the bag every 5-10 minutes.

Repeat it until you are sure that the water in the bag is of the same temperature as the water in the aquarium.

Your fish is now all set to go into its new home.

Release the Fish into the Aquarium

For releasing the fish into the aquarium, you will need a small net.

Dip the net into the bag, gently lift the fish out of the bag and place it into your aquarium. You should use a slow swooping method to lift the fish gently.

Make sure that the fish does not get tangled in the net.

Although you should be gentle, remember to be quick as well when you transfer the fish into the aquarium.

You cannot hold your fish out of the water for long. You can hold the bag just over the water surface in the aquarium and quickly transfer the fish from the bag to the aquarium with the help of the net.

Why Do You Need to Acclimatize Your Fish to Your Aquarium?

It is not just the temperature of the aquarium water that your new fish needs to adjust to.

More things make acclimatizing your fish fundamentally crucial for their survival in a new home.

Here are some other factors that make this process necessary:

Aquarium Water Composition

All species of fish need set water parameters to survive in an aquarium.

Before introducing new fish to your aquarium, you have to make sure that the water conditions are perfect for the fish.

More fish die due to pH shock than any other reason when people first introduce them to an aquarium.

Gradually adding water to the bag not only regulates the temperature but also makes the fish grow accustomed to the water’s pH value, hardness, and the presence of other compounds.

It is best to test the water before adding a new fish to the aquarium.

This will help you ensure that the water conditions and composition are appropriate for the type of fish you are going to introduce to the aquarium.

Pre-Existing Community in the Aquarium

Another reason why acclimatization is necessary is that you want to make sure that it gets along with the pre-existing community of your aquarium.

Fish are not always peaceful and friendly towards other fish.

If you already have fish in your aquarium, they might not be happy about the addition of a new fish to the aquarium. They might view your new fish as an intruder.

Putting a bag containing the new fish in the aquarium will give them a chance to get along and become familiar with each other.

If the pre-existing community does not accept a new addition, at least there will be a barrier between them and the new fish.

New Sounds

Like lights, fish are also sensitive to sounds.

The sound of the filters and waterfalls can be a little disturbing to your new fish as it is new to this environment.

The plastic bag will muffle these new sounds to a great extent, making the fish familiarize themselves with the new sounds gradually.

This will prevent any shock or stress to the fish.


As important as it is to acclimatize new fish to the aquarium, it is equally necessary to carry out this process meticulously.

Never just dump the fish directly into the aquarium.

This can cause stress and shock to your new fish. Even worse, you can end up killing your fish if you do not acclimatize them appropriately to their new environment.

Patience, care, and following all the steps are the key to making your fish comfortable in a new setting.

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