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How Do You Keep a Quarantine Tank Cycled? (Answered)

If you’re wondering, how can you keep a quarantine tank cycled then you’re in the right place.

Here I’m going to answer the same question.

Normally, you don’t need to keep a quarantine tank cycled. However, you can keep your quarantine tank cycled by keeping hardy fish and a filter running in the quarantine tank.

How do you keep a quarantine tank cycled? (Answered) image

How to keep quarantine tank cycled?

Once your quarantine tank is cycled then you can easily keep the tank cycled by keeping a fish in the tank and a filter running and doing regular tank maintenance.

However, there are some unique things you’ll need to keep in mind while keeping a quarantine tank cycled.

1. Keep the setup simple

Your quarantine tank should contain only the necessary things.

It should only have a filter and a heater.

You should avoid keeping any substrate, decorations, and live aquarium plants in your quarantine tank.

Keeping your quarantine tank set up simple is important because the main purpose of your quarantine tank is to quarantine a new fish and treating a fish before adding it into your display tank.

And adding extra things like substrate and plants requires maintenance. And it can make things complicated while treating your fish.

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2. Add hardy fish in the quarantine tank

Once your quarantine tank is cycled then you will need to keep a hardy species of fish in the tank.

Some of my recommendations of hardy species you can keep in your quarantine tank are as follows:

  • Danio
  • Platy
  • Swordtail
  • Gopi
  • Molly
  • Play ko
  • Barbs

These fish will produce waste in the quarantine tank and the waste will produce ammonia.

This ammonia is food for the beneficial bacteria which is responsible for the nitrogen cycle.

So it will nourish the beneficial bacteria and keep them thriving in your quarantine tank.

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3. Set up and keep all the equipments running

You will need to keep all the equipment such as a filter, a heater running in your quarantine tank.

Ideally, you should try to maintain the same water parameters as your display in your quarantine tank.

It is very important to keep the filter running in a quarantine tank because the filter will not only keep the water clean but is also a very good place for beneficial bacteria to form their colonies.

Besides, when it comes to the filter for your quarantine tank, you should go for a filter in which you can easily remove chemical filtration like Carbon or Zeolite.

This is important because you can also use your quarantine tank as a hospital tank and treat the new fish. And in a hospital tank, you don’t want a chemical filtration because it can remove the medications from the tank.

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4. Keep up with the maintenance of your quarantine tank 

Though you have added a hardy fish in the quarantine tank, still, you will need to keep up with the maintenance of the quarantine tank to maintain a healthy environment for the fish.

The maintenance of a quarantine tank includes the following things:

  • On a daily basis, you should observe the behavior of your fish. Observing the behavior of your fish will tell you if it is doing fine or not. And you will be able to catch any symptoms of diseases at an early stage. Feeding time is a good time to observe your fish’s behavior.
  • After about 10 minutes of feeding your fish, you should remove any uneaten food from the tank.
  • On a weekly basis, you should clean the inside glass of your fish tank. And do a partial water change of about 30% of your aquarium water.
  • On a monthly basis, you should test all the water parameters of your fish tank (ph, ammonia, nitrite, nitrates) and make sure that everything is fine. I recommend API master test kit. It is pretty accurate and it comes with very helpful instructions to use it. You can check its reviews and latest price at Amazon here.
  • On a monthly basis, you can also check if any of the filters in your quarantine tank needs to be replaced.

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How to quarantine a new fish in an already cycled quarantine tank?

goldfish image with "QUARANTINING NEW FISH" text

So now you know how to keep your quarantine tank cycled. Let me tell you how to quarantine a new fish in the tank.

After getting a new fish, before adding the fish into the quarantine tank, you should first add the hardy fish which is already in your quarantine tank into your main display tank. And then add the new fish in the quarantine tank.

After that, you should keep and observe the new fish for about two to three weeks in the quarantine tank.

If everything looks fine i.e. if the fish doesn’t show any symptoms of any disease then you can put the fish into the main display aquarium. And then again put the hardy fish into the quarantine tank.

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Why you may not need or want to keep your quarantine tank cycled?

betta fish image with "NO NEED TO KEEP IT CYCLED!" text overlay

First of all, keeping a quarantine tank cycled is a hassle.

You will need to keep up with the maintenance of the quarantine tank if you want to keep it cycled.

Besides, after quarantining a new fish using the method I mentioned above, if you found the fish infected with a disease then obviously you will need to treat that fish in the quarantine tank before adding the fish into your main display aquarium.

But most importantly, after treating the fish you will need to clean your quarantine tank with dilute bleach solution.

Then you’ll need to cycle the quarantine tank again so you can put the hardy fish in it.

If you’re keeping your quarantine tank cycled because you’re concerned about cycling the quarantine tank when you’ll need it then the good news is there are a few ways to cycle your quarantine tank instantly.

You can instantly cycle your quarantine tank, add your new fish into the tank and medicate the fish if needed.

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How to instantly cycle a quarantine tank?

Adding a filter or filter media from an established aquarium i.e. the aquarium which is already cycled into your quarantine tank can instantly cycle your quarantine tank.

The thing is the filter or specifically, the filter media of an already cycled aquarium contains a lot of beneficial bacteria which is responsible for breaking down harmful ammonia produced by the fish into less harmful nitrite and nitrate which is basically cycling of a fish tank.

So when you add a filter or filter media from an established aquarium in your quarantine tank, you’re basically adding beneficial bacteria in your quarantine tank. And this will instantly cycle your quarantine tank.


You should always keep a sponge filter running in your established aquarium in case of an emergency like cycling a quarantine tank.

The extra filter will also work as a backup for your main tank in case your primary filter fails.

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How to store a quarantine tank when not in use?

After you are done with treating a fish in your quarantine tank then before storing it you will need to clean the tank and equipment.

You can clean your quarantine tank with a dilute bleach solution.

After cleaning the quarantine tank with bleach solution make sure to dry the tank thoroughly.

After that, you can store the quarantine tank or use it again.

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Related questions

What is a good size for a quarantine tank?

Usually, a 10-gallon tank is ideal for or a quarantine tank. Usually, the instructions about using the medication are according to a 10-gallon tank. So it becomes easier for you to use the medication if you have a 10-gallon tank.

However, if you keep small species of fish in your tank then you can also so have a 5-gallon quarantine tank.

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Can I quarantine fish in a bucket?

You can quarantine a fish in a bucket as long as you can provide a biological filtration in the bucket which you can easily do by adding a sponge filter into the bucket.

Though, the problem with quarantining a fish in a bucket is that you don’t get a good view of the fish in the bucket. This makes it hard to notice any symptoms of diseases on fish.

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Overall you can keep your quarantine tank cycled by keeping a hardy fish, keeping the equipment running, and keeping up with the maintenance of the tank.

Usually, aquarists don’t keep their quarantine tank cycled all the time. 

They set up the quarantine tank when they need it. And instantly cycle the quarantine tank with the methods I mentioned above and then add the new fish into the quarantine tank.

Photo of author
Prathmesh Gawai
He is the main author and editor at Aquagoodness.com. And he loves to share helpful information on aquarium and/or fishkeeping hobby. Prathmesh has over five years of aquarium and/or fishkeeping experience. Currently, he has a Betta fish tank. He has written hundreds of articles on various aquarium fish species and on fish tank maintenance over the last five years. Connect with him on YouTube here. Learn more about him here.

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