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How To Easily Setup a Freshwater Aquarium Quarantine Tank

It’s great that you are taking the initiative to find out about and set up a quarantine tank. Fish are living creatures that deserve to be taken care of in the best way possible to ensure they have a healthy and long life.

A quarantine tank is probably easier to set up than you expected which is another great reason why every fish owner should have one. Let’s get right to it.

What Do You Need in a Quarantine Tank

 A quarantine should consist of a few things and that is all. These might be obvious to most people but still need to be mentioned to make sure you get your tank set up correctly the first time you do this.

An Aquarium Filter;

  • A filter will be needed to filter the water as you would require in a tank that has inhabitants full time. More on this below but your quarantine tank needs to cycle and have beneficial bacteria.

An Aquarium Heater;

  • A heater is required to make sure the temperature replicates the temp of the main tank and is set to the proper temperature range that the types of fish you own require the water to be.

Aquarium Lighting;

  • Lighting is required for a quarantine tank just like it is required for any other tank. Try to have the same type of bulbs running on both of your aquariums. Of course when you don’t have fish in the quarantine tank you do not need to turn them on.

Hiding Places;

  • Some sort of structure the fish can hide in so it feels safe and doesn’t get stressed out.
  • If you don’t have some type of hiding place or places for your new or sick fish they could become stressed and you might end up with Ich because of that.
  • If you place a couple of aquarium safe pots laying on their side or a couple of fish houses that should be good enough. Even fake plants will work if the fish you purchase are quite small.

A Word of Caution;

  • A quarantine tank should not have any type of substrate. You do not want anything to hide out in the gravel and infect the next fish that is placed in the aquarium. A glass or acrylic bottom is fine.

Does a Quarantine Tank Need to be Cycled?

 The quick answer is yes. Your quarantine aquarium must be cycled just like your main aquarium. You also must keep the aquarium running 24/7 so when needed you can use it immediately.

If you don’t know what cycling a tank means I have a very good article on the subject. You can find it here at “How to Cycle an Aquarium”.

Are Quarantine Aquarium Tank Water Changes Necessary?

Yes water changes are necessary for quarantine tanks. Not only are water changes necessary, keeping the beneficial bacteria in the tank living and thriving is required.

Small water changes should be performed every couple of weeks. Because you don’t have much of a bio load on the filtration of the tank you don’t need to do weekly water changes. If you performed about 10% to 20% water change that would be sufficient.

To make sure you keep living beneficial bacteria in the tank I would recommend you take the sponge from the quarantine tank and place it in the main tanks filter for 4 hours every two or three weeks then put it back in the Q tank.

You can also put a small amount of flake food in the Q tank once a week so it breaks down letting the water run through the process of keeping beneficial bacteria alive. Again make sure to read my article about the Nitrogen cycle.

large aquarium

What is the Best Size for a Quarantine Fish Tank?


Some people might think the smaller the tank the better and go with a 2 or 5 gallon aquarium. That might be fine if you know you will always only have one fish at a time in the tank. Let me ask you this.

What if you purchase 5 or 6 fish at the same time? Do you think they would do very well in a 2 gallon aquarium for a couple weeks?

Maybe, maybe not. They might start picking at each other biting each-others fins. Eventually killing one another.

A 10 gallon aquarium obviously gives you more room and the tank is still small enough that you can keep it somewhere out of the way without ever really noticing it.

Some people might question, why not have a 29 gallon aquarium or so on. I think that would be excessive for the purpose of having a quarantine tank for new or sick fish.

So my recommendation is for you to make sure you have a 10 gallon on hand. I have a few favorites and will place an Amazon link here (10 Gallon Aquarium Kit) for one that i really like because it is an aquarium kit just in case you don’t have extra aquarium pieces to add.

There are cheaper tanks you can purchase but they won’t have all the extra accessories. I guess it all boils down to what you have and what you need.

Also feel free to check this out;  recommended page for aquarium kits.

The Purpose of a Freshwater Quarantine Tank

A quarantine tank for fish is typically set up and maintained for a couple of different reasons.

New Fish: To quarantine newly purchased fish for a period of time to ensure the fish are not sick or are carrying any types of harmful parasites that would infect the inhabitants of your main tank.

How Long Do You Quarantine New Fish

My suggestion is to quarantine new fish for a minimum of two weeks. This might sound like a long time to you if you are new to the hobby. Some experienced aquarium owners will suggest quarantining your new fish for as long as 4 to 6 weeks.

Two weeks should give any diseases the fish might be carrying time to pop up. If by chance your new fish does show symptoms of some sort of fish disease then your quarantine tank now turns into a hospital tank and treatment can begin immediately without ever putting your fish in the main tank in danger.

How Long Do You Quarantine Sick Fish?  


A sick tank or a hospital tank is also another type of quarantine tank. This tank is utilized when you find you have a sick fish in your main aquarium. You would transfer the sick fish into the hospital tank quickly before it infected any other fish.

Once you feel confident you have correctly identified the issue you can start treating with the appropriate medicine.

That is the beauty of having a quarantine/hospital tank because if you didn’t have one set up and running ready to be used what would you do?

Well, you would have to treat the sick fish in the main tank. It is definitely possible and has been done many times before. Some things or dangers to be aware of are when medicating for one fish in the tank you are medicating all of the residents of the aquarium.

Some fish may not respond well to the medicine. If you have invertebrates the medicine you are using might harm or even kill them. Some medicines will hurt the healthy living bacteria in your filter that keeps your ecosystem running healthily.

Another issue I have seen before is that sick fish are usually picked on by the other fish eventually picking at them enough that the fish ends up dying. You eliminate those issues if you have a quarantine tank ready to go.

Do I Need To Quarantine New Fish?

If you are serious about keeping your pet fish healthy safe and happy then you will want to quarantine new fish.

The only time I would say go ahead and not quarantine fish is when you are getting them from a friend who has a healthy established tank and you know there hasn’t been any recent sickness in the aquarium, otherwise please quarantine new fish.

Fish Quarantine Procedure – How To Quarantine Fish

For new fish as recommended above I suggest keeping your new fish quarantined for a minimum of two weeks before placing them in your main tank.

For sick fish make sure to get the fish out of your main tank into the sick/quarantine tank ASAP. Once you have identified the issue follow the guidelines for the medication for the duration of application of the medicine to figure out how long the fish should stay in the tank.

I would go as far as adding an extra week after the fish looks healthy again just to make sure everything has cleared up.

Most Common Freshwater Fish Sickness / Disease

I am going to go out on a limb here and suggest that Ich is the most common freshwater fish disease.

This isn’t the article to go into detail on what Ich is however commonly called white spot disease because white spots start appearing on the fish. Sometimes there are so many spots that form it looks like white patches.

If your fish starts getting these white spots along with the fish starting to rub against objects in the tank because of being irritated then there is a good chance it is Ich.

Medication for Ich is inexpensive and I would highly recommend you have medicine for Ich on hand.

You can order it online from Amazon which I will place a link for here the Ich aquarium medication.

One last super important tip before you go and set up your 10 gallon aquarium.

Make sure you test the waters parameters like ammonia, nitrite and nitrates just like you do your main aquarium. If you don’t test your main aquariums levels you should be. Your Quarantine tank should be running at the same water parameters as your main aquarium.

Good Luck!

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