What Do You Need To Set up An Aquarium Quarantine Tank?

Aquarium QT Essentials Header

You have just noticed a funny growth on one of your fish or two of your fish have been in a fight and one is badly injured. This is the time you wish you had a Quarantine Tank ready to go! For under $100 you can have a tank that can be set up and ready to go in minutes.

A simple aquarium quarantine tank can be set up using a small aquarium with a filter, heater, thermometer & PVC fittings that are all clean, and sterilized. A filter sponge already seeded in an aquarium or sump, will allow it to be set up quickly when needed.

Why Do You Need An Aquarium Quarantine Tank?

A Quarantine Tank or QT for short, is a small, simple aquarium that is used to treat, monitor, or rehabilitate a fish away from the stress of your main display tank. It should be used when purchasing any new fish or when one needs to be isolated for medication.

A QT setup can be super cheap and really simple to set up, especially if you troll the second-hand classified ads or yard sales! I set mine up for $20! It has certainly saved me that 20x over!

Quarantine Aquarium
A Simple Quarantine Aquarium Setup

For a simple QT setup I recommend the following:

  • Small 10-20 gallon aquarium. A food-grade container can also be used 😉 – Pick the size for the fish. ’20g Long’ tanks work well for swimmers!
  • Lid, mesh top or eggcrate to prevent jumping
  • Heater to suit tank size
  • Small hang-on-back filter to suit tank size
  • Replacement sponges for filter
  • Thermometer
  • Ammonia Alert Badge – You can get it at Amazon.com for cheap!
  • Large PVC fitting or two for fish hiding
  • Separate Tools – Nets, Turkey Baster, Cups, Measuring Jug etc

All quarantine tanks should be bare bottom to prevent harboring bacteria or parasites and sand is not needed. Your QT and all its equipment need to be easily cleaned at the end of the quarantine period so it’s ready to go for your next purchase or emergency.

Why Should You Quarantine New Fish?

This has been a debate in the hobby for decades and will continue for decades! There are some that say you need to quarantine and those that say it is a waste of time!

I’m in the Pro QT side because I have seen many a tank wiped out by the addition of one new fish! For the sake of a few bucks and a little of your time, it is worth the prevention!

All new fish should be quarantined to allow the owner to inspect the fish and medicate if required before it enters the main display aquarium. An unseen infection or disease can be easily spread to all the livestock of an aquarium leading to an outbreak that can be fatal for all the inhabitants.

How many Dollars worth of livestock do you have? How much hassle would it be if all your fish got a disease and died? How devastated would your daughter be if her favorite fish was lying on the sand, half-eaten when she came down in the morning? You get the picture!?

The stresses involved in being moved from ocean/growing facility to distributer, to the local fish store, to your home is immense and this could of all happened in the last few days. Many fish gets purchased as soon as it hits the store.
Some very good stores will have their own QT/rest period, but most do not!

Stress can quickly allow an invisible parasite like Ich to take hold. Your new purchase could have internal parasites. How do you know your new guy is clean? You don’t, this is why a little bit of time for your new fish or a group of new purchases is essential!

How Do You Quarantine Fish?

Fish should be kept in a separate aquarium for up to 4-8 weeks and medicated for internal parasites, bacterial infections, and diseases. They should be kept alone or in small numbers while the treatments are administered. A small, well-maintained tank is most commonly used by aquarists.

My QT Tank Ready To Go As I Need It

My method of fish quarantine is just the same as many of the other experienced aquarists. Nothing goes in my display tank unless it has been quarantined. This is the same for corals, but that’s for a different article which you can find HERE.

When I know I’m heading to the fish store will take about 6 gallons of water from my sump and then top off another 2 gallons of new salt mix into my QT which is a small 10 gallon aquarium.

I remove the filter sponge I have seeding in my sump and place it in the HOB filter, turn on the heater, add the thermometer and Ammonia Alert Badge and get the tank running and stable.

Aquaclear Filter
My Aquaclear Filter – Only Sponges Used
Aquaclear Replacement Sponges
Aquaclear Replacement Sponge 3-Pack

You can find the range of AquaClear filters & replacements foams HERE at Amazon.com.

This is the way I have done it for years and it takes me 5 minutes because everything is cleaned and ready to go from the last QT period. I always have 2 filter sponges sitting in my sump seeding with bacteria for use at a moments notice.

Every two to four days I will do a 10% water change to keep on top of the Ammonia. Having a small quarantine tank makes this a super simple job. I have 20 gallons of new salt mix always ready at my home which really helps.

Just be sure to top up the medication you take out with the water change. A bit of math is required but should be straight forward. 10% makes the numbers easy.

eg: Cupramine (See Below) in my quarantine tank requires 2 drops per gallon for the first and 3rd day, then left at that dose for 14 days. When I do a water change this would get diluted.

I use the Seachem MultiTest Copper Test Kit that I get from Amazon.com to re-dose to the recommended amount of Cupramine to maintain the optimum level. This is what Seachem advises to do so I do it and I’ve never had a problem.

How Long Do You Quarantine Fish For?

Most aquarists and manufacturers’ recommendations say a minimum of 4-8 weeks. The most common tank destroying disease to worry about is Ich. Ich has an incubation period of 30 days and is commonly activated by stress. It is a high communicable disease that is hard to stop once introduced.

The majority of medications used to treat the common fish illnesses are copper-based and copper is toxic to invertebrates and corals, hence why we use a quarantine tank to separate and medicate befor a fish is introduced or if it has to be removed from the main display tank if it becomes ill.

I always quarantine new arrivals for 30 days if there are no obvious signs of illness. If I find anything, then it takes as long as the medication regimen dictates. I only then introduce that fish to my main display tank once I am 100% happy it is disease and infection-free – So far this approach has served me very well!

Do You Need To Medicate Fish In Quarantine?

Many hobbyists quarantine all new fish and monitor them for several weeks. If no obvious signs of infection or disease appear, they add the to the main aquarium. Other aquarists like to medicate all new fish before adding to the display tank, regardless if they show any signs or not just to be safe.

I like to treat ALL my new purchases as I cannot be sure if anything is hiding internally. Because of that I treat the following medications during the 4 weeks my livestock spend in quarantine:

Seachem Cupramine (Amazon.com)
Treats diseases like Velvet and Ich

Hikari Prazipro (Amazon.com)
Treats internal parasites

I also keep a range of various other medication just in case I have to rescue a sick fish out of my own display tank or a friend has an emergency:

Methelyne Blue (Amazon.com)
Helps treat external fungal infections

Maracyn Two (Amazon.com)
Helps to treat bacterial diseases

Keep Your QT Tools Separate!

This may surprise some of you but keep a separate set of tools for use ONLY in your quarantine tank. Bacteria can live on unsterilized tools and when you place that tool in your display tank you have now possibly created a problem!

The main tools I recommend you to get for your QT are these:

  • Nets – Varying sizes for the fish being caught
  • Measuring jugs and spoons for medications
  • Glass scrubber
  • Cleaning scrubbers and toothbrushes for post QT cleaning
  • Tupperware’s for transferring livestock
  • Fish bags for acclimation
  • Airline tubing for acclimation
  • Spare heater and filter

How Do You Sanitize an Aquarium Quarantine Tank?

The important point to remember is to have your quarantine tank ready to go for when you need it, and this means it needs to be properly cleaned after each use.

A solution of white vinegar and warm water used on all the quarantine tools and tank will help clean and sterilize them. Rinsing with clean, warm water and drying will then allow the entire quarantine set up to be ready for its next use. Bleach can also be used, but must be rinsed thoroughly.

The way I clean and sterilize my QT setup is by giving EVERYTHING a bath in warm water and white vinegar. I have a deep laundry sink so I fill it and place everything to soak. Tools, nets, PVC fittings, filter, heater, you name it it’s in there.

A good scrub, lots of rinsing then drying keeps everything pristine and ready to go for the next time.

I find the vinegar works well and kills everything we need to care about in this hobby. Some people will use bleach instead, which is good too, but I find it makes me nauseous and the splashing damages clothing, towels, flooring, etc. I also worry less about making sure the vinegar is well rinsed off everything.

What To Be Aware Of With Quarantine Tanks?

Setting up a quarantine tank may seem over the top or daunting to many aquarists but it is really simple and once you have it in place you will use it all the time! To help answer some of your questions, here are some things to be aware of:

  • Be sure to buy medications suitable for saltwater. Some are made just for freshwater and you could kill your livestock if added. ALWAYS check the box!
  • Follow manufacturers’ instructions to the letter. If they say treat for 8 weeks, treat for 8 weeks! Let the meds do their work!
  • When I move my fish to my QT I don’t acclimate them as they are going into the water that was just taken from my main system. BUT, when I add them back to the display tank I ALWAYS acclimate.


The whole point on the quarantine tank is to isolate an animal and its potential problems. Do not add those problems to your display tank when you acclimate!

  • Keep your fish bags from the store and sanitize them for use in acclimating your fish back to the display tank.


Setting up a quarantine tank is simple and cheap to do. You can set it up in a room away from your main display and let the fish get ready.

Whether you are quarantining a new purchase or treating a sick fish, the little bit of time and effort you put in will pay off. Yes, there are times when fish do not survive the quarantine period, but that was just meant to be.

If a fish couldn’t survive the QT period then there is a reason. I want that reason to die in the quarantine tank than to find out the reason after all the rest of my fish are infected!

I always try and make my quarantine period as stress-free as possible and I find that by the end they are excited to see the person that feeds them, which then continues once in my display tank. My aquarium inhabitants are a member of my family and seeing them happy and thriving is what gives me joy.

Further Reading

You find some helpful information in the following articles: