Setting Up A Fish Quarantine Tank For Beginners

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!

A small aquarium, filter, heater, thermometer & PVC pipe fittings make great fish quarantine tanks. A filter sponge seeding in the sump makes for quick set up of the quarantine tank when required. Hikari Prazipro, Seachem Cupramine, Methelyne Blue & Erythromycin are great medications for quarantine.

This article will show you how you can set up your own QT tank for little cost and have it ready to go at a moment’s notice base on my own system that I have used for years with great success and very little cost.

Read on to see how…

What Is A Fish Quarantine Tank?

A Quarantine Tank or QT for short is a small, simple tank that is used to treat, monitor or rehabilitate a fish away from the stress of your main display tank.

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

A Simple Fish Quarantine Tank Consists of:

  • Small 10-20 gallon aquarium. 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
  • Large PVC fitting or two for hiding
  • Separate QT Tools – Nets, Turkey Baster, Cups, Measuring Jug

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 Aquarium 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!

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 Aquarium Fish?

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.

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.

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

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 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 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 To Quarantine Aquarium Fish For?

Most recommendations say a minimum of 4-6 weeks. The most common tank destroying disease we worry about is Ich or Velvet. Ich has an incubation period of 30 days and is commonly activated by stress. It is a high communicable disease which is why it can wipe out your tank.

The majority of medications used to treat the most common illnesses are copper-based and copper is toxic to invertebrates, hence why we need a separate place to be able to medicate.

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.

Do You Need To Medicate Fish In Quarantine?

Many hobbyists use the new fish quarantine as a fallow period and only treat if they notice any symptoms. I like to treat all my new additions regardless because I cannot see what they may be carrying.

I treat the following medications during the 4 weeks in quarantine:

  • Methylene Blue (About $8 at – Helps treat external fungal infections

Tools Require For A Fish Quarantine Tank

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
My QT Setup Next To My Frag Tank

How To Sanitize Your Quarantine Aquarium

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.

The way I do this 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.

Things To Be Aware Of With Fish Quarantine Tanks

Be sure to buy medications suitable for saltwater. Some are made just for freshwater and you could kill your livestock if added.

Follow manufacturer’s 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 as they are going into the water 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.

To Finish

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.


Hi, I'm Richard and I have been an avid aquarist for over 30 years with a passion for Saltwater Aquariums. I love to pass on my knowledge to help others get the same amount a pleasure out of this hobby as I do. View my About Me page to find out more about me & my mixed reef aquarium.

Recent Posts