The quarantine tank, a dilemma for hobbyists in so many cases when it really shouldn't be.  If you are questioning whether or not to set up and use a QT tank, don't. The answer is easy and will always be YES. If not for your pocketbook, do it for your fish.

What Is A Quarantine (QT) Tank?

A separate aquarium, independent of your display tank that is used to isolate, observe and treat sick fish.  The idea is to use a QT for all new fish before they go into your display so you can effectively eliminate or at least drastically reduce the risk of spreading disease. Should you notice a parasite or disease does exist in your display tank, the QT can also be used to isolate and treat the affected animals.

Do I need A Quarantine Tank?

Yes, a QT is going to save you time, money, and frustration. It is in the best interest of your fish and is the most responsible approach to keeping a saltwater aquarium. You are guaranteed to increase your chances of success and it will likely keep you in the aquarium hobby much longer. The #1 reason hobbyists quit the hobby is because of a failed tank, often on the part of sick fish.

All saltwater hobbyists will eventually encounter a problem a QT tank could have cured or avoided, there really is no escaping that. Even if you have a reputable source (online or local fish store) that practices a strict quarantine protocol for you, isolating the fish for the first 30 days (at minimum) in a QT tank at home is going to be the best practice in protecting your otherwise healthy display tank. All it takes is one, microscopic pathogen, free-floating in a tiny droplet of water to contaminant your tank. That means using the same fishnet or sharing a maintenance tool poses a risk. There is even evidence of aerosol transmission of disease between aquariums.

We will admit, it can be a pain and will cost a little money to build and maintain a QT tank which is a big reason the topic has long been ignored or debated among the community. Facts are, it's just the right thing to do for the health of your fish and the future of your tank.

What Needs To Be Quarantined?

For all intents and purposes, a QT tank is specifically for fish. Corals and invertebrates are not the usual targets for QT because they pose a much lower risk that can be throttled with alternative measures. That said, some hobbyists QT everything. Maintaining multiple QT tanks at any given time for different animals and different treatments is not incredibly uncommon for the most dedicated of hobbyists.

For the most part, fish diseases cannot infect invertebrates like corals, crabs, and snails which is why the risk is lower. The water inside their shells and bodies, however, can transfer pathogens. Corals specifically are treated via coral dips to help drastically reduce their own set of pesky hitchhikers. 

Two Methods Of Fish Quarantine

There are two different approaches to a fish-only quarantine system.  Use a cycled QT system that houses beneficial bacteria to help eliminate toxic ammonia or you can set up an uncycled QT tank that relies upon water changes and ammonia detoxifiers to eliminate the risk of ammonia. 

Cycled Quarantine 

These tanks will use bacteria, just like your display aquarium, to break down and process ammonia from fish waste. The downside is the aragonite-based reef rock or biological filter media can absorb medications and harbor pathogens. You will also be limited to certain medications because some stronger anti-biotic medications will kill the beneficial bacteria or biofilter. 

Uncycled Quarantine

An uncycled QT does not have sufficient levels of beneficial bacteria to eliminate ammonia from fish waste. These QT tanks will be safe for use with all fish medications but will require frequent water testing and close monitoring of ammonia levels. You will need to perform daily water changes to remove the ammonia and/or use ammonia detoxifying additives to help reduce the risk.  

How Big Does A QT Need To Be?

20-40 gallons is the most common QT tank size. If you only keep smaller nano-size fish, you can get away with a 10-gallon tank. Conversely, if your planning on larger, show-size fish your going to want something in the 40-60 gallon range.

 How Long Do I Need To QT A Fish?

The real answer here is, however long it takes to treat them. The absolute minimum is 21 - 28 days observed disease-free. If even a single fish is observed showing signs of illness, you need to treat the entire population. Once the signs of illness are gone, the clock starts over. So the process could potentially last a few months should you encounter persistent problems. 

Essential Equipment For A Successful Quarantine Tank

  1. Glass or acrylic aquarium - 10-40 gallons in size; any old tank will do
  2. Heater - maintain stable water temperature
  3. Filter - Hang on power filter, internal power filter, sponge filter, or canister filter will work
  4. Gravel vacuum or siphon - to perform water changes
  5. Light - somewhat optional but helps acclimate to aquarium life and makes for easy observation
  6. PVC pipe fittings or plastic decor - provide comfort and hiding places for fish
  7. Mesh screen lid - prevent fish from jumping out