Setting up a QT does not have to be expensive or complicated. The saying “simple is better” applies here. So, let’s first list the reasons why you should quarantine:
In addition to being able to treat a new fish for diseases, you are protecting your fish in the Display Tank (DT) from being infected since most fish diseases are transmissible. This group of fish may be worth hundreds, if not thousands, of dollars. Most medications (that actually work) ARE NOT reef safe.
Some diseases cannot be “managed” as ich sometimes is. Velvet (which is often mistaken for ich) can wipe out your entire fish population in less than 72 hours. Whereas flukes kills fish 1 or 2 at a time, over a period of several months.
Experiencing a “wipe out” often leads to a quick exit from the hobby. It can be a beginner just getting started, or even an experienced reefer who just can’t take it anymore. I have seen many great DIYers and coral experts walk away from this hobby because one disease after another afflicted their fish.
We all know (or will learn) that things can suddenly spiral out of control in the DT. It’s a risk we all take. Having a fish QT (or frag tank for corals) can serve as temporary housing in case a toxin contaminates your main display; or a fish fight breaks out and one fish is badly injured.
By utilizing a QT, you are able to match the salinity (SG) of the water from which a new fish came. Many LFS & online places keep their fish in low SG. Knowing what their SG is beforehand allows you to “float & release” as opposed to drip acclimation which can damage a fish if ammonia builds up and/or the SG is raised too quickly.
Light (can just be a simple, one bulb fixture)
Hang on the back (HOB) power filter, where carbon or even a “seeded” sponge (explained later) can be added
Egg crate (used on lighting panels), which can easily be cut with snips to build a custom top to prevent fish from jumping
PVC elbows (see pic below) used as “caves” in which the fish hide
Seachem Ammonia Alert badge
Substrate and rock are best avoided in QT, as those can absorb many medications. However, one or two small pieces of live rock may be added for ammonia control, so long as they are coming from a disease free tank. The live rock will need to be removed once a disease is spotted and before medications are used. Furthermore, the live rock must be considered “contaminated” once exposed to a fish disease, and left in a fallow (fish free) environment for 72 days to starve out any parasites. Or alternatively, sterilize it using a mild bleach solution; after a thorough rinsing & drying period, it can be reused as dry rock.
Toxic ammonia, caused by fish waste and uneaten food, needs to be closely monitored in QT. You can use a test kit or a Seachem Ammonia Alert badge. Even the smallest traces of ammonia are toxic! Therefore, anything other than a “0” reading is something to be concerned about! You can perform a water change to reduce ammonia; or alternatively, use an ammonia reducer such as Seachem Prime. We recommend using a hang on back filter with a "seeded" filter sponge. It is a good idea to keep these filters in your sump of your tank to have ready if you need to setup a quarantine. This will help keep ammonia levels down reducing the cycling period of your tank.