Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
It does not matter if you are running a $5 millon set up or a $50.00 set up- Keeping the existing fish safe, and not having to medicate the display tank are very good reasons to quarantine new fish. You might have fish or shrimp in the main tank that cannot tolerate the treatment that the new fish need, or are particularly susceptible to certain diseases.
The Q-tank ought to be low stress for the fish, which generally means hiding places, shade from the light, and (of course) high quality water. You need to be able to see the fish, so a couple of rocks and some drifting plant trimmings is plenty.
Bare bottom need not be stressful, put something dark under the tank, or put a light scattering of fine gravel or coarse sand on the bottom.
A month of quarantine will show most of the common diseases (Columnaris) and parasites (Ich) that show up on store-bought fish. Longer probably won't show some of the slowest moving diseases (Mycobacteriosis).
It gives you a chance to medicate for internal parasites. You can add a UV sterilizer for several days or a week if you suspect Ich or other problems. But turn it off before you start the 1 month quarantine after these meds are cleared from the water, and after turning off the UV. Do not combine UV and meds- the UV may deactivate the meds.
I disagree about the water.
Test the water in the bag for GH, KH, TDS, pH.
Set up the Q-tank with water that matches these parameters. This is easy- when you plan to get fish set up the Q-tank with fairly soft water. When you get the fish and test the water they are in you can add minerals etc. to match the water.
During the month the fish are in the Q-tank you can do plenty of water changes to gradually alter the conditions to match the display tank. This slow acclimation allows the fish to alter their metabolism to deal with the altered water parameters.
This specifically includes CO2- Many of us with planted tanks are running a lot of CO2. Fish are OK with this, but usually need some acclimation to it. You should not add new fish to a tank running high levels of CO2.