What I wanted help with is that I have a mandarin. Should I leave him inside the DT or should I pull him out also and treat with copper or tank transfer method. Your help would be greatly appreciated.
If your plan is to go fallow in the DT, then you don't have the option of leaving the mandarin in the DT - he has to come out.
I've got a mandarin in QT now (and have since the start of the month). I've found two options that seem the most viable:
Frozen Cyclopod+
This is what I use. When I drop a cube into the QT (10gal), I can see the cyclopods mix into the water. I monitor their density and add a cube as needed (about every other day, or after a transfer).
Live Copepods
I've picked up a few bottles of the Tisbe pods and added them into my DT. I had some in my QT before I started TT, but once I started that, I didn't want to be spending that much on food. Once you are done with TT and into a long-term QT, this might be viable, but note that there won't be much food for the pods in a QT tank, so you would have to be dosing in something they could eat...
Every individual mandarin is different, however, so what is working for me might not for you. Another option/variation is a
"Paul B feeder" and some brine shrimp (I tried this, but my mandarin ignored the feeder completely).
FWIW; I would suggest the TT method. It worked (is working, really) for me and seems less error prone than copper. Just my (inexperienced) opinion.
