Most fish require a few days to settle into their new surroundings. I would leave the light off for a couple of days and then begin to offer very small amounts of food, and a good variety. Nori, as mentioned, is also a great addition.
On a side note...the purpose of a QT tank is to completely isolate the contents from your main. It is risky to use LR
from the main in the QT and then put it back in the main when you are done. When I QT a new fish, I put a filter pad in the sump of main a couple of weeks before hand so it can develop the beneficial bacteria. I use it once in the QT and throw it out after my new arrival has been through a proper QT.