No, best to leave the QT wo any substrate; in the event that you need to medicate your fish due to disease, then a substrate-less treatment tank is better [ie: some medications are absorbed by the porous substrate, making maintaining therapeutic doses during treatment difficult.
Paint the bottom of the tank [on the outside] black or blue. This reduces the reflectiveness of the substrate-less tank. Add fake coral decor and/or PVC pipe for “housing” of the fish. You can add a paper background on the back of the tank, or paint it as well [on the outside of the tank].