To be on the safe side, I would would doodle on the out side of the tank.
AJWaters, "...fish store mark the bag that hold the fish/coral with a sharpie..."
Something else to worry about:scared:
What I do is place water and fish in a small empty tank(1 g) Then put the air hose/stone, and drip line into it. My tank water brings up the temp of the store water just fine. I really never have known what contamanates the outside of the bag may have. I may be too cautious.
TR