naso tang will not eat. could it be QT tank too small?

[Gregs]

just bought a naso tang on march 31st. healthy guy maybe 3-4" in size. At the LFS he was very active amongst the group of others and was the only one interested in pecking at a piece of live rock. I put him into a 33g QT tank. parameters are ideal. he is looking very good, active, full colors. but he will not eat.
ive tried:
mysis shrimp
clam
nori
green seaweed
spirulina algea wafer
lettuce
carrot
cucumber
an assortment of pellets/flakes

with and without garlic (havent tried selcon).

he looks for food/pecks at nothing on live rock... but will not eat any food floating around.
im wondering if the size of the tank is causing him to actually be mildly stressed and not interested in any food. debating about throwing him into the 220g display prematurely.
starting to worry as his stomach is begging to look a little depleted

any advice?
the only factor i see is perhaps the nori wasnt fresh. so i will try a new batch later today...