As true as the fish feels! If he's hungry, offer him one pellet (the type you will ALWAYS be feeding him, no treats) for now, see if he eats. If he does, yay! If not, remove it.
I believe fish that have been shipped/imported shouldnt be fed because theyre so stressed it can cause bloat.
But hey, try it :) Try giving him (normally) 3-4 a day, spaced out, not all at once.