Offer him food now. He may not take it, but that's nothin to worry about too much. You said you just bought him, so, it may take a few days for him to settle in, and get back on track. offer food on a regular schedule, and change it up a bit as to what you are offering. Once he is hungry enough, he will go after it. But for now, offer as normal, and if he just isn't interested, remove the left overs from the tank, and just try again later. A pain I know, but sometimes they get so stressed, it throws them for a loop and they have to re-adjust. Keep an eye on him though if his appetite does not return within a few days or so, and watch his activity closely. keep us posted.
--Emi