Fish not eating

Hey everybody, I recently aquired a Regal Angelfish last Saturday, and he is not eating at all so far. He looks to be healthy, no ick or any signs of illness, and hes swimming around fine, even though hes being rather shy and hiding in a particular spot alot of the time. He spends alot of time getting cleaned off by my peppermints. I've tried flakes, frozen brine shrimp, and even got some Angelfish and Butterfly blend frozen food. Still no go. Starting to get alittle worried because hes a REALLY nice fish and I would hate to see him die. I heard about a method of sticking him in freshwater for 6-10 minutes to get rid of parasite worms he might have, as I heard angelfish are known for that? I might be looking to try this in the next couple days if he doesnt start eating, but I just wanted to see if I could get anybody elses opinion on this. I'd really appreciate anybodys help! Thank you!