Can you Oer feed a Grazier Fish

I recently purchased a Coral Beauty Angel, after learning it's a grazer
fish; me being the good LF owner, I place seaweed in the tank once a day as
well as feed him a combination of flake, Frozen brine and mysis shrimp. I
give flake on Monday Brine on Wednesday and Mysis on Friday, I'm trying to
keep his diet well rounded. My question is simple: Am i over feeding or
underfeeding him? I'm thinking I'M over feeding, the reason being, there is
usually a line of fish turd hanging from his rear end. Your thoughts are
appreciated.