Dude...he looks good! If it doesn't want to eat, then it doesn't want to eat.
i would start reading everything you can on caring for Sebae anemones. But, I wouldn't implement any "advice" until you develop a common "theme" from multiple sources.
Generally speaking, excellent and consistent water chemistry, appropriate lighting, and appropriate water flow, are going to be the primary factors of success with anemones and corals. And, appropriate doesn't usually mean, "as much as financially possible". Food is easily 3rd in line when trying to "troubleshoot" what could be wrong.
Also, be vigilant, with protecting it from any kind of internal intake screens, or power heads/pumps. Almost always, it is never a matter of "if", but "when" an anemone will get sucked into one.
Your picture doesn't show anything could be wrong at this point.
Good luck (effort) with him!