Just because he eats whenever you feed, don't feed so much. 3 times a day is way too much. Those without high energy fish like anthias easily feed once every day or two with good success. Your nitrate levels and phosphates likely are not good with that much frozen cube food going into the tank every day. Your other fish will also benefit from a more varied diet that includes vegetable matter.
"Life may not be the party we hoped for but while we are here we might as well dance!"