+1.
I think the idea of feeding once a day may have followed over from the Freshwater side of things as well. That and the days of when people accidentally dumped the entire bottle of Tetra flakes into the Goldfish Bowl. LOL.
And as Mr. Tusk said, the days of Undergravel filters and a lack of Useful, correct information about fish biology and aquarium chemistry (nitrogen cylce), where fish were oft lost to too much uneaten food and back when "fish would only grow to the size of the tank" so the 4 gallon hexagon tank would be perfect for a Jack Dempsey(FW) or a Coral Grouper(SW).
Anthias are all day eaters. The Fathead is bulkier than other Pseudanthias spp. and belongs to a different Genus all-together, the Serranocirrhitus genus. Having a fuge is a good thing as they need copepods/amphipods. Anthias like Bartletts, Lyretail, etc (Pseuadanthias spp.) if i remember correctly are planktivores, in the wild eating phyto- and zoo- planktons continuously through out the day. So I think an increase in the number of times throughout the day you feed, and perhaps a decrease in each portion size, might be helpful. Perhaps an autofeeder for the time while you are out of the house.
They do prefer dim, dark, deep tanks, usually bottom level fish. Good Luck!!!!
BTW, is it Reef or FOWLR? Has he taken to any of the food items you've offered with gust? If the mysis isnt PE Mysis, I would try those, or the combo pack of PE Mysis and Cyclo-peeze. Another secret weapon is Ova, but its not carried everywhere.
I think i might have been there when you bought this fish..... PM me.
::EDIT:: Oops. I just reiterated everything that was already said throughout the thread. Apologies.