Well it kinda depends on the anthias you pick. Some are easier than others. As you may remember I lost my first squareback anthias last year in the 125g 2011 plague....whether it ate or not may not have mattered. But I know that fish didn't eat a thing when i had him and I am sure that contributed to his death.
Now the female squareback I have now does not eat anything but forzen food. No flake or pellets for her. It's been at least a month since I've had her and she just refuses to eat anything else. The male is all about any food that goes in the tank, he even skims the top of the water to get food before it sinks, like pellets and flakes. But he wasn't always that way, first few months all he ate was frozen. :-(
You also have to feed anthias's a few times a day, one large feeding isnt as good as 3 small ones.
I think I am going to get at least one more female anthias, maybe 2...I know the tank can handle the fish just wanna be sure, as you've probably read I'm looking at a butterfly fish too.
Sorry for the long post! LOL