I had to start my radiata on FW ghost shrimp. They primarily eat crustaceans in the wild. I've been told by many sources that guppies and FWfeeder fish are bad for marine fish's livers or something. Thought I was never going to get him off live foods, started planning a shrimp propagation system.
In a couple/few weeks I eventually got him to take krill on a steek as he was eating the live ones - kinda fooled him into it as first. Had to use a thin invisible acrylic rod and subtly wiggle it to gain his interest. This was all done in a QT where I had close control.
After a few weeks in the main system, he's become part of the feeding frenzy, grabbing larger mysis from the water column.
Fed him 2-3 times / week when he was eating the ghost shrimp. He would gorge and have no appetite for a couple days. Now he eats 2xday with everyone else.
He gets along fine with all his neighbors, but I wouldn't put anyone that could fit in his mouth in there with him.
Very cool fish, GOOD LUCK.