What was he eating before you got him. Maybe that is what you will have to do. Also try feeding after the lights are out.
It would take you 7-9 days for it to settle down and eat. Try dimming your light or light one side of the tank only. Feed massivores and diced up tilapia.not too sure as I never ask seller...will try lights off feeding...thks...
one more thing...this 22"PBB keep snapping at other fishes...is it normal ?...