I have 30 LMB I moved indoors about july first last summer. These fish have survived and grown very well on nothing but pellets. A few weeks ago I was sorting out some minnows and found a few GSF about 1.5"-2", for grins I chucked them into that tank and 11 GSF disappeared in about 3 secs if that long.
You would have to breed that instinctive behavior completely out-if even possible- for them not to eat natural foods. I don't know of any research on that-never had a reason to look for it, but these fish have had nothing but pellets for 13 months yet instinctively attacked and ate those 11 GSF.
Just my experience.
EDIT: These were 3" fish when tanked, about a pound now.