I have kept senegals with my female midas, even when they were half her size (maybe smaller) at the time. She used to push them out of her plant pot with her snout but never bit them no matter how many times they went in. This was in a 4ft bow front (roughly 70g).
She is a nice girl though and rarely bothers anything, even other cichlids, which I believe is in the minority for midas, it's really your call. I have never had any cichlid even nip at any bottom dwelling fish including snack sized loaches and bichirs.
Do you know the midas' habits because it is a friends?
What are its tankmates in its current home?
Each one is different, as are most cichlids, and only the owner knows the fish and its temperament. Other than just trying and risking a lovely bichir, that is the only other way you will find out if it will work.