I feed lions at my LFS all the time, and you would be surprised what they fit in their guts. Its a lot for a 40 I agree.
If the fish can fit past their jaws they will eat it. Not sure they will eat a Mandarin though. They are brightly colored for a reason - the biological term is advertising. They have a poisonous slime that the lion is best advised to stay away from. They may not, which is bad news for both fish