i would stand them upright when placing them if it were me. it might be too dark if you put them on their side. i don't think game fish do much in total darkness.
i keep a cage hanging off the side of my dock at all times. it is about 4ft square. small bluegill go thru the 3/4" mesh to avoid predators and to feed. i keep a feeder ring in there at all times so i can hand feed them. they stay long enough in there that they can't get back out. all of the fish in the attached pic went in there on their own when they were fry.
