I think it could go with some convict, and I think a 55g would be the minum tank size for a half grown adult.
i dont know about cramping your fish...but just like us humans we need space to venture and relax...if not we be stressed and bangin our heads to the closest thing available.. like the fish trapped in a small glass or acrylic tank tryin to find its' way out...well eventually will stress out and die.. but eventough its all about the health of the fish and not its happiness...you can put a FH's in a small tank even adult just u need to keep the water very clean, with a good filter/filters, and give them a few marbles there happy ... You do know they like pitchin marbles