So the way it sound that this pond is open to a like a club???? as it seem like you do most of the work you should talk with those who are leaders and make some rules for the pond to keep it healthy like
No throughing bullheads back
No bring in other fish
No keeping cretin species or cretin size ( walleyes,Hybird strip bass,Large blue gills,Large crappies)
and make limits like only 5 pan fish and when or if they are aloud to keep the other large fish only like one fish of any species at a cretin length.