esshup says - "If the pond will be used as a swimming pond I wouldn't stock the Specklebelly Sunfish"..
Okay this is a good comment and idea depending on several items. For SBS - A lot is still not well known about the main behaviors of the specklebelly sunfishes(SBS). Regular HBG with the aggressive green sunfish(GSF) genetics do have a reputation for nipping swimmers.
Usually when BG are well fed there is minimal if any nipping of swimmers. I think that it will take several to numerous generations for the BG behavior to display itself as the gene pool becomes skewed toward BG if that even happens. Again not a lot is known yet about the later generations of SBS.
Just about every panfish including small 3"-5" YP when real hungry, starving, and over crowded will get brave enough to nibble on body parts of swimmers. GSF and regular HBG(BGXGSF) are the worst nibblers and have been known to scrape skin hard enough to draw a little blood. RES are the least likely and least reported to nibble swimmers. Girls and ladies especially really do not like this nibbling from fish. Nibbling from sunfish seems to happen most frequently when the swimmer is idle with appendages dangling in the water. When sunfish are spawning, those males guarding the nest will sometimes defensively bump swimmers wading the the nesting area.
Historically my family never had trouble with plain ordinary BG nipping us while swimming. This last Summer, while doing work in the pond with BGxRES, I was nipped quite often while sitting on a piece of structure to tie a new locating float to it. I didn't get nipped while swimming or walking in the pond, just while staying still.