As other posters commented, it depends upon other fish in the pond, fertility, and more. It is harder to get an optimal fishery without a management plan. Bass help prevent bluegills from overpopulating and stunting by thinning numbers. Flatheads get large enough to thin (eat) your biggest bluegill and some fairly large bass. You want bluegills in your pond and not hybrid bluegill or green sunfish. Also, you want to try not harvest the biggest ones as bluegill mature at different sizes based upon competition.

Lots of pond and fisheries management information at www.pondboss.com. I found out about that forum from someone on here a few years ago and have told several on that forum about this one.