The submerged vegetation does not seem to spread and based on aerial photos for the last 20-30+ years it seems to be stable. There isn't a lot, only a patch on the inlet side, maybe 4x10'.
They are bluegill and only bluegill as far as I can tell. All I can do is assume that the few large ones are just plain old.
I was told last fall there were 5# bass in the pond but I do not believe there are any bass at all and they could have died out a decade ago. There are lots of tadpoles and frogs that just float around which would be easy snacks if there were any predators.
I believe there are a few blacknose dace or simliar fish but not in high number. I did see two distinct cloudy clusters of fry so they do spawn even with a lack of gravel.