"kuyper" wrote:

While nature is able keep a small population imbalance in check, I'm
sure it couldn't handle a large one. If I start out with too many fish
and not enough food sources, they will starve. Can you give me any
rules of thumb for how many fish and plants of a given size and type
can be supported naturally by a pond of a given size, and in what
ratios? The rules of thumb I could find for aquaria were based upon
plants artificially supported by pumped CO2, and fish that were being
artificially fed. They assumed that the fish weren't eating the
plants, and that the plants were being trimmed by the aquarium keeper.
As a result, those densities are way too high for the approximately
balanced ecosystem I'd like to set up.

The main problem I see with setting this up is that the fish will breed,
which will bring you to your scenario of too many fish and they will starve.
If you want something natural AND low maintenance, omit the fish altogether.
Then you don't even have to be concerned about your water parameters. Along
will come the dragonflies, frogs and birds. If you have mosquitoes, you
could introduce a few gambusia that will deal with them. Of course, they
breed like guppies. Depending on where you live, the county vector
control will pick those up for you.

FWIW, I don't think there really is such a thing as low maintenance pond.

San Diego Joe
4,000 - 5,000 Gallons.
Koi, Goldfish, and RES named Colombo.