Phyllis and Jim wrote, On 19/05/2007 18:48:
We have never tried a totally fishless pond. I suspect it would have
fewer nutrients than our koi/goldie pond as it would have less
fishwaste.

The excess nutrients come from the fish food that we throw in, it is
packed full of calories that the fish turn in to urea.
Many people have low maintenance gardens ponds with a few fish that are
never fed. There is no pumped filtration or outside intervention. The
population of fish (and plants) is self regulating depending on the
available resources. Fish eat plant matter or invertebrates so if the
pond is in balance, the nutrient level will be just right. Probably wont
be a great pond though, and fish will die if the system is unbalanced.

--
DavidM
www.djmorgan.org.uk