Hi! I just found this forum. When we bought our house in 1995, the previous owner had put in this wonderful pond as the centerpiece of the backyard. It had a great waterfall, but no biofilter, no UV light, which I have added as time went on. I added a few fish to the solitary white goldfish that was resident at that time, and they bred (as fish do). The population has waxed and waned, and over time become less colorful, more "carp-like". This year I decided to add in some genetic variety - a couple of Comets, a couple of Shubunkins, and a feeder goldfish. The pond is pretty balanced, although at times the fish population has skyrocketed and plummeted. I had 40 baby goldfish the year I had a water balance problem and all the big fish died - that was too many fish! I managed to donate them to someone who had a big pond that had been decimated by a heron. I love my pond, but I don't put a huge amount of work into it.