I live in Western WA in Snohomish County. I have a 75" by 85" or so natural pond. I put 50 real small goldfish in it 3 years ago and 50 trout a year and a half ago. The pond is at its deepest maybe 8 feet. There is lots of natural vegetation and frogs and insects and such in it. I have never fed the fish. I very rarely see a goldfish in it, I saw one a month or so ago it was about 5 or 6 inches long. I can see trout anytime in there I got em at maybe 1 inch long and they are 4 to 6 inches now. I have many ducks and a pair of geese who live at the pond in the warmer months but leave in the winter, strangely last winter 2 ducks and 3 ducklings stayed all winter. Last winter was very mild the pond only froze for 4 days all winter. I put a large drainage pipe on side of the pond because it would spill out when it rained hard for a few days. It stays at a pretty constant level now. It has 2 very small mini water flows that flow into it. Ive never seen a dead fish but I have no idea how many are in there now. There is lots of vegetation and you cannot see if there are fish in the middle areas. Ive seen maybe 10 different trout at 1 time. Im not sure if the fish would live if we had a real cold winter but we have not had one since I stocked it.