I have a waterfall that flows into a 1000 gallon pond. I did have several gold fish that had survived going on five years. They had grown to their maximum size for my pond and were very friendly, loved to let you pet them when it was feeding time. Unfortunately, a blue heron finally found them and within a couple of days wiped them out. I've added more, but they are small. I've had my pond going on 5 years this summer. Hope to be able to share my experiences and gain helpful advice too.