My wife and I are planning to put in a pond on our property, so I'm trying figure out how large we should make it, which somewhat depends on what fish we plan to purchase. We have about 2.5 acres on which to put it, though we want to put in a garden and have livestock so the pond will take up a fraction of that space. We have considered making it a swimming pond, so it potentially could be pool-depth. We live in Hollister California, which is about an hour south of San Jose. Temperatures get to the high 90s (occasionally into the 100s) in the peak of summer. In the winter, night times can sometimes get into the 30s, but it does not snow. My wife wants Koi fish but I would personally like something larger and less common. From what I've read, Koi are considered to be coldwater fish, and I think our proposed pond would be considered a cold-water pond due to the winter temperatures, even though it does not get extremely cold where we live. I've read that Chinese High-Fin Banded Sharks and Channel Catfish would possibly be compatible, but are there any other species to consider? Most other large freshwater fish I've read about are either illegal in CA, need warmer water, or are something like the Goonch Catfish (which would be super cool to have but I'm not sure they would do well in a pond and would probably eat the Koi). What are your thoughts? Thanks