I remember growing up occasionally swimming in fresh water lakes, and how exhilarating it was. Places like Lake of the Ozarks, where my uncle had a cabin......it was heaven. No one would call that a "swimming pond", but the swimming was sensational. And other lakes, those places were full of fish. So honestly, I have to say that what I'm looking for is just the cleanest, nicest water it's reasonable to have. That's all. I realize I'll have to compromise....I'm already seeing that compromise is a big part of having a pond; you can't have everything perfect.