I find it hard enough keeping one going Fidgetbones. You must really love gardening.
Verdun, I have about 15 Koi, some huge and several goldfish. I have seen a Heron once and it frightened the life out of me. I think I'm lucky that the pond is quite deep and, so far, I haven't lost any. The fish 'dive' the minute there is a shadow.
I love all my plants Verdun. I do tend to go for 'pretty' shrubs and ground cover, usually in pinkish shades. And I love my trees. I just love my garden. Simple peeps.