Four years ago I bought a cheap pond kit and dug a bathtub sized pond to cool off in. The next year I added plants and a huge school (flock, herd?) of comets from the feeder tank. The population was halved over the summer but the fish I set up in a winter tank were wonderful. When I put them out in spring I noticed that it seemed like every chain pet store in town had koi so I got a couple, lost one, got a couple more, lost one. Seems I have about a 50% survival rate.
That's one thing I'd like to improve for sure.

Things that are wrong with my pond: It's really much too small. The fish are small enough now but that won't last. I've not started but hope to start enlarging it this autumn and finish in spring before the fish go out.

One thing I'm hoping to do with a new pond is design it better for plants of various depths and such that the plants can be left in. I'd like things that are hardy in my zone even if they're not as flashy. I'd like to dig a corner of it under the waterfall deep enough to keep liquid and leave the fish there all season but I'm not sure if that's even possible.

Last year I kept a lily pot alive in a bucket of water with a birdbath heater in it, inside a cooler. The water hyacinth with it rotted and so did all the leaves, but I've since read that I should have pruned the lily and composted the hyacinth. this year I'll prune the lily once freezing is entrenched and I've put the birdbath heater under the waterfall rocks and the lily right by it, with the basket of bulrushes guarding it so I can perhaps insulate with snow.

I'm wondering if something of this sort in the new dug pond would allow fish to stay out at less extreme depths. I am not planning a pond much more than 60 or 70 square feet at the most. I read on one site that you need 7-8ft of depth and that just wouldn't work here. It's just a small urban garden.

Perhaps I should just focus on figuring how to fit a bigger tank into my house as the fish grow? At this size they're already getting harder to net gently enough.

View from behind the rock waterfall of my wee pond with dwarf bullrushes. In case the image fails: http://www.flickr.com/photos/annrkiszt/5498783834/

A late spring snowfall between setting up the pump and adding living things made this a very sweet view. Flickr page for this: http://www.flickr.com/photos/annrkiszt/4551930734/sizes/z/in/photostream/