Cichlidiot wrote:

Here's a potentially radical idea. How about tolerating the birds and
designing a way for them to gravitate towards the far more replaceable
fish (and less emotionally attached) than the expensive koi? The best
design I've seen so far is a deep, vertically flat sided pond fed by a
long, shallow stream/waterfall at a public koi pond. The stream was

Sounds good.

teaming with mosquito fish, crayfish and occasionally goldfish fry. The
herons almost always ate from there instead of attempting to get anything
in the main pond because they could wade into the stream and have pretty
easy pickings. Loosing those kind of fish wasn't a big deal (although I
suppose losing too many mosquito fish could be a problem in mosquito
season, but it's easy to get more).

Not likely to be a problem. I've never seen mosquito larvae or even many
mosquitos around my ponds. Koi and Goldfish are quite happy to eat them
too.

The only koi lost was due to human
problems when a teen threw a stepping stone from the garden into the pond
and it hit a koi.

Remove stone, tie round teenager's neck, repeat...

The stream served a second purpose too. It was planted with milfoil and
other plants, so it acted as a vegetative filter.

I've done that. It requires vigilance, though. That milfoil has a tendency
to dam the whole stream.

--
derek