Been doing a few more of these lately as there are the new wave amongst some of my clients.
Typical scenario is fish disappearing and no idea of what is the cause. Few things that I have found
that might help others...tracks trails and scats usually help identify the culprit. In my area raccoon
are my most common culprits. But have also had house/feral cats, herons, egrets, crows and mink.
Has anyone else dealt with these artificial ponds before and have you ever had great horned owls as
the predator?

I've done a few pond jobs. For coons and herons the pond can be made deeper or an enclosure.
Another simply fix for birds is to lay pieces of drift wood across the pond about 18-24" apart. Really simple and looks pretty nice too.

Mchewk

Lot of customers build these koi ponds and as a afterthought begin thinking about keeping keeping birds and animals out. Its amazing they will spend 25,000 on a rare koi fish and not a few grand to build them a safer koi pond. I did a podcast back in 2009 with Reginald Murray of OK http://www.blubrry.com/wildlifecontrol/386072/protecting-koi-ponds-from-wildlife/

I have also included a link to a site with a few tips. http://www.scottsaquaticcreations.com/protecting_your_koi

Great blue herons are major culprits around here.

Thanks guys. Question....some koi are good sized fish...common sense tells me that IF a small animal like a mink kills a koi there SHOULD be blood scales pieces behind at the kill site?? Anybody have any insights?

MChewk. yes there should be, but mink watch CSI. They rarely even leave their paw prints. And it's not just one mink. I had at least three mink work over a pond and not one of them left any evidence. The only reason that I know is because they were all females and once we caught them all, the carnage stopped. But only until the next mink came along. And then you have blue herons, raccoons, and God forbid, an otter.

Yep Paul that is what I have suspected but can't verify it. any chance an owl would have a taste for koi?

What type of trap set up did you use to target the mink? I've tried several different things around Koi ponds with limited success.

Gary

I've used Conibears, footholds, and cages. Sometimes you win and sometimes you lose. The females are lot easier to catch than the big males because you don't have to wait a week or ten days for them to come back.