We have lost some of the gold fish/shabunkin too, thank goodness not our koi..but my beau strung some parallel lengths wire 6-8 in apart, over the pond..he says 2 ft OFF the ground, and we seem to have stopped whatever it was..we assumed a bird, crane but maybe a hawk. It looks a bit like a concentration camp but you can use fishing line too. The birds won't try to go through any space smaller than their wing span so..try that maybe ? Sorry for your loss..we were pretty distressed too..

Hey there. I have a middlin' size pond, 1000 gallons, and the birds in the day time and the raccoons at night certainly put me on a learning curve. I'm sure there are some other critters out there anxious to get their share of the fishies too. The best results I have had are with the Scarecrow water cannon and a bird net stretched over a six sided gazebo frame. I use only the top of the frame and actually it doesn't look all that bad. I also put out two heron statues to tell the other herons that a pair has this area staked out. I don't know if any of this if helpful to you but the scarecrow has caused a lot of laughs and the preditors slink away without dinner. Sandy

There are plans for a do it yourself water cannon on this site, cheaper than the scarecrow. Some very good tips too.

Here is a link that might be useful: Heronizer

The Scarecrow water cannon might work on the hawk. Didn't on my heron though. For herons, I like the fact that his design has the water shooting out straighter. I think half the problem with our bird was that he wasn't getting it full in the face and body - most of the water shot over him so he tolerated it. I don't know what landscapers mesh is. Have you tried covering the pond with bird netting?