There are a number of companies around here with rather large ponds and the geese, seaguls and ducks just love those ponds, until they start roaming the roads aroud the ponds ...... a few well placed stuffed full size coyotes seem to work well at keeping the birds away from certain areas.
I have a fox mount would that work? Seriously I think I am going to try fish line. I can't use the rubber frog because the big butterfly koi eats frogs, that would not be good.
Could also try some reflective tape around the pond, a company next door to mine has coyote cut outs and poles with reflective tape to keep geese away.
I found one of the bodies from the initial attack, damn bird killed a fish and didn't eat it. I made some stainless stakes and tied in some heavy fishing line to make a grid over the pond. Going koi shopping this morning with my wife for some replacements. I picked a few up yesterday but did not buck up for the $300 koi I will buy the 4-6" and let them grow.