I was at my aunt's house today> She has a BEAUTIFUL 15ft diameter pond that is aboout 3 feet deep on the sides and 4ft deep in the middle.. She has MAJOR issues with all types of preditors. The pond has a VERY natural look and the sides slop in, so the animals all have VERY easy access even though it is heavily planted.
She has eagles, hawks, turkey buzzards, and raccoons.
ANWAYS.. the absolute BEST way that she has found to keep all preditors away was the following.
stick 4 or 5 black medal pipes in the ground. Make sure to put caps on them so bees dont take nest inside of them.. Then use PIANO WIRE (instead of fishing line) and criss cross it across the pond.. You can't even see it. It doesnt reflect like fishing line and is a LOT stronger..
Then, in two places on the wire, hand something that will dangle and move in the wind..She used those swirly looking long wind spinners, but you can use ANYTHING that will move in even the slightest wind.. If they are shiny, its even better
The movement and shiny-ness scares them away all of the time.. before that she was loosing a fish a day. She told me that she went outside and found her biggest breeder koi ripped to shreds by a hawk. He pulled it out, placed it on a large, 4 ft tall tree stump and had a nice dinner. That is when she started putting this little idea together.
If you plant some vine type plants near the black poles, you will hardly notice them.. and the piano wire really just disappears in the the rest of the background.