I've had several large Goldfish taken from my backyard pond by invading Great Blue Heron in the past so I decided to deter them with a bunch of 10 foot PVC irrigation pipes I bought at the hardware store. It appears to have worked because after this video they have not returned.
I lay out the pipes in the evening before dusk and take them up the next morning. I do this every night. It takes about 4 minutes to lay down the pipe and about the same time to pick them up. The pond is located in Tucson Arizona. The nearest other body of water is a small city park lake located about five miles from my house.