Missing fish

Question:

Missing fish I had 20-25 fish in my pond,some bought from you all, and have had it for over 7 years with no major problems. It has seemed to be predator proof as I keep a net on it and have steep sides with rocks and have it deep with places for the fish to hide. Sometime this past week most of the fish dissappeared. I have 5 left. The biggest are gone. 5 koi 14 to1 7 inches long, 2 golden orfes about 12 inches and a number of larger shubunkins,serasas etc. The 5 left are 2 plain goldfish of medium size and 3 very small fish born this season. Otherwise empty with no signs at all of the missing fish. I had a net over the top to keep leaves out. The pond is 3 feet deep and has many rocks to hide in. The net is still intact and the rocks around the edges are not disturbed – as normally happens when a predator has tried to get in. I am really baffled. I can’t imagine a predator getting that many in so short a time and not having the net disturbed or any other signs. Any ideas or similar reports?