After having Koi for over 30 years, one mean old blue heron cleaned me out!
I lost 32 Koi...some over 30 years old, and over 30" long.
My dog, Gracie, a Great Pyrenees, used to scare predators off, but some unnamed neighbor notified noise abatement and I got a letter from the city saying that, after two more warnings and stiff fines, they would take the dog (must be a new neighbor-Ive had the dog for 6 years, with no complaints).
Anyway, watch out for Heron if you have a pond. I'm researching ways to protect from them now. The replacement cost of the fish is over $10,000.00.
If you don't think you can miss fish or be sad when you lose them, YOU'RE WRONG!
Russ (fishless) Lay