This is prolly the main reason I have no expensive fish out there, I didn't pay more than one dollar for any of them, but I do get attached after awhile!
Another thing, goldfish, well, they are pretty stupid

Thats why I admire 1 of my guys out there, Big Red, my oldest 6-7 yrs old prolly. He has survived every attack by critters his entire life, so he must be smarter than most. I did find a few of my others that I like, but I'm not sure on their sex. I was only sure on Mrs. dot just this spring when i saw she was packing eggs.
This is one more reason i over winter some goldfish babies every year, as soon as I think it's getting a bit crowded out there, WHAM, a critter comes along and makes sure there's no over-crowding!
Cue up Elton John "It's the Circle of Life..."