Hi All, I don't think I've ever seen this asked before.
When we first were going to create a pond we were at Lowes and
checking on possible liner materials. The clerk asked us if we were
building a koi pond. I said, that is one possibility, and.........came
home and looked up Koi. Had never heard the word before. We decided
on Koi as the books said goldfish usually only live an average of 6
years and koi can go 60 years or longer.

While Koi supposedly CAN live that long, my personal experience has been in
the ~6 yr range - they seem to be more finicky about water parameters than
GF, which to me seem to be bullet proof compared to koi - I currently have 2
BF Koi, one 4 yrs old (16") and one 2 yrs old (5"). What you feed koi (I use
a mid-grade koi/GF food ) might also have a lot to do with their life span
as well as the proper sized pond (depth)
Gale :~)