Checking the age range of Koi by the fins...

[cocoyboy]

Hmmmm, interesting? I remember you mentioning that about some fish I bought a year ago that had thick pecs. They were suppose to be around a 18 months old? They're even thicker now! Hella old then.

[aquitori]

I think the breeder is feeling for the little bumps...I Mr.Meada did it while we were at Momotaro. They are feeling more for the sand paper like bumps that males have. If you rub long enough you may or may not feel anything.

I think JR is closer to what I was getting at. Size of the fish and skin thickness of the pecs will get you a some what range of what a fish is...