my eldest was Peter. He was sixteen and a half, and died a few months ago from tuberculosis. One minute all the fish were swimming around happily, then in two days - *bang* - they ALL got tb, and three died, two survived. I cremated Peter on the barbecue - DON'T LAUGH - i didn't cook him, I put him in the coals and then collected his ashes the next morning and I've got him in a pot on my mantel piece. It was a very sad day...
Oldest Goldfish on record I think was one called Tilly in Yorkshire lived until 43 years of age. Her friend died at a mere 30 years. Don't ask how I know that In good conditions they can easily reach 20-25 years.
snotirl there is a little pellet inside the fishes head that gets bigger with every year and after they die you can cut them open and find it and count the rings. however it is very timy and in a goldfish its only about the size of a grain of sand.