my friends goldfish of +10 years died a few days ago. he wasnt the model goldfish owner in fact he was looking forward to this event for a long time o.O. they kept the comet goldfish in a 10gal and WC every 7-8 months or whenever the tank got too slimy. he had some neon tetras in the tank but they dissapeared into the filter or into the goldfish. there was growth stunting as he??? was only 4-6 6 inches long, is it common for goldfish to last over 10 years?