Well my first fish that i was responsible for caring for were 3 playts from about 10 years ago and i still like to brag that i have decendants from them in my tanks.
My oldest fish right now is a 4 year old pearl gourami (well, i've had him 4 years) pretty hardy bugger, survived my grossly overpopulated 10 gallon till i got my 29, poor guy, starting to show a bit of age, same with my 4 year old platy.