I have a Synodontis notatus that I got in 2002. He was nearly 10" when I got him, so he's probably 14+ years.
I also have a common pleco that I got in 2000 when he was about 4" so he's probably 13.
Finally, I have a Corydoras robinae that I got as an adult in 2002 (he's the last in a group that I had).