I am convinced that we know practically nothing about the longevity of most fish, and the "5-10 years" boilerplate we get is severely underestimating their potential lifespan. The average hobbyist is not going to keep the same fish for over two decades, and even if they did, the odds of a heater malfunction, power outage or transport accident doing the fish in is far greater than natural causes.
See, for example, cories: the internet says 10 years, but they still make it to their second decade with some regularity (it helps that cories are some of the most popular fish on the planet, increasing the odds of somebody keeping the same animal for so long). Same deal with Synodontis: internet says 10-15 years, individual reports say 25 at a minimum. Raphael cats? 10-15 years according to the internet, likely over half a century in reality. Small plecos get 7-10 years, until you find a report on PCF saying theirs lived twice as long... and this is with tiny sample sizes, so it's likely the actual maximum lifespan is even longer.
Nobody does comprehensive studies on fish lifespans in captivity, so the internet results are derived from blog writers taking a wild guess on ages. "Small tetra? 5-7 years sounds about right. Catfish? These are long-lived, let's say 10-15 years." and so on.
In any case, great job on taking care of that leporinus, and here's hoping that he's got a good many years ahead of him.
