What is known
A redtail is a slow-maturing, long-lived fish. Captive adults at nine years old are still growing and nowhere near the end of a natural life. Public aquariums have kept redtails for decades, many of them donated adults.
What shortens a redtail's life is almost always the keeping: low oxygen, a poor diet, a tank it outgrew, or a power cut on a big system. Get those right and plan for a fish that outlives a car loan.
Help answer it
If you have kept a redtail for ten years or more, or know an aquarium that has, we want to hear about it. A dated photo and a length is enough to start. This is exactly what keeper journals are for.