In their prime of breeding, about 2-3 years. When they are old, they look seriously like old folks. Their skin loosen up and wrinkles starts to show...weird but true.
Yeah I kind of have to agree with Musha on this. But you know what I've notice? A lot of fish with a ginormous head usually don't have that much of a strong tail. Ehh...as they say, can't have the best of both worlds right?