I think Amano's life span heavily depends on water temperature, usually it's reported they live 3-5 years but the ones I've kept in "forgotten" tank lived for more than 8 years. Tank was neglected, no artificial light, full of moss and other undemanding plants, extremely rare water changes and was moved to conservatory where temperatures in winter were way below 12C deg (and I doubt average year temp exceeded 18C deg). Majority of Amanos lived there for definitely longer than 6 years, now it's almost 9th year of that tank existence and around six months ago I was able to see a two females hiding among the moss. Now probably they all are gone, haven't seen them for some time. In "typical" tank (lots of light and plants, stable 23C deg temp for all the time) my Amanos haven't exceeded 5 years of life span.