The average lifespan of a smallmouth bass is around 6-14 years. If you are going to keep a fish like that as a pet though, i would recommend a largemouth bass instead, because they tend to have a few...
at least 15 inches
Micropterus dolomieu is the latin name for smallmouth bass.
11lbs 15oz. Caught by David Hayes in 1955. The bass was taken in July from Dale Hollow Lake. KY/TN
Largemouth can get very large . . . larger than a smallmouth can.