They don't do well in captivity. They typically won't eat and will starve within a month. On the rare occasion, one will survive but two years is about the max. They have been known to live longer when kept in pairs (if you can get two to eat).
In the wild, they live around 20 years.
Most online retailers typically show an amazingly beautiful blue and yellow adult male. But then they state that they'll ship you a juvenile (typical). Juveniles are pitch black.