I've yet to see too many people keep them in cold water like they like, and they're EXTREMELY sensitive to water quality. I've seen some bigger ones (around 1ft long) in warmwater aquariums with good water quality, but not sure if they were already aquired large or whether they would end up living long enough to reach the size in the pictures.
Even when in kept in the proper enviroment some of them still die, presumably because of poor handling during shipping or just not a very hardy specimen.