You usually don't see them that large cause most peeps don't keep them long enough. But yeah they can get that large in captivity. I know Taz has a cincta that gets 20+ and his is at 16" right now I believe, in I think a 150 or something like that. They grow fast. Like I said he will definitely out grow those dats. Especially that one in pic 2, I am suprised it hasn't tried to eat him or kill him trying. My Marmorata killed two silver dollars, a V. Argentea and a V. Regani trying to eat them, and there was no way she could have swallowed them.