Disgraced investment banker and husband of PR queen Roxy Jacenko, Oliver Curtis, was locked down for 24 hours after an altercation with an inmate.
The Daily Telegraph reports that last month a buffed up Curtis squared up to a fellow prisoner who was ranting at him.
Another inmate stepped in to calm the situation before all three were placed in lock down in their cells.
A Corrective Services NSW spokeswoman said no one was injured.
It was out of character for the 31-year-old who has managed to behave during his one-year sentence over a $1.4 million insider-trading scheme.
Curtis has used his sentence to work on his physique and his increased muscle mass has even earned him a new nickname.
“He is pretty popular and the inmates have even given him a nickname, Adonis, because of his ripped muscles,” a prison source told the Daily Telegraph.