Diddy Prison Fight: Former Rikers Island Warden Says Brawl Could Impact Release Date

Diddy's recent prison fight could end up undoing some of the good behavior credit he's already racked up ... so says the former warden of Rikers Island.

Howard Robertson -- a former New York City Department of Correction employee who rose to the top job at one of New York's most notorious federal pens -- joined us on "TMZ Live" Friday ... and he told Charles everything Diddy does behind bars is being scrutinized, including the brawl.

Robertson says a judge will eventually look at his prison record and decide if he deserves credit for good behavior ... and this violent fight could be a serious strike against him.

Diddy's currently scheduled to get out of prison in February 2028 ... but that date assumes he earns credits for good behavior.

Robertson says prison officials will investigate and figure out if Diddy was in the wrong in this cellblock showdown ... and if so, he could be extending his stay in the federal pen.

Diddy wound up in solitary confinement after the fight ... and Robertson explains why that is a good indicator on the status of the prison probe.

We also asked Robertson if Diddy would have been better off turning the other cheek here ... but there's some specific reasons he thinks that would have been the wrong move.

Diddy's looked comfortable at Fort Dix every time we'd seen him before this ... and it sounds like there's a chance he may be extending his stay.