A young man stabbed in Port Phillip Prison on New Year's Day went to jail to do his time and not to die on his cell floor, friends calling for answers have said.

Hassan Jeng was stabbed to his chest inside his cell in Scarborough North, a unit for at-risk prisoners, after a fight broke out about 7pm on Monday.

Six other prisoners were inside the cell at the time.

Guards found Mr Jeng on the ground with a stab wound to his chest. The 23-year-old died in his cell.

Mr Jeng, whose criminal history included assaults and driving offences, is from Sierra Leone and was a father to four young children.

It's believed he had spoken to two of his children just half an hour before he was attacked.

"It should be a safe place," friend Godsway Atabudzi said.

"He was only in there to do his time and come out.

"We understand he committed a crime, we understand he was in jail, fine, but what happened?"

The homicide squad investigation into who was responsible and the motive behind the crime is ongoing.