Aaron Hernandez -- Will Stay in Solitary Confinement ... 'It's In His Best Interest'

Aaron Hernandez will NOT be moved out of solitary confinement at the Bristol County Jail ... after officials decided it would be in his "best interest" to remain isolated from the general population, TMZ has learned.

As we previously reported, the alleged murderer was placed in solitary right after he was booked -- fearing violent inmates might view the former NFL star as a "prize." But officials vowed to review Aaron's situation and would consider moving him if they felt it was safe.

But officials met yesterday and a rep for the jail tells TMZ ... after serious discussion, they decided NOT to move Hernandez, believing it would be in his "best interest" to stay. The insinuation -- he's still in danger.

The jail rep says the ex-NFL star is "doing well" behind bars ... and hasn't had any problems so far.