Fifty-nine-year-old Stanford suffered a broken nose, two black eyes and mild concussion in the fight at the Joe Corley Detention Facility in Conroe, Texas.
He spent the weekend in hospital before being returned to his jail cell on Monday.
Mr Stanford had previously been taken to hospital in August 2009 for five days following heart problems.
The former chairman of the Stanford Financial Group, who saw his assets frozen following his arrest in February 2009, will stand trial on 21 separate criminal charges relating to a Ponzi scheme he is alleged to have run from his offshore bank in Antigua.
Mr Stanford is accused of targeting several sportsmen in the fraud, including baseball players Johnny Damon and J. D. Drew.
According to prosecutors, Mr Stanford used the proceeds to pay for an extravagant lifestyle of Caribbean homes and private jets.
By Claire Archer