The police have arrested another 25-year-old man on suspicion of grave and criminal assault following the fight which took place in the area of Hope Street and Bond Street, around 22:45 on 15 December.
He has since been released on police bail.
Police issued a witness appeal on 18 December urging people to come forward with information about the fight. They believe the two men may have been involved in a further altercation in the area of Wharf Street and Conway Street.
Anyone with information is asked to contact police on 612612 or anonymously via Crimestoppers on 0800 555 111.