The young south Dublin men were released from custody last night after being detained for most of yesterday at Pearse Street Garda Station.
A 21-year-old man from Maynooth, Co Kildare, received serious head injuries after a row broke out at 3.20am at Essex Street on December 8.
It was initially feared that the victim, a student, would die, but his condition improved after extensive treatment at Beaumont Hospital.
The young man was released from hospital over Christmas and is said to be making "a very slow recovery".
Sources say that the Maynooth man had been socialising in Dublin with two friends on the night of the assault.
The three friends came across a group of six men in the Essex Street area and a 'slagging match' ensued, say sources.
"This quickly descended into violence, a fight occurred and the victim suffered a very bad assault," a source explained.
The attack was investigated by detectives from Pearse Street Garda Station and yesterday morning officers made five arrests and also detained another suspect for the purpose of interviewing him.
This individual is a 17-year-old boy who had never come to garda attention before.
The six young men are aged between 17 and 20 and have addresses in the Ringsend and the Dublin 2 area.
Sources say analysis of CCTV footage helped to identify some of the arrested men.
A file will now be prepared for the DPP.
"It is very likely that there will be charges down the line; this was a particularly horrific assault that could have easily resulted in death," said a senior source.
The six young men are all also understood to have been socialising before the attack.
The victim of the assault was rushed to St James's Hospital, but was later transferred to Beaumont because of the extent of his head injuries.
According to the latest figures from the Central Statistics Office, nationwide assault figures fell by 9.5pc last year up to September compared to the same period in 2010.