Halifax police said Monday evening they had a man in custody in connection with the Saturday morning death of James Philip Mattatall, 23, of Dartmouth.
The man turned himself in. Police said no decision has been made on whether or not to lay charges.
Police also said they are still looking for witnesses and that anyone with information should contact police or Crime Stoppers Canada.
A fight broke out inside a downtown bar and spilled onto Argyle early Saturday morning. Mattatall was struck to the ground just before 3 a.m.
"The suspect struck James and fled south on foot," said Const. Brian Palmeter of Halifax Regional Police.
Police said there are indications Mattatall may have been trying to break up the fight.
On Monday Mattatall's friends and family held a gathering at his house.
"He was there for all of us when anybody needed it … he never thought about himself," said Justin Dobson, a close friend.
"He did absolutely nothing to deserve this. Maybe the person who did this didn't mean to do this at all," he said.
"But I know that there was a lot of people there and somebody has to know something."
Daniel Mattatall, James' older brother, urged witnesses to speak out.
"For my mum's, my parents' sake, if you know anything just come forward," he said.
"I just can't describe it; I hope no one has to go through this, ever. Just the worst feeling ever ... He was my baby brother and I loved him a lot and I miss him."
Dobson remembered Mattatall as someone to look up to.
"He was a coach, he was a mentor to kids; he was a person that we should all model ourselves after," he said.
"I just hope he knows that we all love him."
In the wake of Mattatall's death, Joe McGuinness, owner of Durty Nelly's, said a program to prevent troublemakers from accessing bars is in the works.
"We would share information among bar owners on individuals who have been barred from their premises for any number of reasons over intoxication, damage, violence," he said.
"Collectively, all of us would agree to restrict access to liquor establishments to those individuals."
McGuinness said bar owners expect the new program to be in place by early 2012.