A punch-up during the Montreal Canadiens' home-opener last night reopened a discussion around violence in hockey after the Canadien George Parros was knocked unconscious during a fight with Leafs enforcer Colton Orr late in the third period.

Parros slammed face first into the ice after a misplaced punch sent the forward sprawling over Orr’s body. He fell hard on his chin and lay motionless for several minutes while a muted crowd looked on.

Parros was taken off the ice on a stretcher.

A tweet from the Canadiens’ Twitter account Wednesday announced Parros had been released from hospital, suffered a concussion and would be out “indefinitely.”

It’s a situation all too familiar for ex-NHL enforcer Jim Thomson, who said he "lived in fear" before hockey games.

Thomson, who protected Wayne Gretzky on the L.A. Kings in the '90s, says he was the George Parros of his era.

“Hockey should be like other sports. If you fight, you’re out of the game,” Thomson said in an interview with Carol MacNeil, host of CBC News Now Wednesday.

Thomson describes being so rattled by what was expected of him as a hockey fighter he turned to drinking and drugs to help him get through pre-game jitters.

Retired from hockey, Thomson has spent years recommending a blanket ban on fighting in the sport and cites falling registration numbers at the youth level as evidence violence is bad for the game.

A fight in last night’s home-opener in Montreal reopened a discussion around violence in hockey after the Canadiens’ George Parros was knocked unconscious as a result of a fight with Leafs enforcer Colton Orr late in the third period. ( Jean-Yves Ahern/USA TODAY/Reuters)

“Take the violence out at the top and we’ll see it filter out of minor hockey,” Thomson said.

“When I see George hit the ice with his head, I’m afraid of another death,” he said, referring to an on-ice fight which led to the death of 21-year-old senior hockey league player Don Sanderson in 2009.

In an interview with the CBC's Peter Mansbridge Monday that touched on the league's new helmet rule and violence in hockey, NHL commissioner Gary Bettman said fighting was "part of the fabric" of hockey.

But, Bettman added change is coming, albeit gradually.

"When we make changes, we respect the tradition" of the game. "You don’t throw a light switch to effectuate change. The game is evolving and we are constantly wrestling with that balance,” Bettman said.

“It's the name of the game. If you fight, you get hurt. I got KO’d plenty of times and look how good I am,” Don Cherry said on Hockey Night in Canada Monday following Parros's injury.

The NHL’s new, so-called keep-your-helmet-on rule comes in to effect this season and requires players to keep their helmets on during a fight. If they don't comply, players are subjected to an extra two-minute minor penalty for unsportsmanlike conduct. The rule was made strictly with player safety in mind to reduce the risk of a player hitting his head on the ice while not wearing a helmet.

Parros had his helmet on when he suffered a concussion after fighting with Orr. It was their second fight during the game.