OMG, Fighting in Hockey is a Tradition

That's been the norm since the beginning of hockey. Once they hit the ice or whatever, the refs stop it because serious injury is likely to occur once they're down on the ice (concussions, etc.), and they want the game to keep moving.

You'll also notice that Arron Asham stops as soon as Beagle goes down. Plus, it's always consensual. Nobody ever starts throwing punches until both players drop 

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Till today, I know that fighting in Hockey is allowed and is a tradition since the beginning of this game.

If you want to know why is fighting allowed in Hockey, you can click Fighting in Ice Hockey on Wikipedia. OMG!