Fighting in the NHL really is just part of the game. Watch as Matt Martin knocks out Tom Kostopoulos and then quickly calls from the training/medical staff to come onto the ice and attend to Kostopoulos.
Kostopoulos, of the New Jersey Devils, starts the fight after Martin, of the New York Islanders, body-checked his team-mate. It's clear that both players are happy enough to be involved with the fight and soon as Martin knocks out Kostopoulos, the hostilities are ended. Even the commentators speak openly about Martin's prowess as a fighter in the NHL.
The Islanders and Martin would go on to win the game 3-1 and remain in the hunt for a place in the NHL play-offs.