Fisher, Alfredsson and Schaefer, put together in this pre-season to give the Senators' second line some scoring punch, contributed a couple of goals to Ottawa's cause before a crowd of 18,081 at Scotiabank Place.
One night after they combined for three of the Senators' five goals in a win over Toronto, Fisher had a goal and an assist, Schaefer had a goal and Alfredsson recorded three assists.
Chris Neil also scored for Ottawa (5-3-0) and Martin Gerber went the distance in the Senators' net, making 31 saves.
Alex Kovalev and Tomas Plekanec replied for Montreal (2-5-0).
David Aebischer played the entire game in the Canadiens' goal and stopped 19 shots, while prospects Guillaume Latendresse and Andrei Kostsitsyn, expected to be battling for the same roster spot, each helped their cause with an assist.
The teams played Monday night at Truro, N.S., and Montreal won that game 7-3.
On Thursday, Aebischer's first real action of the night was to scoop the puck out of his net when Schaefer scored on the Senators' first chance of the game following a pass from Fisher almost nine minutes in.
Kovalev tied it for the Canadiens before Fisher made it 2-1 on the power play.
Meszaros notched his first goal before the end of the period and scored again on the power play early in the second to make it 4-1.
Plekanec and Neil then traded rebound goals and Ottawa led 5-2 after two periods.
The Senators finished 2-for-5 with the man advantage. The Canadiens went 0-for-6.
The teams meet again Saturday night at Montreal's Bell Centre to conclude their pre-season schedules.