He played for Choate Rosemary Hall in 1973-74 and then for the University of New Hampshire from 1974 to 1978. Undrafted by the NHL, Fontas turned pro with the Saginaw Gears in 1978-79 and scored 81 points and was the top American rookie in the International Hockey League.
The Minnesota North Stars were sufficiently impressed to sign him as a free agent in 1979. He played one game in each of the next two seasons for the Stars while playing most of the time in the minor pros.
Fontas retired in 1985.