He married into the Wander family (Hercules Chemical was founded by Samuel Wander) in the late 1940s and joined the company in 1946, working at its office and factory in lower Manhattan, New York City. This was after he had served as a second lieutenant in the U.S. Army during World War II.
He became national sales manager at Hercules Chemical in 1956 and was appointed its president in 1962. In 1998, following the sale of the company to its employees under an ESOP, Fidler was named chairman, David M. Siegal took over as president and Len Ruvolo was named vice president/CFO.