Prior to joining the University of Western Sydney in 2009, he was a lecturer at the University of Tasmania. Before then he was a research fellow at Monash University following the completion of his PhD at the same university. Fidelis has worked as a site engineer on dam projects in Zimbabwe and as a consulting engineer in Chile and Australia. He is currently a member of the Australian Standard Committees on Steel Structures, BD-001, Cold-Formed Steel Structures, BD-082 and Security Screen Doors and Window Grilles, CS-023. Fidelis is a member of The Institution of Engineers, Australia (IEAust), the Welding Technology Institute (WTIA) and the Australian Steel Institute (ASI).