After finishing his musical studies in Oslo, Stockholm, Vienna and Copenhagen, Fiskum was employed as violinist by Oslo Filharmoniske Orkester in 1960.

He established Det Norske Kammerorkester in 1977, and later became concertmaster for Trondheim Symphony Orchestra (1977–84).

He was employed as Professor at Department of Music at the Trondheim Musikkonservatorium (1983–).

Fiskum was also a teacher at the Heimdal Upper Secondary School for a while, and played within Hindarkvartetten and Trondheim Trio.

[2][3] He founded the Trondheim Soloists in 1988, and was artistic director for them until 2001.