At the 1996 Summer Olympics in Atlanta Fiz came fourth in the marathon.

A year later he won a silver medal at the 1997 World Championships in Athletics in Athens, finishing behind his countryman Abel Anton.

He competed in three consecutive Summer Olympics for his native country, starting in 1992.

At the 2000 Summer Olympics in Sydney Fiz came sixth in the marathon.

Fiz has continued running into masters age divisions, setting the world M55 record in the road 10K at 31:36 on January 13, 2019 in Valencia.