A native of Limoges, he studied biology at the Sorbonne and in the laboratory at Saint-Vaast-la-Hougue.
For the next fourteen years he served as a naturalist at the Laboratoire de biologie marine in Banyuls-sur-Mer.
From 1920 he worked in the zoology department at the Muséum national d'histoire naturelle in Paris, where in 1938 he succeeded Charles Joseph Gravier (1865–1937) as professor and director of the department of zoology (worms and crustaceans).
Fage made contributions in the fields of carcinology (study of crustaceans), arachnology and speleology.
With Édouard Chevreux (1846–1931) he co-authored the section on "Amphipodes" for the Faune de France (1924).