Fiske left home and traveled to Sacramento in 1858, where he worked as a banker, a clerk, a farmer (in San Jose) and finally as an assistant photographer, first to Carleton Watkins at his Yo-Semite Gallery (1868), then to Thomas Houseworth, both of San Francisco. In 1874 he returned to work for Watkins, who had changed his business name to Yosemite Art Gallery. In 1875 Fiske went with Watkins to Yosemite Valley, photographing there through the summer and fall. When Watkins lost his gallery, Fiske went into partnership with Charles Staples, running a boardinghouse (1876-77). From the time of its dissolution he remained in the photographic trade, working in Marin and Santa Clara counties. He probably traveled through Sequoia Valley with Eadweard Muybridge in 1872, and for many years was close friends with Yosemite's caretaker, the conservationist Galen Clark. In 1879 he moved to Yosemite Valley, where he resided for nearly forty years, all year round.
Fiske produced images of California's elegant seaside resorts, crumbling Franciscan missions and, predating Edward Weston by forty years, the pounding surf off Point Lobos. He was seen winters, his equipment loaded onto a sled, and summers, pushing his "cloud-chasing chariot," a wheelbarrow, loaded down with his 11x14 plate camera.