A novel table-top experiment is introduced to detect photon-axion conversion: WISP searches on a fiber interferometer (WISPFI). The setup consists of a Mach-Zehnder-type interferometer with a fiber placed inside an external magnetic field, where mixing occurs which is detected by measuring changes in amplitude. Hollow-core photonic crystal fibers (HC-PCF) will be used to achieve resonant mixing that is tuneable by regulating the gas pressure in the fiber. An unexplored axion mass-range (28 meV–100 meV) can be probed reaching the two-photon coupling expected for the QCD axion.