The propagation of a surface plasmon-polariton (SPP) wave can be guided by the interface of a metal and a columnar thin film (CTF). Theory predicts that the angle of incidence on the prism/metal interface in the Turbadar-Kretschmann- Raether prism-coupled configuration required to excite the SPP wave shifts upon infiltration of the CTF by a fluid. Otherwise identical CTFs of different thicknesses were partnered with dense thin films of aluminum in optical experiments. Regardless of the angle between the morphologically significant plane of the CTF and the cross-sectional plane of the prism, the angle of incidence for exciting the SPP wave was found to shift to a higher value when the CTF was infiltrated by a fluid of refractive index in excess of unity. Experimental data indicated that the angle between the morphologically significant plane of the CTF and the cross-sectional plane of the prism should not exceed about 45° for high sensitivity.