A device (1) for irradiating titanium-dioxide-coated fibers with UV radiation includes a housing (2) that is filled with water. Bodies (4), including strips (5), which consist of quartz glass, are arranged in the housing (2). LEDs (7), which emit UV radiation, are paired with at least one of the longitudinal edges of the strips (5). UV radiation is uniformly emitted to the fibers by the strips (5), so that these fibers acquire anti-fouling properties.