A lighting fixture and method resist bio-fouling of a window of the lighting fixture when submerged and exposed to biological organisms within a surrounding environment. Ultraviolet radiation is directed to the window from a source within the fixture, enabling transmission of the ultraviolet radiation through the window to an outer surface of the window to combat biological organisms to which the outer surface of the window is exposed when submerged, and allowing light from a source behind the window to be projected effectively through the window and into the surrounding environment.