A fiber plug facilitates optical coupling of a light-guiding fiber to a plug receptacle and includes a plug housing for receiving and locking parts of the fiber plug in position relative to one another. The plug housing has: a fiber inlet and a fiber bearing for the spatially fixed reception of the fiber; optically downstream of the fiber bearing along a beam path, an optical lens for collecting light exiting at an end face of the light-guiding fiber and for collimating the collected light; and a coupling surface with an output of the beam path and with a coupling structure for connection to a receptacle structure that is complementary to the coupling structure. An adjustable optical element is arranged optically downstream of the fiber bearing in the beam path and has a first component of a magnetic coupling consisting of two components and a first component of a kinematic coupling.