An extremely simple setup for real-time color digital holography using single-mode fibers as light guides and a directional coupler as a beam-splitting device is presented. With the directional coupler we have two object beams and one residual crosstalk used as a reference beam. This facilitates the adjustment and improves robustness. With the use of graphics processing units, real-time hologram reconstruction was possible. Due to adaptation of the optical setup and scaling, zero-order and complex image influence is highly reduced.