[en] Radiation detectors based on multiple single crystalline scintillating fibers are promising for next generation of heterogeneous electromagnetic calorimeters to be exploited in high-luminosity colliders for high-energy physics experiments. These novel fiber-based detectors consist of long single crystalline rods placed in heavy metal absorber, thus, the light propagation conditions in these fiber-like structures are of crucial importance for obtaining uniform response to electromagnetic shower. In this work, the uniformity of Czochralski-grown cerium-doped gadolinium aluminum gallium garnet fibers was studied by employing confocal optical microscopy. Growth related defects were observed on a micrometer scale. Light attenuation length was estimated and found to vary in nominally identical fibers. The influence of crystal growth defects and surface polishing quality on light propagation is discussed.