Ga(As)Sb quantum dots (QDs) are grown on GaAs substrate in the Stranski-Krastanov mode. The molecular beam epitaxial (MBE) growth is monitored by reflectance anisotropy spectroscopy (RAS). For certain photon energies of the light used for RAS, the RAS signal values for GaAs layers, GaSb layers, and Ga(As)Sb QD surface morphologies can clearly be distinguished. The finding verifies that RAS is a valuable tool to identify growth of these QDs.