Single-crystal rods and fibers of Bi12GeO20 (BGO) of various sizes were successfully grown from a rod of mixed Bi2O3 and GeO2 by the improved floating zone device. The grown stoichiometric EGO crystal has a lattice constant of 10.14388 +/- 0.00001 Angstrom, a uniform composition along the axial position. For a nonstoichiometric crystal, its lattice constant decreases and its transmittance increase with the concentration of GeO2 up to the stoichiometry.