The gain degradation behavior of erbium-doped fiber amplifiers (EDFA) in a master oscillator power amplifier (MOPA) configuration was characterized using the fibers irradiated with varying irradiation dosages from our in-house Co60-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist for erbium-doped fibers with relatively low concentrations of the co-dopants cerium and germanium added. For fibers with relatively high concentrations of germanium and comparable levels of cerium co-dopants, highly effective radiation hard behavior is exhibited, which is attributed to germanium alone. A fiber optimized for efficiency also provides a radiation-hard EDFA where after a 100-kRad (1000 Gy) exposure, the degradation in signal gain was 5 dB at a MOPA pump power of 315 mW.