The interactions of carbon with the probe nucleus 111In have been studied in germanium using the perturbed angular correlation method, which has the ability to detect the microscopic environments of the probe atom by means of the interaction of the nuclear moments of the probe with the surrounding electromagnetic fields. At high dose carbon implantation in germanium two complexes have been identified by their unique quadrupole interaction frequencies. An interaction frequency of νQ1 = 207(1) MHz (η = 0.16(3)) appeared at annealing temperatures below 650°C. Above 650°C, it was replaced by a second interaction frequency of νQ2 = 500(1) MHz (η = 0). The frequencies are attributed to two different carbon indium pairs. The orientation of the corresponding electric field gradients and the thermal stability of the defect complexes are studied.