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Excitation functions were measured for complex fragments with atomic number Z = 5-20 emitted from the compound nuclei 70 • 76 Se produced in the reactions 58 • 64 Ni + 12 C. Mass asymmetric fission barriers were extracted by fitting the excitation functions with a transition state formalism. The extracted barriers were compared with those calculated from macroscopic nuclear models. The measured barriers for symmetric fission seem to support the hypothesis of a shape-dependent congruence energy, which doubles for fission of strongly indented saddle-point shapes. All of the measured excitation functions can be scaled onto a single straight line according to. the transition state prediction.