He qualified for the men's 100 m freestyle, by receiving a Universality place from FINA in an entry time of 1:09.84.
He challenged six other swimmers in heat one, including 34-year-old Mumtaz Ahmed of Pakistan.
He rounded out the field to last place in a lifetime best of 1:09.40, exactly 43 seconds faster than a historic record time of 1:52.72, held by Equatorial Guinea's Eric Moussambani in 2000.
Nziyunvira failed to advance into the semifinals, as he placed sixty-ninth overall out of 71 swimmers in the preliminaries.