Roman Catholic Diocese of Mahagi–Nioka Tags: Clerical Administrative Region, Diocese.The Roman Catholic Diocese of Mahagi–Nioka (Latin: Mahagien(sis) – Niokaën(sis)) is a diocese located in the city of Mahagi–Nioka in the Ecclesiastical province of Kisangani in the Democratic Republic of the Congo. area (km2) 1.849e+10 country Democratic Republic of the Congo jurisdiction Diocese Learn more... Loading...