423,000 (Johnstone and Mandryk 2001).
Delta state: Ukwuani, Ethiope East, Ndokwa West, Ughelli North, Ughelli South, Isoko North, and Isoko South LGAs; Bayelsa state: Sagbama LGA; Edo state: Orhionmwon LGA.
Ozoro, Ofagbe, Emede, Owe (Owhe), Elu, Aviara, Iyede, Imiv, Enhwe, Ume, Iwire (Igbide), Olomoro, Iyede-Ami, Unogboko, Itebiege, Uti, Iyowo, Ibiede, Oyede, Uzere, Irri (Iri), Ole (Oleh).
Used as L2 by Eruwa [erh].
Latin script [Latn].
“Sobo” and “Igabo” are offensive names. “Biotu”, interior people, is the Izon name for the Isoko and is not meant offensively by the Izon; however, the Isoko do not like it.