Bethioua (Arabic: بطيوة), formerly Arsenaria, Portus Magnus, Arzew (أرزيو, ʾArzyu), Vieil Arzew ("Old Arzew"), and Saint Leu, is a port town and district near Arzew in Oran Province in northwestern Algeria. It has a gas port, petrochemical facilities and desalination plant.

Bethioua is located on the ruins of the ancient Roman settlement of Arsenaria or Portus Magnus.

The region itself belonged to the Battiwa (Ibeṭṭiwen), a group of Berber clans which arrived from the Rif mountains, mainly Ait Said and Temsaman tribe. They were composed of clans from Zegzawa (Izegzawen), the Ait Mait and their Maraboutic leader Sidi Amar Ben Ahmed whose mausoleum lies facing the sea.^[1] Originally settled in Mazagran near the city of Mostaganem, the Ibeṭṭiwen and Battiwa the bey of Mascara gave them coastal territory a little further west^{[clarification needed]} in 1784. Under French occupation, the Battiwa took refuge in Mazagran again.^{[clarification needed]} Most of them were given back their land by the authorities.^{[who?][clarification needed][when?][2]} Today only elders can still really speak the tribe language.^{[clarification needed][3]}

When the Anglo-Americans invaded Algeria in November 1941 (Operation Torch), the American troops who captured Oran landed at Beach Z,^[4] which was the strip of coastline between Arzew and Bethioua.^[5]

v t e Oran Province
Oran District	Oran
Aïn El Turk District	Aïn El Turk Mers El Kébir Bousfer El Ançor
Arzew District	Arzew Sidi Ben Yebka
Bethioua District	Bethioua Mers El Hadjadj Aïn Bya
Es Sénia District	Es Sénia El Kerma Sidi Chami
Bir El Djir District	Bir El Djir Hassi Bounif Hassi Ben Okba
Boutlélis District	Boutlélis Aïn El Kerma Misserghin
Oued Tlélat District	Oued Tlélat El Braya Boufatis Tafraoui
Gdyel District	Gdyel Hassi Mefsoukh Ben Freha

35°48′N 0°16′W / 35.800°N 0.267°W / 35.800; -0.267

• Metzmacher, M. (1979 a). Les oiseaux de la Macta et de sa région (Algérie) : Non passereaux. Aves, 3-4 : 89–123.