AROA´NIUS(Ἀροάνιος), the name of three rivers in Arcadia.
1. Or OLBIUS (Ὄλβιος), called ANIAS(Ἀνίας) by Strabo, a river rising in the mountains to the north of Pheneus, and falling into some caverns called katavothra, near the latter city. When these caverns happened to be blocked up, the waters of the river overflowed the whole plain, and communicated with the Ladon and the Alpheius. (Strab. 8. p. 389; Paus. 8.14.3, 15.6.)
2. （ Katzána), a tributary of the Ladon, and flowing past the western side of Cleitor. (Paus. 8.19.4, 21.1.) Polybius (Plb. 4.70), without mentioning the name of the river, properly describes it as an impetuous torrent from the neighbouring mountains. The trout in the Aroanius are said to have sung like thrushes. (Paus. 8.21.2; Athen. 8. 331e.; Plin. Nat. 9.19; Leake, Morea, vol. ii. pp. 241,263, seq.) This river rose in the Aroanian mountains (ορη Ἀροάνια, Paus. 8.18.7), now called Khelmós, which is 7726 feet in height. (Leake, Peloponnesiaca, p. 203.)
3. A tributary of the Erymanthus, flowing on one side of Psophis. (Paus. 8.24.3.)