1. A son of Asopus and Metope, from whom the Boeotian river Ladon was believed to have derived its name of Ismenus. (Apollod. iii. 12. § 6.) The little brooks Dirce and Strophie, in the neighbourhood of Thebes, are therefore called daughters of Ismenus. (Callim. Hymn. in Del. 77; comp. Euirip. Bacch. 519; Diod. iv. 72.)

2. According to other traditions, Ismenus was a son of Amphion and Niobe, who when struck by the arrow of Apollo leaped into a river near Thebes, which was called Ismenus, after him. (Apollod. iii. 5. § 6; Plut. de Fluv. 2.)