As rivers are generally fertile, Inachus had many children, the chief of whom were his two sons, Phoroneus and Aegialeus or Phegeus, and his two daughters, Io and Philodice, wife of Leucippus.
Io, daughter of Inachus, the first king of Argos, is seduced by Jupiter (Zeus in Greek), who hides behind the dunes to avoid hurting the jealous Juno (Hera in Greek).