1. A son of Poseidon and the nymph Olbia, from whom the town of Astacus in Bithynia, which was afterwards called Nicomedeia, derived its name. (Arrian. ap. Steph. Byz. s. v.; Paus. v. 12. § 5; Strab. xii. p. 563.)

2. The father of Ismarus, Leades, Asphodicus, and Melanippus, whence Ovid calls the last of these heroes Astacides. (Apollod. iii. 6. § 8 ; Ovid Ibis. 515.)