Where does “ἰχθυακός” come from?

ἰχθυακός (Ancient Greek) comes from Ancient Greek ἰχθύς, from Ancient Greek ἀετός, from Proto-Hellenic ayyetós, from Proto-Indo-European h₂ewyetós, from Proto-Indo-European h₂éwis — bird.

ἰχθυακός (Ancient Greek): fish-, of fish