Etymology

From the Ancient Greek ἰχθυοφάγος ‎(ikhthuophágos, “fish-eating”; and substantivised as a plurale tantum proper noun: “the Fish-eaters”, “the Ichthyophagi”); reinforced in the general sense (“that which consumes fish”) by the English ichthyo- ‎(“fish”) +‎ -phage ‎(“eater”).