ichthyophage

ichthyophage means that which consumes fish; any fish-eating thing or (more rarely) person.

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”).

noun

That which consumes fish; any fish-eating thing or (more rarely) person.
Anglicisation of Ichthyophagi

Definitions & examples from Wiktionary (CC BY-SA 3.0).