Cetus

Cetus, the Denizen of the Land of Light and Rain. Not much is known about her except that it has eaten every living thing in the ocean and subsequently taken a nap. It is likely aquatic. Curiously, the meteor carrying baby Rose also killed all aquatic life in a nearby lake.

In Greek myth, a Cetus was a large fish, serpent, whale, or sea monster, which would explain all of the fish being eaten.