Take another look at the sentence:
Hungry for dinner, the surface is where Gert the goldfish waited in anticipation
of food flakes.
Hungry for dinner, a phrase, is describing surface when its target should be Gert. When a modifier is next to a word it doesn't logically describe, it is misplaced.
To fix the problem, you should organize the sentence like this: Hungry for dinner, Gert the goldfish waited at the surface in anticipation of food flakes.