You mean, where there's a fish, there could be a Penguin.
4 seconds sound clip from the Batman (1966) movie soundboard.
You can hear this line at 00:13:05 in the Blu-ray version of the movie.
Quote context
[...]
- Loose to plague us with his criminal conundrums.
- Could be any one of them, but which one? What... Which ones?
- Pretty fishy what happened to me on that ladder.
- You mean, where there's a fish, there could be a Penguin.
- But wait. It happened at sea.
- Yet, an exploding shark... was pulling my leg. The Joker.
- It all adds up to a sinister riddle.
[...]