Do they know they're about to become food?

I was in Fredericton New Brunswick this week, doin' the road thing for work. Yesterday, we were in a fish 'n chip place and I'm taking in my surroundings. Beside me, there's a huge fountain / pool thingy, filled with fish. The fish are (it seems to us) staring up out of the water at us. Out of nowhere, I say, "I wonder if the fish freak out when they smell vinegar?"