How could a fish have gotten into a percolator?

In an episode of the classic cult TV show Twin Peaks; Sheriff Truman and Agent Cooper are warned by Pete Martell not to drink their coffee because a fish has found its way into the percolator, thereby contaminating their drinks. My question is; how could the fish have wound up in the percolator without someone placing it there? Perhaps Pete's wife put it in there because she was mad at him? Thoughts?