http://www.newscientist.com/article/dn4343-fish-farting-may-not-just-be-hot-air.html
New Scientist
Fish farting may not just be hot air
00:01 05 November 2003 by Celeste Biever
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Biologists have linked a mysterious, underwater farting sound to bubbles coming out of a herring’s anus. No fish had been known to emit sound from its anus nor to be capable of producing such a high-pitched noise.
“It sounds just like a high-pitched raspberry,” says Ben Wilson of the University of British Columbia in Vancouver, Canada. Wilson and his colleagues cannot be sure why herring make this sound, but initial research suggests that it might explain the puzzle of how shoals keep together after dark.
“Surprising and interesting” is how aquatic acoustic specialist Dennis Higgs, of the University of Windsor in Ontario, describes the discovery. It is the first case of a fish potentially using high frequency for communication, he believes.
Arthur Popper, an aquatic bio-acoustic specialist at the University of Maryland, US, is also intrigued. “I’d not have thought of it, but fish do very strange and diverse things,” he says
The difference is the fish doesn't need a teleprompter.