Fishy Piffle

Although the topic seems incredibly callow, fish farts have been bothering me for years. From an early age, I would observe these little bubbles rising from the rear end of our family goldfish, and wonder. Was it a fart? Or was it just some strange underwater mechanism unrelated to the digestive tract?

To my disappointment, there is a dearth of research on fish flatulence. There is no end to speculation, however, from both the scientific community and from perversely interested pet owners. The existence of fish toots is currently in debate among ichthyologists. Some believe that the digestive tracts of fish really do produce gas as a by-product of digestion; others insist that gas created in fish intestines ends up being mixed within fish feces.

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The bubbles that arise out of a fish's rear may not necessarily be a toot; researchers actually know of several gasses, not a result of digestion, but nevertheless released by fish through their anuses. For instance, the sand tiger shark will take in a superfluous amount of air when near the surface. This extra air is then released through the anus so that the shark can sink into the depths. Another fish pseudo-fart is produced by herring. Herring "farts" were discovered by Dr. Richard J. Krejsa, a professor of fisheries at Cal Poly State University. While tagging wild herring in Alaska, Krejsa observed numerous gas bubbles reseased from the tail ends of the fish. After careful dissection, Krejsa found that herring actually possess a small air bladder with a duct opening right beside the anus; the bubbles were coming from here. Herring use their "farts" as a defense mechanism: when a large school of herring is threatened, the fish simultaneously release gas from their air bladders, creating a loud and noisy gas cloud that confuses the predator and allows the school to escape. When another biologist, Dr. Harold Harvy, discovered the excretory release of swim bladder gasses by salmon, he called it "exkrejsiation" after Dr. Krejsa.

Still, the search for genuine fish farts is promising. Since goldfish have a simpler digestive tract than humans, there may be more bacteria present in the gut to feed on unabsorbed food and thus more gas produced by the bacteria. According to ichthyologists at the University of Guam, fish who consume coral are the most likely to pass gas. Though most fish types have alkaline intestinal environments, coral-eating fish have more acidic tracts to help digest the tough coral. Coral is made of calcium carbonate, and carbon dioxide is a natural product of the acid and calcium carbonate reaction. The Guam scientists conjecture that this excess CO₂ buildup results in underwater flatulence.

Unfortunately, this phenomenon has never been observed, but it could also be your claim to fame on your next scuba dive. While on the lookout for true fish flatus, also keep in mind that fish living near the ocean floor are probably unable to fart. Due to the high water pressure at such depths, any gasses released by the fish will stay in solution form and never surface as gas bubbles.