Last week, I relieved the parental duties of a close friend by spending an evening with her 6-year-old daughter, Kahea. I had forgotten how entertaining kids could be at that age, especially if they are as talkative and curious as this one. At one point in the early evening, she grabbed my hand, dragged me onto the lanai, and sat me down in front of a fish tank. She looked at me with a huge grin on her face and said with a giggle, “Molly, meet the Mollies.”
I was staring at a fresh water tank full of what looked like guppies, minnows, and apparently mollies.
“I like to sit and stare,” she said. And that is exactly what we did in silence, for maybe two seconds, before she turned to me and asked, “Do fish fart?”.
Hmm, do they? I wasn’t sure. My immediate thought was probably but not in the conventional Homo sapiens manner. Given that fish control their buoyancy through gas exchange with their swim bladder, the gas has to go somewhere, right? Well I pondered this simple question throughout the evening and once I put Kahea to bed, I immediately contacted my friend Google for some answers. Apparently, Kahea and I were not the only ones out there to have contemplated fishy flatulence for there are loads of websites dedicated to this and even a few scientific papers.
Drumroll please…..the answer is yes and no, for it actually depends on your definition of a fart. Human farts are by-products of digestion, the release of gaseous waste from intestinal bacteria through your bum. According to this definition, fish do not fart. Unlike humans, dogs, and other stinky mammals, fish consolidate their digestive gases into their poop and expel it in a gelatinous form. Thus gas is not technically expelled through their anus via the digestive tract. But, if your definition of a fart is simply boisterous sounds that transpire through the anus, well then there is actually a fish that farts.
Herring is one of the few known fish to emit high pitch sounds from their anus, producing distinctive bursts of pulses scientifically referred to as Fast Repetitive Tick (FRT) sounds…. if only they put an ‘And’ between the Fast and Repetitive. These bubbling back-end bursts form 7-65 pulses, lasting 0.6 to 7.6 seconds. It is thought to be the result of gas expulsion via the anal duct from their swim bladder. All fish must inflate and deflate their swim bladder to travel up and down in the water column, but unlike the herring, nearly all of them expel air through their mouth or gills, not their anus.
Herring are a part of the Order Clupeiformes and clupeid fish can detect sound frequencies beyond the hearing of most other fish including their predators. They have a sophisticated auditory system that is advanced in part due to a gas-filled sac near the inner ear that acts to amplify sound pressure. It is hypothesized that these little whizzpoppers are breaking wind specifically to communicate with each other for the noise seems to be triggered by darkness and with high fish densities. Through their high frequency farts, they can maintain contact with each other at night without revealing their location to predatory fish. Oh the magical work of evolution.
Check out this video of farting fish: https://www.youtube.com/watch?v=OcwCYIfm6eA