http://www.straightdope.com/columns/001110.html
I’ve kept 1 to 3 aquariums in my home for about 20 years (mostly freshwater). I can say that I’ve never observed a bubble from the rear end of any fish. But, on occasion, while cleaning the tank I have noticed a bubble contained in the fishy feces. Can any other aquarists confirm this phishy phenomenon? Usually, the bubble isn’t large enough to create a “floatie” but once and awhile it happens.
Uhhh…well, I don’t know much about aquariums, “floaties”(?), and such, but I do have it on pretty good authority that fish fart – on the authority of the Swedish military-industrial complex, no less. Therein lies one of the most absurd tales I’ve ever encountered, I feel I simply must share it with the world at large. You see (and I know you’re not going to believe this), it all has to do with Russian submarines. And as you will discover, Cecil is wrong – actually a great deal of research has been conducted concerning the phenomena of fish farts.
During the cold war and all through the 1980s and 90s Sweden has had this hang-up about Russia subs “allegedly” encroaching on their territorial waters. They keep hearing submarines with their underwater sonar stations, and accusing the Russians of violating their territorial boundaries. But old Ivan just plays innocent, like (except for that one time when a Russian sub accidentally ran aground on the Swedish coast, but that was just a “isolated mistake” according to Moscow. Sure.) Anyway, since no one will 'fess up about driving their subs into Stockholm’s harbour and such, the Swedes have been left guessing – and, I mean, maybe there isn’t anything out there, really, anyway.
So on occasion, somebody here comes up with an alternative explanation for the strange sonar phenomenon. For a while they suspected that they were confusing submarine noises with – dig this – the noise minks chirping. Never mind what the hell a mink is doing out in the middle of the ocean. I told you you weren’t going to beleive me, but you tell me, who could possibly make up something like this?
You are no doubt wondering by this point about the fish farting bit, and it’s so mind-boggling I still have trouble believing it myself, but, here goes: the latest theory is that these strange sonar patterns are caused by fish farts. I kid you not. The idea is that large schools of mackerel swim about and fart simultaneously, sending up a cascade of bubbles that looks on sonar like a Russian sub. To test this theory, Swedish military researchers took mackerel, filled their stomachs with gas, and squeezed them, measuring the subsequent gaseous expulsion out the backside. This provided them with a kind of average volume for your typical fish fart, which, when multiplied by the average number of fish in a school provided, a voíla, an estimate of the amount of gas let off by a school of wily mackerel in their dastardly attempts to misslead the brave (if admittedly somewhat gullible) Swedish navy.
So the answer to the original question, if one has any faith is the Swedish navy, is a resounding YES!! FISH DO FART!! Not only that, but the little bastards must be farting away like no tomorrow, because they do it so much that it looks like a bloody submarine on sonar !!
By the way, I just want to take a moment here to tip my hat in admiration for the Swedish anchorwoman who reported this story on the news without so much as cracking a smile, because by the time the story was over I was rolling the floor laughing so hard I was crying.
The wonders of science never cease to amaze, and believe me, living abroad can be such an enriching experience, sometimes.
A few years ago, I was admiring the moray eel at the Shedd Aquarium in Chicago. (I must say that for being so far from the ocean, the Shedd is quite an aquarium.) The belly of the eel was up against the glass, giving a completely unobstructed view of its anus. The eel took that opportunity and proceeded to poop. In between chunks there were several bubbles.
Yes, fish do fart.
Welcome aboard, Svinlesha! Thank you for your informative comments.
However, I would not be so quick to say “Cecil is wrong”.
If you notice, the Straight Dope column says
«However, the sand tiger shark, Carcharias taurus, gulps air into its stomach at the surface, then discharges it out the back door to attain the desired depth. Surely this qualifies as flatulence in the common sense of the term.
But purists may object that this isn’t true farting–that is, a by-product of digestion.»
The examples you are citing don’t sound like air being expelledd as a by-product of digestion, so therefore would not be true farting.
Also Cecil says “much research remains to be done”, which is probably true if one is interested in that subject.
My personal experience: I have a small aquarium at home and have never noticed any bubbles being expelled from a fish anus. Of course, many of the fish are small and so it would probably be hard to detect.
I am not a chemist, but I am a freshwater plant tank buff. One of the first things that hobbyists quickly learn is oxygen saturation. When the plants are photosynthesizing, they use they use carbon and emit oxygen. But it’s only when the oxygen levels in the water have reached the saturation point do visible O2 bubbles actually start to appear in the water. If photosynthesis is very high, the bubbles will literally stream off the plants and build up under the the leaves (called pearling).
My point is this: If methane gas can dissolve in water the way that oxygen does, would it not be logical that all the farting is not visible because the water has not reached maximum methane saturation? Small animals such as coral polyps would produce dissolved methane or very tiny bubbles that would likely dissolve immediately (IF methane dissolves – a big if). Ditto small fish.
In addition, if there is no buildup of gas, then even larger fish would emit only dissolved methane or very small bubbles that might instantly dissolve as well. Cecil did not comment on whether a fart consists of a big rip or a steady stream. That factor would depend, I would think, on the stucture of the digestive tract.
I now defer to the scientists.
Annie
So, we go from ‘do fish fart’ to farts the size of a submarine. I wonder if there’s any “trolling” going on here.
I dunnuo, (this is striclty FOAF credible, here on out), I once had a business aquaintence who did a stint as a sonar man on a USN submarine. Among the several stories of practical jokes on subs, he told a few stories about the sound of shrimp (like bacon frying), the sound of whales mating, and so on. Never once, even after the third round of beers, did he say any school of fish farted and made him think it was another sub.
Arnold – Thanks !! Only my second or third greeting since I started posting.
Lookit though – if it’s a bubble and it’s comin’ out yer backside, it’s a fart to me. I’m not really interested in hair-splitting here, however, and if you or Cece wants to call it something else, that’s fine by me.
My observation about Cecil being wrong, however, didn’t pertain to the specific topic in question. I’d like to point out that the mackerel used in this particular set of studies were no longer among the living, so actually, the test only measured the volume of dead mackerel farts (or “gas expulsions”, if you prefer). Pretty surreal, don’t you think? I readily admit that the reporter didn’t use the phrase “fish fart” either, but I leave it up to you to decide if this was for reasons of scientific accuracy or mostly due to a sense of decorum.
On the other hand, a casual perusal of Cece’s answer might misslead an unsuspecting reader to conclude that there hasn’t been much research done on this topic, and that’s what I meant about Cecil being “wrong”. There has been. I put it down to him not having time to keep up in his readings of all those top-secret Swedish military reports. I’d be really suprised if any of these findings were published in English.
Kelly – “trolling”. Cute. Can’t say I don’t blame you for not believing me, though. I hardly believed it myself.
anyi – fish fart saturation levels? You’re kidding, right?
BigDaddy – thanks for sharing. Yuck.
Well, when you phrase it that way, of course it sounds silly. Then again, the whole thread is not exactly serious. And no, I wasn’t kidding. If methane does indeed dissolve in water, then I think my theory is valid.
Annie
These are quoted excerpts from emails from my brother who works for fisheries and wildlife in MO. He’s a fairly well known researcher, mostly toxins research recently. I’m going to post twice because he sent me two separate emails and they are very different. This first one is a bit long.
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I have thought of this topic before. Because I have a special interest in gas bladder inflation (my research as a graduate student and my first publications were on this topic) I have examined many thousands of larval fish (which are translucent in their entirety) with an attention to bubbles within the digestive tract. I have never seen one solitary bubble. Bubbles are very visible under a microscope because of light refraction. I discovered that striped bass need to “prime the pump” by gulping air at the surface and injecting the ingested air into the gas bladder before the rete mirabile (the organ that takes oxygen from the blood and makes it into free gas to inflate the gas bladder. Most fish are phystoclistic, meaning they have no connection between the gut and the gas bladder, but many are physostomous, meaning that there is a connection. Striped bass are physostomous as larvae but lose the connection after the gulping takes place. If they cannot gulp air, the connection is lost and the gas bladder never inflates, resulting in a fish with a much decreased efficiency (although they can survive to moderate size). This is important in terms of fish culture. Because oil from food or unhatched eggs or dead larvae can coat the surface or increase the surface tension to the point where these tiny fish cannot break through, many cultured fish (nearly 100% in many batches) were being raised with uninflated gas bladders. This results in extreme loss of growth and increased food costs, and in fish of questionable viability if they are to be released to the wild.
Some people had hypothesized that gas production by food degradation might be substituted for access to the atmosphere, but it seems very unlikely. As I mentioned, I have never seen an actual bubble produced by this mechanism. Among thousands of fish at my lab that I kept from air ccess (not as easy as it sounds if you want to be certain) only one fish ever inflated its gas bladder, and I don’t really know how that happened - perhaps it inhaled a bubble (which were supposed to be excluded and not allowed to form by my design) or perhaps the fart mechanism came into play. Bouyancy control being of rather primary importance among fish, and most important in fish of very small size and limited mobility, production of intestinal gas would produce severe problems if it were allowed to occur.
End Quote----
Here’s his second email. He’s a natural doper don’t you think?
Begin Quote------
The gas bladder of physoclistic fish contains almost pure oxygen. This is the gas most efficiently transported by the blood, so it makes sense that the rete would use this gas to fill the bladder. There is a legend that an early fish scientist ( I have heard this recounted with more than one researcher named as the unlucky individual) was trying to determine the makeup of the at that time undetermined gas. He brought a very large and freshly dead specimen (an Atlantic Cod is the species I heard) into the lab, inserted a tube through the body wall, and lit a match, resulting in the violent explosion of the fish and some damage to himself and the laboratory. Don’t know if it is true or not, but it could be, and I think it is an amusing story.
Can such a legend truly be termed an Urban Legend if it circulates within a select group of individuals? Even if many of them are decidedly non-urban?
End Quote------
Yes, VileOrb, your brother is chock-full of interesting knowledge, but if he’s at a cocktail party trying to impress a young woman, when asked “do fish fart?”, I think a simple “no” will suffice. 
I don’t know about other fish, but Weather Loaches, also known as Dojo Loaches, frequently expel bubbles from their anuses. They most frequently do this when the weather changes, so it is undoubtedly a way to equalize pressure in their swim bladders.
In humans, whether the gas results from swallowing air or from the digestive process, it is still refered to as farting. Why wouldn’t this be so in fish?
Does the mental image of someone inflating mackerel and then squeezing them to make them toot make anyone else laugh? I mean, picture this vaudeville act:
“Melvin and his Melodious Mackerels!! Each fish produces its own distinct musical note, and when they are squeezed in the right sequence, the mackerels will play ‘Smoke Gets In Your Eyes’! You have to hear it to believe it!”
My (late) weather loach used to fart all the time!
Okay. It does depend on your definition of a fart, I guess.
But (ha ha) corys (small catfish) regularly make a mad dash to the surface for air, and after they get all of the ‘good stuff’ from the air they snatched, they let the rest out of their booty-holes. You can see it. You can see a cory at this page.
http://home.HiWAAY.net/~keiper/corys.htm
And goldfish sometimes have bubbles in their poop, often to the extent that it does not sink at all, but floats around the top of the aquarium. Goldfish also get constipated, just a little added TMI for you. Goldfish problems or illnesses are sometimes even diagnosed by poop – length, bubbles, color, etc. Think I’m kidding? Check out the link below for proof.
http://puregold.aquaria.net/disease/technique/technique.html#By poop
Ooooooooooooooooooooookay, I tried to preview this to see if the urls were okay, but it is taking 10,000 years to show up, so I’m just gonna hit submit.
Anyi,
FWIW, I thought you had a valid idea about methane possibly dissolving into the aquarium water rather than appearing as bubbles, so I did a little research and found this site.
Here is the relevant part:
…Polar molecules (with +/- charges) are attracted to water molecules and are hydrophilic. Nonpolar molecules are repelled by water and do not dissolve in water; are hydrophobic. Hydrocarbon is hydrophobic except when it has an attached ionized functional group such as carboxyl (acid) (COOH), then molecule is hydrophilic…
Methane is a hydrocarbon (composed of hydrogen and carbon atoms) and so would not be soluble. So if it is pure methane being released by fish, it would appear as bubbles without dissolving in the water. Maybe it’s not pure methane? <sigh> I guess it’s back to Google…
I’ve never seen any of the fish in my aquarium let one rip though- maybe they are just very polite?
I also have kept fish (goldfish) for approximately 20 years, and have noticed that, every once in a while, a bubble does appear in the fishes’ waste. I have always presumed that this was pretty much the same process for fish as for people. Maybe that’s a little anthropomorphic, but it seems pretty logical.
In response to that and Svinlesha’s claims of odd Swedish experiments I offer the following. I got it in one of those e-mails that circles the globe 20-times an hour and although I probably shouldn’t repost the whole thing here it does contain some fart related material. In addition, it shows just what kinds of weirdness the world’s scientists sometimes get up to (afterall…somebody had to spend the time to figure all this out). Most of it isn’t relevant to anything but I included it all for your reading enjoyment. I make no claims as to the accuracy of anything written here.