Why Do Dead Fish Stink?

[FishDad2]

OK, I know it's an off-beat question but I got up Sunday morning to have my 9 year old asked me why dead fish stink, and frankly I didn't have any answer. I'm not quite sure where the question came from, as I haven't had a fish die in quite some time, but he's 9, so who knows where these things come from.

He thinks it doesn't make any sense, since they're in the water all the time so it's like they're always taking a bath. How can they stink if they're always taking a bath dad?

Since I like to encourage him to ask questions...even stinky fish questions...I'd like to try to answer it if I can. So, does anyone have an explanation I can use? Just why do they stink so much?

[NicoleC]

Okay, I'll take a whack at it. It's one of those things you understand without knowing why, like why 8 is spelled eight.

Simple but real reason: they are rotting, which makes ammonia. Ammonia stinks. Their bodies also are decomposing into all the foods they have eaten and processed over their lifetime (more or less).

Tell him you are what you eat, and then offer some two day old shrimp for him to smell.

Isn't there a book for kids about his age called the Big Book of Why Things Work, or some such? Might be a good buy for his age (and your sanity.)

[Anthony Calfo]

True enough... and a fair question.

The ultra short answer is decomposition.

Perhaps a food analogy for your son would work well? Fresh milk versus spolied?

Ooh... I know. An analogy about flatulence! Grilled steak smells so savory when we eat it, but smells much less than savory when it comes out.

Just a suggestion.

[Anthony Calfo]

dang... she's good! Beat me to the punch again in cyberspace

Thanks Nicole as always... you are a gem to the hobby. Very special thanks for all your excellent efforts and input in this forum especially.

[NicoleC]

Great minds, eh?

However, the next question will be, "why do farts stink?"

[revrenhex]

Cause they come from your Butt!

[NicoleC]

The Classic Book

[Anthony Calfo]

an absolutely fabulous book on the subject for children and adults alike:

http://www.amazon.com/exec/obidos/tg...books&n=507846

I'm not kidding. Best book I've ever read on the subject (yes... I do read a very wide range of titles/topics)

Its a translation no less. Just a hoot of a good book on the subject.

[NicoleC]

LOL! Talk about a double post!

[Anthony Calfo]

OMG!!!!!!!!!!!! that is scary

[NicoleC]

Does this mean we're on the same reading level?

[Anthony Calfo]

Heck... I know we are. I'm just wondering if we are listening to the same music and wearing the same colored clothes at this point.

Are you listening to the Allman Brothers, drinking bourbon and sweet tea... typing with one hand and holding a scared looking hamster in the other one, too?

Man... that would just be uncanny.

[NicoleC]

Nope, Glenmorangie on the rocks with a cat lying on my lap trying to preventing me from either typing or getting up to walk the dog.

Hey, I'm the southerner -- what are you doing with sweet tea and bourbon?

[NicoleC]

P.S. I declare this thread officially hijacked.

[Anthony Calfo]

"Hey, I'm the southerner -- what are you doing with sweet tea and bourbon?"

I have good taste

And I also have a lap cat. Two in fact

[Anthony Calfo]

As for the hijacking... this thread has been given amnesty since the very title and topic are off-beat and flip/fun.

[Letmegrow]

Originally posted by Anthony Calfo

And I also have a lap cat. Two in fact

Maybe that's why the Hamster is nervous !

[daveonbass]

Originally posted by NicoleC
Great minds, eh?

However, the next question will be, "why do farts stink?"

I always thought it wa the E-Coli in our digestive tract that made the poopy smell so bad. E-Coli in general just smells like good skimmate...and worse.

[FishDad2]

Wow...17 replies so far...holy cow!!! or holy fish...whichever you prefer.

Thanks all...it a pretty funny thread...and helpful in its own special way.

Ok, decomposition is easy enough. But, anticipating his response when I tell him that after school today, he's going to say something like, "Isn't steak rotting too? Why does fish smell so much worse than steak?" And trust me, if explain what steak eats, he'll just keep coming until he finds a land animal that eats stinky stuff...don't forget, he's 9.

Now, I could go with Nicole's "you are what you eat" and point out the stinky shrimp example, but then he's going to want to know why the shrimp stinks...and why what they eat stinks...and so on down the food chain. Eventually, he'll want to know why everything in the ocean stinks so bad when it's dead.

Which leads us back to his initial question of, why do dead fish (or anything from the ocean for that matter) stink so bad? Is less to do with simple decomposition and more to do with the speed at which they decompose? Fish, and sea creatures in general, do breakdown much faster than land animals, no? Isn't that why you can't leave a piece of fish on the counter for very long before it becomes inedible, whereas a steak gives you a wider margin for error in that regard?

So, perhaps the answer is in why sea critters break down so much faster than land critters. But why is that? I don't have a clue...do you?

Oh yeah, and let's not get him started on farts...please...he's 9...he already lives for every possible opportunity to reference farts, the last thing I need is to give him more reasons to do so. "But mom, dad bought me the big book of farts..." I can my wife just glaring at me and shaking her head already. Hhhhmmmm....nope...don't see that as part of my response ;-)

[M.Maddox]

It's all about the bacteria that are decomposing the protein, sugars, fats, etc. Bacteria excrete enzymes to dissolve the protein in the meat they're breeding on, to liquify and allow them to uptake it for energy. This in turns causes an outgassing of wastes by the bacteria, and that the fact that our nose\brain detects this as noxious, for survival reasons (eg. if we were to eat this in the wild, we probably wouldn't survive, thus we avoid it). If it weren't for bacteria, nothing would ever be decomposed. Plus, when an animal dies, it's tissues are no longer protected, thus oxidation occurs (chemical attacks on the tissue from oxygen and other caustic gasses in our atmosphere) that also break down the protein, albeit slowly. Most don't realize this, but oxygen (and to a much larger extent, ozone) is incredibly caustic and facilitates the destruction of many compounds. If you really want to go into detail, the UV being shot into a normal aquarium will also facilitate the destruction of tissue, though at a much slower rate than the bacteria.

To add yet another reason, sugars (aka a few simple compounds of O, H, and C) are going to be decomposed by the "yeast" family of bacteria into CO2 and alcohol, which in turn is going to be metabolized by other species of bacteria, and the cycle continues.

The reason different meats\anything smell different as they decompose is due to both their composition and their environment. You're obviously going to find different bacteria species in a marine aquarium then you will in on that steak in your refrigerator, and those meats are going to be slightly different in their composition, as well. Plus, they're going to decompose at a different rate due to the ambient temperature (which of course, is why we have refrigerators in the first place).

There's a lot more to know - if you really want to go in-depth, take a college biology\chemistry course, or get the appropriate books. I also make no guarantees to the accuracy, it's been a few years since bio1\2

Hope this helped!

[hex1]

just a theory but could it be that fish decompose so fast because they are always surrounded by bacteria laden water? so the instant their immune system quits the bacteria attack in a frenzy since they are already on the animal, whereas a land animal has thick dry skin which is harder for bacterial to grow on. therefore the bacterial decomposition will usually start from the inside out. due to thebacteria heat and moisture in the intestines

[Hobster]

Three levels of Stink:

http://tishasharpthewriter.blogspot....unk-stank.html

[MCary]

Although E-coli is the most abundant aerobic bacteria in the digestive tract, anaerobic bacteria are 2000 times more plentiful. Anerobic bacteria are also incredibly more stinky. A couple of the things that make farts stink is methane and hydrogen sulfide.

[FishDad2]

ok...so the version for the 9 year old (which is where this whole thing started) is that:

1. bacteria in and on the fish break down all the tissue in the body...muscles, skin, etc...and that the bacteria give off the smell (hereafter referred to as "stink") as they convert the tissue to energy (digest)

2. fish are especially stinky when they die relative to other animals because they have lots more of the these bacteria and so the cells/tissue breakdown really fast...hence making lots-o-stink

3. the ocean is a very wet place and bacteria like the wet...so, more wet means more bacteria...more bacteria means more stink

Think I got it now...and even if I don't, this will answer his questions...he can go to college and let the professor correct him if I'm wrong.

Thanks to all the contributors in this festival of stink!!

[Surf]

I don't think the fish have more bacteria pre-death. Most living organisms are pretty bacteria free.

One thing that I think the collective missed was that fish proteins break down faster than mammilian proteins, and when they break down they form triethylamine, other meats do not. triethylamine is the stink.