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How does Ammonia "burn" gills?

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I know that ammonia can burn a fishes' gills, but exactly how does this happen?

Is it something along the lines of the NH3 reacting with the fishes' gill?
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just like any other chemical burn. If you were to pour bleach on your skin, it would burn. if I remember my chemistry, Ammonia is a heavy basic compound, which is the exact opposite of an acid and just as bad for harming living things.
 

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If someone sticks his/her nose into a bottle of ammonia and inhales, the sensation is similar to what happens to a fish's gills.
 

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Yeah, the tissue cells within the gills that not only absorb the oxygen, but excrete the ammonia from the fish body. They play 2 roles. So excreting ammonia, while taking it in is like us huffing on a tail pipe.
 

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A fish's gills have enormous surface area for gas exchange. They are used for infusing O2 into the bloodstream as well as expelling ammonia and CO2. Fishes (depending on freshwater or saltwater) excrete ammonia and/or urea through their anus as well as the gills. It all depends on the particular species' anatomy how much ammonia is expelled, but ammonia is always HIGHLY toxic but cheap to produce, vs. urea which is less toxic but costs a lot of energy to produce. Saltwater fishes have adapted to using urea more, but unfortunately freshwater fishes are 'behind' in still expelling more ammonia than urea.

Little info via my Ichthyology lecture this term. Interesting stuff! :) My instructor didn't go into detail on why ammonia is so toxic (covering mostly basic anatomy this term) but I would think it would have to be similar to what was previously mentioned, chemical burn.
 

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Interesting, Ashnic.

I know it's harder to excrete something through diffusion when there's already a lot of it in the water.

And I know that for humans, when ammonia builds up in the blood as a result of liver/kidney failure, it's lethal. And also very painful.

So for fish, death might not be strictly from burns to the gill tissue alone.
 

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I know it's harder to excrete something through diffusion when there's already a lot of it in the water.
True, which is why I think that the more ammonia there is in an aquarium, the harder it is for fish to breathe as they are spending most of their energy extracting as much O2 as possible (especially saltwater fishes) and ideally, they would spend less energy expelling ammonia.
 

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An acid or base is defined on what it does with one or more Hydrogen atoms. A donor, the substance that is likely to give off a Hydrogen atom is an acid. An acceptor, the substance that is likely to accept a Hydrogen atom is a base.

This is a simple explanation but it's not restricted to the Hydrogen atom as recent discoveries have shown.

NH3 does not cause burns as far as my knowledge goes, Chlorine and Chloramine are potent oxidizers that can cause burns

NH3 just doesn't care about cell membranes and tends to accumulate in the body and cause stress to the fish's excretory organs until they fail. Permanent damage can also occur as a result. Fish exposed to traceable amounts of Ammonia might be scared for life.

I'm no fish expert, just sharing what I gathered from my readings.
 

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NH3 just doesn't care about cell membranes and tends to accumulate in the body and cause stress to the fish's excretory organs until they fail. Permanent damage can also occur as a result. Fish exposed to traceable amounts of Ammonia might be scared for life.
I think NH3 would accumulate in the fish's body only if the amount of ammonia in the environment was so great the fish's gills would diffuse ammonia back into the fish's system. Could be wrong, but I'm still learning all this anyway. :)
 
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