# Do fish urinate?



## chirpchirp (Jan 6, 2013)

I understand this is probably a totally stupid question but i'm honestly wondering... Do fish pee / urinate?

thanks for the answers to my silly question in advance 
_Posted via Mobile Device_


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## MoneyMitch (Aug 3, 2009)

chirpchirp said:


> I understand this is probably a totally stupid question but i'm honestly wondering... Do fish pee / urinate?
> 
> thanks for the answers to my silly question in advance
> _Posted via Mobile Device_


im thinking their poo acts as both, but thats just a guess


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## chirpchirp (Jan 6, 2013)

See I have guppies, and when they are nearing birth / during birth you can see a clear fluid coming out i'm a small stream so to speak from the anal area. I've always figured it is some type of embryonic fluid or simply much like a human before birth the mothers water breaks I have been looking at it like that.
However yesterday I thought I saw my male doing it too. It was however a much smaller amount and not for a prolonged time or anything so I have just been wondering. Sometimes I have seen females (pregnant and non) do it also which has simply made me wonder 
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## Olympia (Aug 25, 2011)

No I don't think so.. Fish expel ammonia (though mostly through the gills I believe) and we expel urea (which is ammonia with carbon dioxide)..


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## chirpchirp (Jan 6, 2013)

As a human nurse I think I am looking at comparisons of humans to fish a lot hence my "like humans do" analogies but i'm sure there is some form of explanation.
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## jaysee (Dec 9, 2009)

Olympia said:


> No I don't think so.. Fish expel ammonia (though mostly through the gills I believe) and we expel urea (which is ammonia with carbon dioxide)..


Fish get rid of ammonia via the gills. However, it's done by passive diffusion. That means that the ammonia concentration of the fish can not be less than that of the water


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## rexpepper651 (Dec 25, 2012)

cool! i thought they were like birds lol


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## chirpchirp (Jan 6, 2013)

Lol the brown is poop and white is urine equivalent in birds I think. 
So what is this fluid I am seeing come out. Urination not ammonia related?
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## Quantum (Jul 23, 2011)

the do, and especially freshwater fish, must excrete urine, but not as the primary way of removing nitrogenous waste as has been mentioned, but as part of osmoregulation


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## chirpchirp (Jan 6, 2013)

So that is most likely what I an seeing? If you imagine a petrol slick how it looks like thick water almost that's the best way to describe it that I can think of right now that might be the stuff.
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## JDM (Dec 9, 2012)

They do, very prolific pee-ers, up to a third of their body mass per day. It's not something that many like to think about when playing in the tank water. :roll:

Jeff.


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## chirpchirp (Jan 6, 2013)

I said that to my fiancé and he laughed at me the other day and said I was playing in pee!
Still don't know of that I'd what I am seeing have had no confirmation or otherwise but who knows... God knows.when ever I have a chance i'm on the chair infront of the tank admiring its occupants but it is certainly something you would have to look closely at to see
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## JDM (Dec 9, 2012)

Yah, just think, if you peed out a third of your body weight each day, it would most certainly look like water. I know when I was drinking a Canadian gallon of water a day, well.... you can figure out the rest.:roll:

This is one of the reasons that water stability and correctness for the fish is so important. 

Jeff.


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## chirpchirp (Jan 6, 2013)

Haha I don't know how much a Canadian gallon is, I didn't even know it was different from a standard gallon 
Also most likely because we use the metric system.

It looks like thick water but the petrol thing my analogy is like the way you can see it you know how its almost shiney like an oil slick in the ocean but its clear. Looks thick though
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## Quantum (Jul 23, 2011)

the urine is very dilute with less solute conc than the surrounding water, so what you are seeing is likely due to light being refracted at the boundary of the different solutions, the effect of which diminishes as the two mix


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## jaysee (Dec 9, 2009)

Just curious - where did you see that guppies urinate a third of their body mass?


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## JDM (Dec 9, 2012)

chirpchirp said:


> Haha I don't know how much a Canadian gallon is, I didn't even know it was different from a standard gallon
> Also most likely because we use the metric system.
> 
> It looks like thick water but the petrol thing my analogy is like the way you can see it you know how its almost shiney like an oil slick in the ocean but its clear. Looks thick though
> _Posted via Mobile Device_


We use metric but the gallon is the imperial gallon which is larger than the US gallon.

1 imp gallon = 4.55 l
1 US gallon = 3.79 l

Jeff.


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## chirpchirp (Jan 6, 2013)

I see, we don't use gallons here really. So I wonder when packages here say dosages would it be us or imperial? I would think imperial but perhaps not
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## JDM (Dec 9, 2012)

The North American aquarium industry seems to use US gallons. I doubt it makes that much of a difference when using supplements or treatments as most seem to "allow" for three, four and five times overdosing levels anyway. I suspect that it is not an exact science.

Jeff.


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## MoneyMitch (Aug 3, 2009)

Quantum said:


> the urine is very dilute with less solute conc than the surrounding water, so what you are seeing is likely due to light being refracted at the boundary of the different solutions, the effect of which diminishes as the two mix


you confuse me lol


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## JDM (Dec 9, 2012)

MoneyMitch said:


> you confuse me lol


The water and pee are different densities which creates the "oil in water" effect as the light bends through the two fluids before they mix. 

Jeff.


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## Byron (Mar 7, 2009)

jaysee said:


> Just curious - where did you see that guppies urinate a third of their body mass?


I don't know if there is a significant difference between species when it comes to urine released, since it is, as Quantum mentioned earlier, related to osmoregulation. I do know that tetra can expel this much daily.

Urination is the fish's way of getting rid of all the water it takes in via osmosis through the cells, and this is partially determined by the TDS (total dissolved solids, which incudes the GH) in the tank water, one reason why this is so critical. If anyone wants to read a bit further on this, in fairly simple terms, check out my article on the effects of TDS as it it significant to this,
http://www.tropicalfishkeeping.com/...al-solids-tss-tds-freshwater-aquarium-122027/
and my article on Stress mentions it too:
http://www.tropicalfishkeeping.com/freshwater-articles/stress-freshwater-aquarium-fish-98852/

Byron.


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## JDM (Dec 9, 2012)

jaysee said:


> Just curious - where did you see that guppies urinate a third of their body mass?


It wasn't specifically guppies and I couldn't find it again... one of those articles that mentioned how much while describing the process and why it was so much, in reference to freshwater fish generally.

I never used to keep links to interesting articles but it would be handy when commenting to provide reference... I've started doing so more recently though. Nice to be able to go back and re-read some of them. Sometimes finding it the second time is easier said than done.

Jeff.


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## jaysee (Dec 9, 2009)

Byron said 3 times in his writeup he linked - I didn't read the reference to see how that was derived yet.


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## kaedeb (Mar 17, 2013)

I would think so, my guess their pee is clear of course because of the water they drink and filter. If you drank water all your life or for one day you will pee clear. So my guess is that they do.


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