NITRATES: At what levels do they cause a problems and how?

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philipraposo1982

philipraposo1982

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Feb 21, 2016
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Tonight I decided to test my nitrates (rare occasion) before I did a large water change. I started thinking about nitrates. Sure, I know they are bad but I have no idea how they effect the fish (aside from the common knowledge that they stress fish). But what is really happening inside their body when nitrates level start to rise.

At what levels are the nitrates causing damage to our fish? Is the 5ppm nitrates doing anything at all? Is like breathing a bit of pollution for us? Or is it actually shortening the life of our pets?

I am simply trying to understand the impact of nitrates on my pet. If its worse than I believe I will aim to keep sub 5ppm and maybe slack a bit if its not so bad. lets say aim for 10-15ppm.
 
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at .23ppm internal organ dmg starts to occur over time. this why we say to try and keep nitrates at 20ppm on the average. if you test your water and its above that water change. But once you know your creep having it 20 or 30 on water change day not a bad thing. On the average it is below that, if you water change at 60, or 70, or 140, well your late to the game and your fish have sustained some sort of dmg that will show up later in there life span.
 
and really that is all any basic fish keeper needs to know concerning nitrates, change the water, best thing you can do for your fish. if you are looking to fudge the numbers or water changes, well, maybe rethink having fish.
 
.23ppm or did you mean 23ppm? Also, what sort of internal organ damage are we talking about?

And just for the record, my GT is in my 75g which receives 3-4 water changes a week at 70% or more. I have been maintaining 0-5ppm nitrates.
 
I hardly ever test nitrates anymore these days. When I first started in the hobby I tested everything all the time, now I just follow a good water change schedule and there's no need to test anything unless I start to see some problems.

I'm a cichlid keeper so we overstock our tanks a bit to spread aggression so as usual most cichlid tanks nitrates will go up a tad more than others. With that said though I do 75% WC every 7-9 days on most my tanks. Nitrates hit about 40ppm when it's WC day.

Everyone has their thoughts on what is safe and not safe. 20ppm is not causing damage IMO I have never seen anything state that. 40ppm is about the normal threshold where a WC is needed. I have had mine hit 80ppm during vacation but that is only once per year and after I have been gone for 15 days.
 
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I know stingray breeders with constant 100-200 nitrates. They're breeding factories without problems. Pups born into and reared in 100+ levels, breeders over 12 years in age.
That said, I think a lot of the potential for damage is species specific. I also believe nitrates are much more toxic when present with ammonia and/or nitrite, than when present alone.

Maybe use the smoking analogy. It won't kill you today, but you stack up enough tomorrows, and eventually it's game over with the wrong species.

I'm on a very heavy drip with 0 nitrate source lake water. My levels are always minimum 20-40ppm as rays are enormous and eat pounds of raw fish daily. IME cichlids are very sensitive to nitrates (HITH and LLD), while catfish and stingrays, not so much.
 
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I read in an aquaculture magazine that in levels of 20ppm+ it stresses fish and their skin or gills are a more ideal substrate for bacteria to proliferate.

Fish vary. Such as discus will stunt very easily without stringent maintenance.

I just keep my tanks under 20 and that's that. Always had a reading in the 0-20 range since that's the lowest I can test
 
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