Question Nitrate Toxicity In Fish

[BRANDON SHAFFER]

I am curious if anyone has personally experienced or heard of negative repercussions on fish health from high nitrate level. It is always said that nitrate should be kept below 40 mg/L, but why is this? Can anyone link a scientific study showing that amounts exceeding 40 mg/L for an extended period of time reduce lifespan, immune system efficiency, growth rate, oxygen saturation, etc.., of freshwater fish? Any input will be appreciated.

 

[Wraithen]

I am curious if anyone has personally experienced or heard of negative repercussions on fish health from high nitrate level. It is always said that nitrate should be kept below 40 mg/L, but why is this? Can anyone link a scientific study showing that amounts exceeding 40 mg/L for an extended period of time reduce lifespan, immune system efficiency, growth rate, oxygen saturation, etc.., of freshwater fish? Any input will be appreciated.

This is going to come across as bad but google scholarly articles nitrate toxicity freshwater.

There are reports on tons of studies and experiments. There are literally too many to list as it has been studied since 1965 at least.

Tldr: people use 40 because they are comfortable with it and it has been parroted forever. Long term exposure to much lower levels has shown damage in the wild.

 

[Jeffsglo]

Here is an article I found. Hope this helps. I have high nitrates in my tank now from my tap water. So I have ordered some Marimo Moss Balls from the local fish store to lower them. I will see if they help.

 

[Skavatar]

New-ish Nitrate Toxicity Study

Recently, there is increasing evidence that elevated nitrate can chronically impact the general health and performance of fish cultured in RAS.
https://www.sciencedirect.com/science/article/pii/S0144860917301231

Chronic nitrate exposure resulted in endocrine disruption
https://www.sciencedirect.com/science/article/pii/S0269749117313520#bib23

A significantly greater prevalence of “side swimming” rainbow trout was quantified for the high nitrate treatment.
•
Slightly slower growth and decreased survival resulted in significantly lower fish biomass for the high nitrate treatment.
•
High nitrate nitrogen (80–100 mg/L) was related to chronic health and welfare impacts to juvenile rainbow trout.
https://www.sciencedirect.com/science/article/pii/S0144860914000041#fig0025

A good baseline, in our opinion, lies at about the 95% resultant life expectancy point. This corresponds to a value of about 23.5 ppm NO3. A further study with zebrafish LC50 data gives us a value of about 21.1 ppm NO3 for the 95% life expectancy point. Note that this doesn't deviate much from the traditional recommendation of 20-40 ppm.
February Discussion Topic - Nitrate Toxicity : Aquariums

paid article, "Poor water quality kills more fish than infectious agents, making client education a very important preventive tool for aquatic practitioners. This article includes a discussion of toxicities related to water quality, chemotherapeutics, pesticides, and household substances."

 

[mimo91088]

I can't think of one, no. But it's so easy to keep under control with water changes that I wouldn't risk it.

 

[Brian Knowles]

Welcome Aboard. There are endless articles on all three common parameters, and how they affect fish. Many even go into depth on how they affect specific species and sub species.

 

[AquaticJ]

I think it’s important to realize just how bad nitrate exposure can be to fish, and humans. The EPA limits city water to only 10 ppm of nitrate, and that’s because of how bad it can be for us to drink. Now think about a fish constantly living in high nitrate, not just drinking it like us. Something to think about.

 

[BottomDweller]

My tap water has 80ppm nitrates. When i first started keeping fish the only ones i could keep alive were goldfish. My zebra danios, guppies and some other fish behaved oddly and slowly died off. I thought my tao water had no nitrates in (i just hadn't shook the bottle enough) so was confused about how the nitrates were so high in my tanks and why my fish were all dying.
I now use matrix in all my tanks and plant them as heavily as possible to lower nitrates. Most of my tanks now have around 20ppm nitrates and my luck with fish is much better.

 

[Whitewolf]

No nitrates at my local lake. But it has lots of weeds

 

[Islandvic]

Google search Dr. Kevin Novak then add combinations of the following: anoxic filtration, plenums, denitrification, koi filtration.

He is both a ichthyologist and limnologist and has studied nitrate reduction for some time. He has shared his knowledge on the subject of nitrates and their effect on ecology via online forums/posts and on his YouTube channel.

 

[Whitewolf]

It's usually plants, mosses or floating algae that eat to nitrates

Sent from my SM-S727VL using Fish Lore Aquarium Fish Forum mobile app

I am not sure about links, as this website usually dosent allow many links. Im sure you can google it, there have been plenty of research studies that prove fish in zero or low nitrates do much better than fish in 40ppm or more nitrate water.

 

[SFGiantsGuy]

An abundance of plants can and will soak up gargantuan amounts those nitrates, and also suck up other things such as ammonia, impurities etc. In time, a lot of plants can outdo the best water changes or any amount of syphoning/cleaning out our gravel, with an astonishing scale. Which is mainly why a ton of plants are utilized to purify our immediate, convenient, drinking water. However it is a debatable issue, and perhaps may never reach a satisfying and sufficient understanding--hence more of nature's wonders, and negatively as well, unfortunately as it may seem...

 

[happyscrub]

All fish react differently. Nitrates are like oxygen. Some fish evolved to survive bad conditions, others don't.

 

[Coptapia]

[post deleted as it wasn’t posted in this thread]

 

[AvalancheDave]

https://www.researchgate.net/profil...to_Nitrate/links/555eabeb08ae9963a1142908.pdf
This study found that exposing the Common Carp ((Cyprinus carpio) to 12ppm for 1, 2, and 4 days caused severe degeneration of the liver (which improved somewhat over time but remained damaged).

This one researched the kidneys...
https://www.bzu.edu.pk/jrscience/vol15no4/9.pdf

Both of those studies are very likely fake.

https://www.researchgate.net/profil...aquatic-species.pdf?origin=publication_detail
This one found that nitrate levels of well below 10ppm affect growth and development of salmon and trout, and a few other species.

Where does it say that?

As I said, data for ‘aquarium fish’ are few and far between, so far, but there’s a general concensus that nitrate is a causative agent in both Hole in the Head and Lateral Line Erosion diseases in cichlids. These diseases commonly occur at what we would historically call relatively low nitrate levels (<40), which are showing themselves to actually be ‘relatively high’.

Citation?

 

[Skavatar]

not sure why they would lie or make fake carp studies when carp is an important food source in Pakistan, and one of the few farmed fish in Pakistan.
"Freshwater carp farming is the major aquaculture activity in Punjab, Sindh and Khyber Pakhtunkhwa. The northern mountains of Pakistan have good potential for troutculture, but production is still very small. According to the latest estimates, the total area covered by fish ponds is about 60,500 ha in Pakistan, is 49,170 ha in Sindh, is 10,500 ha in Punjab, 560 ha in Khyber Pukhtunkhwa, and 240 ha in Balochistan, Gilgit-Baltistan and Azad Kashmir. More than 12,000 fish farms have been established across Pakistan. The average size of farm ranges form 6-9 ha. About 50,000 people are employed in the sector."
https://en.wikipedia.org/wiki/Fishing_in_Pakistan

page 17
"Camargo et al. (2005) recommend (p1264) “… a maximum level of 2.0 mg NO3-N/L would be appropriate for protection the most sensitive freshwater species”. This value is similar to that which we have derived using the ANZECC (2000) and the Environment Canada (CCME 2007) methodology with the updated chronic dataset. Notably, the Environment Canada (2003) derives a “interim” water quality guideline of 2.9 mg NO3-N/L 5."
approx 9ppm and 13ppm Nitrate respectively

pg 18
"As noted earlier, the ANZECC (2000) guidelines for nitrate contains errors in the derivation procedure, although Environment Canterbury has been using the corrected guideline value of 7.2 mg NO3-N/L2. However, our present more detailed review has identified further transcription/calculation errors from the original papers which were not cited in the 2002 review, including the use of potassium nitrate data (see Appendix 3). We have corrected those errors in this review and incorporated the corrected datain this derivation. The original ANZECC (2000) derivation was based on 12 nominal “acute” results with the use of an ACR of 10 to derive the guideline. This review includes updated and expanded data with chronic results for 15 species.
We would recommend that this revised nitrate guideline value for 95% protection of 1.7 mg NO3-N/L be used for Canterbury’s rivers and lakes. Site-specific consideration for seasonally varying background levels (1–3 months duration), could use the lower protection threshold of 3.6 mg NO3-N/L (80% protection value), if the seasonal period did not specifically serve sensitive species or life-stages, recognising that the remainder of the year would provide higher levels of protection."
approx 7.5ppm Nitrate for 95% protections and approx 16ppm Nitrate for 80% protection

 

[toosie]

High nitrate nitrogen (80–100 mg/L) was related to chronic health and welfare impacts to juvenile rainbow trout.
https://www.sciencedirect.com/science/article/pii/S0144860914000041#fig0025

This study at least specifies the format they use is Nitrate nitrogen, which means you have to multiply those results

(80–100 mg/L)

by 4.43 to convert them to the format we are used to, from using the API test kit which measure nitrate as nitrate. Not all studies are as clear and I am often left wondering which of the two (nitrate as nitrogen OR nitrate as nitrate) is being used.

I think it’s important to realize just how bad nitrate exposure can be to fish, and humans. The EPA limits city water to only 10 ppm of nitrate, and that’s because of how bad it can be for us to drink. Now think about a fish constantly living in high nitrate, not just drinking it like us. Something to think about.

Again, you need to multiply the EPA limit of 10 by 4.43 to convert it to the format we are use to.

So, I think these two forms of expressing nitrate levels need to be kept in mind and questioned whenever reviewing a study, to try to determine how that study is measuring nitrate levels, to better understand the results.

 

[AquaticJ]

This study at least specifies the format they use is Nitrate nitrogen, which means you have to multiply those results by 4.43 to convert them to the format we are used to, from using the API test kit which measure nitrate as nitrate. Not all studies are as clear and I am often left wondering which of the two (nitrate as nitrogen OR nitrate as nitrate) is being used.


Again, you need to multiply the EPA limit of 10 by 4.43 to convert it to the format we are use to.

So, I think these two forms of expressing nitrate levels need to be kept in mind and questioned whenever reviewing a study, to try to determine how that study is measuring nitrate levels, to better understand the results.

You’re doing it backwards

“Therefore, to convert Nitrate-NO3 (mg/L) to Nitrate-N (mg/L):
Nitrate-N (mg/L) = 0.2259 x Nitrate-NO3 (mg/L)
And to convert Nitrate-N (mg/L) to Nitrate-NO3 (mg/L):
Nitrate-NO3 (mg/L) = 4.4268 x Nitrate-N (mg/L)”

From his study, nitrate-NO3 (mg/L) is given as 80-100, lets just say 80 nitrate-NO3 (mg/L).

Nitrate-N (mg/L)= 0.2259 X 80
= Nitrate-N (mg/L)= 18.072 mg/L OR ppm

 

[Skavatar]

Toosie was correct.
"Levels of nitrate can be expressed in either of two ways: “nitrate as nitrogen” (symbol: NO3-N) or simply as nitrate (NO3). To convert NO3-N to NO3 in parts per million (ppm, or mg/L), multiply NO3-N by 4.42."

http://purewateroccasional.net/wtinitratesandnitrites.html

 

[toosie]

You’re doing it backwards

“Therefore, to convert Nitrate-NO3 (mg/L) to Nitrate-N (mg/L):
Nitrate-N (mg/L) = 0.2259 x Nitrate-NO3 (mg/L)
And to convert Nitrate-N (mg/L) to Nitrate-NO3 (mg/L):
Nitrate-NO3 (mg/L) = 4.4268 x Nitrate-N (mg/L)”

From his study, nitrate-NO3 (mg/L) is given as 80-100, lets just say 80 nitrate-NO3 (mg/L).

Nitrate-N (mg/L)= 0.2259 X 80
= Nitrate-N (mg/L)= 18.072 mg/L OR ppm

You are correct in the fact that you can use both sets of numbers, but I find that just confuses people, and you can just change the multiply to the divide to reverse the conversion.
But nitrate nitrogen does get multiplied by 4.43 to convert nitrate as nitrate.

From his study, nitrate-NO3 (mg/L) is given as 80-100, lets just say 80 nitrate-NO3 (mg/L).

But no...the study shows nitrate as nitrogen...

High nitrate nitrogen (80–100 mg/L) was related to chronic health and welfare impacts to juvenile rainbow trout.
https://www.sciencedirect.com/science/article/pii/S0144860914000041#fig0025

or at least that is how it is written here, which I assume was a quote from the link supplied with that statement. So if that is the case, the 80-100 would be multiplied by 4.43

But see... you are actually saying the exact same thing as I am here...

Nitrate-NO3 (mg/L) = 4.4268 x Nitrate-N (mg/L)

It's just that I think you let this two ways of converting confuse you. But what you wrote says... Nitrate-NO3 (which is a way of expressing nitrate as nitrate) = 4.426( which rounds to 4.43) X Nitrate-N (which is a way of expressing Nitrate as nitrogen) so this is the same equation as I used. The EPA use nitrate as nitrogen (Nitrate-N). API measures nitrate as nitrate (Nitrate-NO3).