Nitrite toxicity discussion

[Caliban07]

I've been doing some research on some scientific papers regarding the toxicity of nitrite to fish. Granted I haven't found many papers and there doesn't really seems to be any conclusive studies on this topic.

In the link I will provide the conclusions I have gathered are that nitrite toxicity is completely dependent on species and size of fish. Also amounts of chloride and bicarbonate present in the environment and levels of dissolved oxygen.

The article also describes how fish have a natural mechanism or reductase cells that reverse the formation of methemoglobin as it is accumulating. The lethality of nitrite is dependent on how well the species can do this. It also says that all fish have some levels of methemoglobin present in the cells as a percentage and that the starting percentage is dependent again on species.

There is also a chloride offset. My tap water report shows I have 5.85mg/l of chloride and I worked out that this would offset nitrite by around 2-2.5ppm according to this page.
If taking in to consideration the size of my fish and the species (impossible to study all species) and their background methemoglobin (percentage of meth already in cell) coupled with the ability of the species reductase cells to reverse the process. This could explain why some people have experienced elevated levels if nitrite with no consequence.

I'm still trying to figure out what levels of nitrite would be considered dangerous. This link seems to suggest nitrite levels of 1ppm upwards. But with everything else mentioned taken in to consideration I don't think it would come as a surprise to me that in some cases aquarium fish have survived higher concentrations.

I would always encourage people to change water in the event of nitrites and I'm not saying that it should be taken any less seriously. I was just wondering what your thoughts were and if you had any other papers that would provide an interesting read.

If fish in cycles are constantly reading levels of 0.25ppm on an API master test kit for example that would equate to around 0.6ppm nitrite. After 2 days the accumulation would already be over 1ppm nitrite early in the cycle but my fish never shown any distress.

I just find this interesting. It's difficult to know if nitrite accumulation has caused a fishes death because you would need ammonia which would most likely do the damage first.

Here the link http://ciresweb.colorado.edu/limnology/pubs/pdfs/Pub079.pdf

Feel free to blow my thoughts out of the water or add anything else.

 

[threnjen]

I haven't read ANY of these but here are my bookmarks on this topic.

http://www.aces.edu/dept/fisheries/aquaculture/documents/BrownBlood.pdf
Recent advances in fish toxicology: a symposium - Corvallis Environmental Research Laboratory, United States. Environmental Protection Agency. Office of Research and Development - Google Books
http://www-heb.pac.dfo-mpo.gc.ca/congress/1994/tomasso.pdf
http://actavet.vfu.cz/pdf/200574010129.pdf
http://www.agriculturejournals.cz/publicFiles/61325.pdf

Here are some studies all about Danios, our favorite hardy cycling fish:
http://actavet.vfu.cz/pdf/200675010107.pdf
http://actavet.vfu.cz/pdf/200574030435.pdf
http://actavet.vfu.cz/pdf/200877030455.pdf
http://actavet.vfu.cz/pdf/201180030309.pdf
Nitric oxide formation from nitrite in zebrafish



Have some reading material!
I will get started on these

 

[Caliban07]

I haven't read ANY of these but here are my bookmarks on this topic.

http://www.aces.edu/dept/fisheries/aquaculture/documents/BrownBlood.pdf
Recent advances in fish toxicology: a symposium - Corvallis Environmental Research Laboratory, United States. Environmental Protection Agency. Office of Research and Development - Google Books
http://www-heb.pac.dfo-mpo.gc.ca/congress/1994/tomasso.pdf
http://actavet.vfu.cz/pdf/200574010129.pdf
http://www.agriculturejournals.cz/publicFiles/61325.pdf
http://actavet.vfu.cz/pdf/200877030455.pdf

Here are some studies all about Danios, our favorite hardy cycling fish:
http://actavet.vfu.cz/pdf/200675010107.pdf
http://actavet.vfu.cz/pdf/200574030435.pdf
http://actavet.vfu.cz/pdf/200877030455.pdf
http://actavet.vfu.cz/pdf/201180030309.pdf
Nitric oxide formation from nitrite in zebrafish

Your search engine is better than mine lol.

I have a whole lot of reading to do. Thanks threnjen.

 

[threnjen]

http://www.aces.edu/dept/fisheries/aquaculture/documents/BrownBlood.pdf
First article

This one has interesting info on nitrite toxicity protection by sodium chloride (table salt). We've heard of this before, but this one offers that the fish are protected at a ratio of 9:1 sodium chloride to nitrites. Meaning for every 1ppm nitrites, you need 9ppm sodium chloride in order to protect the fish.
I've seen other papers that provide a "maximum" protected level that sodium chloride can protect to (and after that the nitrite is just toxic), but this particular paper just stresses the 9:1 ratio. Its example problems use 8ppm nitrite to calculate 72ppm salt for protection.
It's also worth noting that they simply talk about table salt and not some fancy aquarium salt, although I would venture you would want to use iodine-free. I know that a lot of the old-timers poo-poo the whole "aquarium salt" thing and it really does seem to be a fancy repackaging of the same old thing.

"Farmers who routinely maintain a minimum of 60-150 ppm of chloride in water at all times seldom experience losses from nitrite build-up and effectively prevent nitrite poisoning"

 

[threnjen]

Your search engine is better than mine lol.

I have a whole lot of reading to do. Thanks threnjen.

I just have mad research skillz

 

[threnjen]

Question: Is nitrite dangerous to fish SOLELY because it reduces oxygen in the blood and makes them suffocate?

On another note:
I wanted to know how much table salt was required to increase to 100ppm. I filled a 1 gallon jug (3.79L) with my tap water. I used my TDS meter to check dissolved solids (18ppm). I added 1 tsp salt (about 6g). TDS was then 208, so even that was overkill. It's approximately 1/2 tsp per gallon, or 3g per gallon, or 4g/5L to add 100ppm sodium chloride.

This is all approximate, I grabbed my not-most-accurate scale. I actually have a scale that goes to hundredths of a gram but I was too lazy to grab it. If we come up with some actual recommendation for the newbies I will use it to get a more accurate reading.

It would honestly be really helpful to be able to confidently assert to the fish-in people that they should add salt during the nitrite phase.

 

[Caliban07]

Question: Is nitrite dangerous to fish SOLELY because it reduces oxygen in the blood and makes them suffocate?

On another note:
I wanted to know how much table salt was required to increase to 100ppm. I filled a 1 gallon jug (3.79L) with my tap water. I used my TDS meter to check dissolved solids (18ppm). I added 1 tsp salt (about 6g). TDS was then 208, so even that was overkill. It's approximately 1/2 tsp per gallon, or 3g per gallon, or 4g/5L to add 100ppm sodium chloride.

This is all approximate, I grabbed my not-most-accurate scale. I actually have a scale that goes to hundredths of a gram but I was too lazy to grab it. If we come up with some actual recommendation for the newbies I will use it to get a more accurate reading.

It would honestly be really helpful to be able to confidently assert to the fish-in people that they should add salt during the nitrite phase.

Interesting stuff. There was a bit that mentioned calcium can increase the effect of chloride also. still I added 0 salt during my fish in cycle and my fish were ok. I didnt observe any reading of nitrite although testing was sporadic. It will be interesting to read the danio paper as this will be closer to the species we are used to seeing in our aquarium. I agree salt during a fish in that has gone wrong would be recommended so far. And maybe the addition as a preventative would aslo be helpful.

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[Caliban07]

The 96hLC50 for smaller fish (average weight 4.4 ± 1.50
g) was 266.17 mg·l-1 NO2- and larger fish (90.7 ± 16.43 g) demonstrated 96hLC50 of 26.29 mg·l-1 NO2-. Nitrite doesnt come close to these levels in our aquariums

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[threnjen]

Did you read the one about danios and guppies? The danios had really high resistance like 250+ but the guppies were around 20. That water had a bunch of NaCl added to it to protect them.
I haven't read all the papers yet,been distracted.

I didn't realize that NaCl was so important. That original paper you posted is one I have read before but I see now that basically ALL of the papers advocate NaCl addition to protect from toxicity.

 

[Caliban07]

The first of the danio links has a graph. The tested 20-25 day old danios against 2-3 months old danios.

Chloride levels at the lowest level of 19mg/l indicated that the 96 hour mean lethel concentration was near the 200mg/l mark

Thats a lot of nitrite needed to kill half the danio population.

Sent from my SM-T210 using Aquarium Advice mobile app

 

[Caliban07]

Yes chloride is very important. But like I said. I have 5.5mg/l in my tap water and nitrites have never been close to reaching even 1ppm. According to this even if I have less than a third chloride in my tap the concentrations we are talking about in my our aquarium is minuscule compared to these test levels

 

[Caliban07]

If I had 0.25 tan ammonia constantly for 2 weeks this would produce 9.45ppm nitrites. Granted the bacteria would have already started on this in reality. But say I had 0 nitrospira.

9.45ppm nitrite is like 4.7% of the levels needed to start killing 50% of the 2-3 months old danios. Granted chloride levels were nearly 4 x higher than my tap but can you see where I'm going with this?

 

[threnjen]

Yeah, although I think you should use guppies as your baseline for research. We all know danios are hardiest, but a lot of the newbies just throw in whatever fish strikes their fancy at the shop.

 

[Caliban07]

Yeah, although I think you should use guppies as your baseline for research. We all know danios are hardiest, but a lot of the newbies just throw in whatever fish strikes their fancy at the shop.

Yes, I haven't got to that link yet. My football team have a very important game today so I'm off to watch it Will continue later.

 

[Hondatek]

Here is a link explaining nitrite toxicity in saltwater... or the lack of it . Surprisingly nitrite is not toxic in saltwater like many believe it to be.

Nitrite and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

 

[J.Mcpeak]

Just add salt is a bad idea! It may solve nitrite but it may cause more problems elsewhere, if the system is cycling still it could be a disaster. I will elaborate,

Cases against Soft water acidophiles and cycling systems.
>
To increase the water hardness, you will instead need some Epsom salt and calcium chloride. Epsom salt is the market name for hydrated MgSO4 and adding 1 milliliter of it per 10 liters of water will increase the permanent hardness by roughly 70 mg/L CaCO3. You may however wish to increase the calcium (Ca++) contribution to hardness as well and this can be achieved by using a marine salt mix or calcium chloride. It may feel strange to add salt to a freshwater set up, but you only have to add a really small amount of salt to increase the calcium content to suitable levels for African Rift Valley cichlids and other calcium loving freshwater species. Such a small amount of salt will not harm fish species used to hard water. Pure calcium chloride will naturally also increase the calcium content, but calcium chloride is normally must more difficult to come by than a marine salt mix. Instead of picking it up in the pet store, you may have to order it directly from a chemical supply store.

>
The effect of pH variation, within the range 6.5, 7.0, 7.5, 8.5 and 9, on activated sludge denitrification of a synthetic wastewater containing 2700 mg/l NO3-N was examined using bench-scale Sequencing Batch Reactors. Two major effects were observed. One, at pH values of 6.5 and 7.0, denitrification of a synthetic wastewater containing high nitrate levels was significantly inhibited. Two, denitrification was achieved at higher pH values of 7.5, 8.5 and 9.0, but the accumulation of nitrite increased significantly as mixed liquor pH increased with peak values of 250, 500 and 900 mg/l NO2-N, respectively. As the pH rose, the specific rate of nitrate reduction increased. At the same time the specific rate of nitrite reduction increased in the absence of nitrate. In the presence of nitrate the specific rate of nitrite reduction remained constant, and the degree to which nitrite reduction increased in the absence of nitrate was a function of increasing pH. While increasing pH from 7.5 to 9.0 affected nitrite intermediate accumulation, the overall time for complete denitrification (reduction of both NO−3 and NO−2) was similar for the pH values of 7.5, 8.5 and 9.

Salt will only work in a nitrate free environment and not for all fish species.

>
Ammonia is a nitrogen waste released by aquatic animals into the production pond environment. It is a primary byproduct of protein metabolism. Ammonia is excreted directly from the fish gill into the water. Ammonia concentrations are usually at their highest late in the production season when biomass of the cultured species and the amount of protein fed are greatest. Ammonia is toxic to aquatic life and toxicity is affected by pond pH. Ammonia-nitrogen (NH3-N) has a more toxic form at high pH and a less toxic form at low pH, un-ionized ammonia (NH3) and ionized ammonia (NH4+), respectively. In addition, ammonia toxicity increases as temperature rises.

The daily interplay of photosynthesis and respiration creates a cyclical change in pond pH. Pond water becomes most acidic just before the period of darkness ends and most alkaline after several hours of daylight. The presence of un-ionized ammonia, the toxic form, increases as pH rises and decreases as pH falls which causes ammonia to become more ionized. The concentration of un-ionized ammonia in production ponds is lowest just before dawn and highest late in the afternoon.

This has significant implications for water quality monitoring, especially several weeks prior to harvest when fish biomass is greatest. For example , a producer measures water quality at 0400 hr. The total NH3-N concentration is 2.7 mg/L, pH is 7.0, and water temperature is 28 oC. The farmer then cross-references these values with a standard, pH-temperature table and calculates the concentration of “un-ionized” NH3-N to be 0.019 mg/L. The producer decides to check water quality again at 1600 hr and finds that total NH3-N is still 2.7 mg/L. But, pH and water temperature have risen to 9.0 and 30 oC. After checking the reference table, the farmer discovers that the un-ionized NH3-N concentration is now 1.2 mg/L. An un-ionized NH3-N level of 0.019 mg/L would be considered acceptable for channel catfish production. However, the un-ionized NH3-N concentration of 1.2 mg/L recorded at 1600 hr could be lethal to channel catfish within several hours. Over a 12-hr period, the un-ionized ammonia concentration increased approximately 63-fold. The temperature change accounts for less than 10% of the increase in toxicity while the rise in pH from 7.0 to 9.0 is responsible for more than 90%.


The measure of whether water is acidic, basic (alkaline) or neutral is known as pH. A scale of 1 to 14 is traditionally used, which represents the negative logarithm of the hydrogen ion concentration. A pH of 7.0 is neutral; above 7.0 is basic and below 7.0 is acidic; close to 7.0 is weak and far from 7.0 is strong. It is a common perception that the pH of water is neutral and constant at a value of 7.0. In an environment free of carbon dioxide, aquatic life, and compounds other than H2O; pond pH would remain 7.0 or neutral. However, this combination of conditions is unlikely to occur on our planet. The pH of water is naturally acidic because the atmosphere contains carbon dioxide (CO2). Carbon dioxide readily dissolves into water, raindrops and other sources of water exposed to air, forming a weak acid (H2CO3, carbonic acid). Therefore, events in the aquatic environment that affect CO2 concentrations also affect pH. There are minerals in soil that can dissolve in water to create acidity and alkalinity as well.

(Cited from various references)

.....I'm along for the ride!

 

[J.Mcpeak]

Here is a link explaining nitrite toxicity in saltwater... or the lack of it . Surprisingly nitrite is not toxic in saltwater like many believe it to be.

Nitrite and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

This chap is excellent, a must read for anyone who hasn't yet. While the title suggests reef systems he actually covers a lot of freshwater ground.

 

[Caliban07]

Just add salt is a bad idea! It may solve nitrite but it may cause more problems elsewhere, if the system is cycling still it could be a disaster. I will elaborate,



Cases against Soft water acidophiles and cycling systems.

>

To increase the water hardness, you will instead need some Epsom salt and calcium chloride. Epsom salt is the market name for hydrated MgSO4 and adding 1 milliliter of it per 10 liters of water will increase the permanent hardness by roughly 70 mg/L CaCO3. You may however wish to increase the calcium (Ca++) contribution to hardness as well and this can be achieved by using a marine salt mix or calcium chloride. It may feel strange to add salt to a freshwater set up, but you only have to add a really small amount of salt to increase the calcium content to suitable levels for African Rift Valley cichlids and other calcium loving freshwater species. Such a small amount of salt will not harm fish species used to hard water. Pure calcium chloride will naturally also increase the calcium content, but calcium chloride is normally must more difficult to come by than a marine salt mix. Instead of picking it up in the pet store, you may have to order it directly from a chemical supply store.



>

The effect of pH variation, within the range 6.5, 7.0, 7.5, 8.5 and 9, on activated sludge denitrification of a synthetic wastewater containing 2700 mg/l NO3-N was examined using bench-scale Sequencing Batch Reactors. Two major effects were observed. One, at pH values of 6.5 and 7.0, denitrification of a synthetic wastewater containing high nitrate levels was significantly inhibited. Two, denitrification was achieved at higher pH values of 7.5, 8.5 and 9.0, but the accumulation of nitrite increased significantly as mixed liquor pH increased with peak values of 250, 500 and 900 mg/l NO2-N, respectively. As the pH rose, the specific rate of nitrate reduction increased. At the same time the specific rate of nitrite reduction increased in the absence of nitrate. In the presence of nitrate the specific rate of nitrite reduction remained constant, and the degree to which nitrite reduction increased in the absence of nitrate was a function of increasing pH. While increasing pH from 7.5 to 9.0 affected nitrite intermediate accumulation, the overall time for complete denitrification (reduction of both NO−3 and NO−2) was similar for the pH values of 7.5, 8.5 and 9.



Salt will only work in a nitrate free environment and not for all fish species.



>

Ammonia is a nitrogen waste released by aquatic animals into the production pond environment. It is a primary byproduct of protein metabolism. Ammonia is excreted directly from the fish gill into the water. Ammonia concentrations are usually at their highest late in the production season when biomass of the cultured species and the amount of protein fed are greatest. Ammonia is toxic to aquatic life and toxicity is affected by pond pH. Ammonia-nitrogen (NH3-N) has a more toxic form at high pH and a less toxic form at low pH, un-ionized ammonia (NH3) and ionized ammonia (NH4+), respectively. In addition, ammonia toxicity increases as temperature rises.



The daily interplay of photosynthesis and respiration creates a cyclical change in pond pH. Pond water becomes most acidic just before the period of darkness ends and most alkaline after several hours of daylight. The presence of un-ionized ammonia, the toxic form, increases as pH rises and decreases as pH falls which causes ammonia to become more ionized. The concentration of un-ionized ammonia in production ponds is lowest just before dawn and highest late in the afternoon.



This has significant implications for water quality monitoring, especially several weeks prior to harvest when fish biomass is greatest. For example , a producer measures water quality at 0400 hr. The total NH3-N concentration is 2.7 mg/L, pH is 7.0, and water temperature is 28 oC. The farmer then cross-references these values with a standard, pH-temperature table and calculates the concentration of “un-ionized” NH3-N to be 0.019 mg/L. The producer decides to check water quality again at 1600 hr and finds that total NH3-N is still 2.7 mg/L. But, pH and water temperature have risen to 9.0 and 30 oC. After checking the reference table, the farmer discovers that the un-ionized NH3-N concentration is now 1.2 mg/L. An un-ionized NH3-N level of 0.019 mg/L would be considered acceptable for channel catfish production. However, the un-ionized NH3-N concentration of 1.2 mg/L recorded at 1600 hr could be lethal to channel catfish within several hours. Over a 12-hr period, the un-ionized ammonia concentration increased approximately 63-fold. The temperature change accounts for less than 10% of the increase in toxicity while the rise in pH from 7.0 to 9.0 is responsible for more than 90%.





The measure of whether water is acidic, basic (alkaline) or neutral is known as pH. A scale of 1 to 14 is traditionally used, which represents the negative logarithm of the hydrogen ion concentration. A pH of 7.0 is neutral; above 7.0 is basic and below 7.0 is acidic; close to 7.0 is weak and far from 7.0 is strong. It is a common perception that the pH of water is neutral and constant at a value of 7.0. In an environment free of carbon dioxide, aquatic life, and compounds other than H2O; pond pH would remain 7.0 or neutral. However, this combination of conditions is unlikely to occur on our planet. The pH of water is naturally acidic because the atmosphere contains carbon dioxide (CO2). Carbon dioxide readily dissolves into water, raindrops and other sources of water exposed to air, forming a weak acid (H2CO3, carbonic acid). Therefore, events in the aquatic environment that affect CO2 concentrations also affect pH. There are minerals in soil that can dissolve in water to create acidity and alkalinity as well.



(Cited from various references)



.....I'm along for the ride!

Yeh I read about ph and photosynthesis. Think I actually read that article. I'm not a huge fan of adding salt direct to the aquarium. Just salt dips. How much nitrate are we talking here to disrupt the affect of nitrite inhibition? We are on a much smaller scale here.

 

[Caliban07]

By the way. Welcome! The more the merrier!

 

[threnjen]

Cases against Soft water acidophiles and cycling systems.
>
To increase the water hardness, you will instead need some Epsom salt and calcium chloride. Epsom salt is the market name for hydrated MgSO4 and adding 1 milliliter of it per 10 liters of water will increase the permanent hardness by roughly 70 mg/L CaCO3. You may however wish to increase the calcium (Ca++) contribution to hardness as well and this can be achieved by using a marine salt mix or calcium chloride. It may feel strange to add salt to a freshwater set up, but you only have to add a really small amount of salt to increase the calcium content to suitable levels for African Rift Valley cichlids and other calcium loving freshwater species. Such a small amount of salt will not harm fish species used to hard water. Pure calcium chloride will naturally also increase the calcium content, but calcium chloride is normally must more difficult to come by than a marine salt mix. Instead of picking it up in the pet store, you may have to order it directly from a chemical supply store.

I was personally talking about NaCl which is sodium chloride aka table salt. That doesn't add any magnesium or calcium to the water, although it does increase the TDS. However a TDS increase of 60-100ppm is something that most fish can tolerate.