How toxic is ammonia, really?

[Randy Holmes-Farley]

In the context of trying to understand why so many people believe Seachem Prime was useful for them in an elevated ammonia situation, against the data in the link below about Prime potentially doing nothing to free ammonia in seawater, the question arises, why?

Does Prime actually "Detoxify" free ammonia, NH3?

This started when @Dan_P was looking at measuring NH3 with seneye and was curious about performance near zero NH3. I suggested trying Prime to artificially zero out the NH3 sensor, and the results were weird... so I checked with my seachem kit. Prime by Seachem is commonly used to treat tap...

www.reef2reef.com

One logical explanation is that folks really do not have a good understanding of how toxic ammonia is. They see 1 or 2 or 5 ppm total ammonia, dose Prime, the fish live, and they declare success.

But how toxic is it really? [note, there are always sublethal effects to toxins, and nowhere in this discussion am I advocating for elevated ammonia, I am focusing solely on the endpoint of death and how it relates to belief in whether Seachem Prime has "worked" in a given scenario]

In other words, what would have happened if they did not use Prime in the identical scenario.

We can use published scientific data on ammonia toxicity to gauge what might have happened.

Of course, every species of fish or invert ay have different ammonia tolerability, and pH also plays a strong role.

But let's explore some data.

Here's a 2019 review article published in INDIAN J. MAR. SCI., VOL. 48, NO. 03, MARCH 2019.

NIScPR Online Periodical Repository: Ammonia toxicity and adaptive response in marine fishes – A review

nopr.niscpr.res.in

The authors are at the University of Antwerp, Biology Department (Belgium) and the Central Marine Fisheries Research Institute in India. Thus, it is not a hobby publication, and they have already collected a fair number of previously published experiments to summarize.

Table 2 is what we want to look at.


Table 2 — Comparative toxicity of ammonia to various marine fish

Species TA-N (mgL-1) UIA-N (mgL-1)
4 -Day LC50 Sea bass 40 1.7
4 -Day LC50 Sea bream 57 2.5
4 -Day LC50 Turbot 59 2.6
4 -Day LC50 Cat fish 45 1.6
4 -Day LC50 Rainbow trout 22 0.3-0.6
8 -Day LC50 Sea bass >22.3 >0.9
20 -Day LC50 Sea bream 15.7 0.89
28 -Day LC50 Turbot 38 1
20-Day EC50 Sea bream 15.7 0.89
28-Day EC50 Turbot 17-19 0.50-0.65
55-Day EC50 Turbot 17-21 0.60-0.75
55-Day EC50 Sea bass 22 0.9
LC50 = Lethal concentration for 50% of the population
EC50 = Concentration reducing growth by 50%

Note the important measure: LC50. That is the concentration where 50% of the fish die in the indicated time.

ALL of the data supports the idea that few of these fish (much less than half) would die in 10-20 ppm total ammonia in 2 days. It takes 4 days in more than twice as much ammonia to kill even half of them.

That concentration is a long, long way above what most reefers would use as a trigger point for using Prime. So when fish survive, it may just be the expected result, whether Prime is added or not.

I don't want to make this initial post too long, so we can follow up with additional papers as they arise showing LC50 data for marine fish in seawater.

But I will note here that these results are typical, not an outlier. This paper shows similar results, where more than 1 ppm FREE ammonia is needed to kill half of a batch of silversides in 96 h. That translates to about 25 ppm total ammonia at pH 8.0.

The acute and chronic toxicity of ammonia to marine fish and a mysid - Archives of Environmental Contamination and Toxicology

The acute toxicity (96-hr LC50) of un-ionized ammonia to mysids (Mysidopsis bahia) and larval inland silversides (Menidia beryllina) was influenced by pH and salinity in a species specific manner. With mysids, NH3 was most toxic at pH 7.0 and less toxic at pH 8.0 and 9.0. In contrast, NH3...

link.springer.com

 

[MnFish1]

In the context of trying to understand why so many people believe Seachem Prime was useful for them in an elevated ammonia situation, against the data in the link below about Prime potentially doing nothing to free ammonia in seawater, the question arises, why?

Does Prime actually "Detoxify" free ammonia, NH3?

This started when @Dan_P was looking at measuring NH3 with seneye and was curious about performance near zero NH3. I suggested trying Prime to artificially zero out the NH3 sensor, and the results were weird... so I checked with my seachem kit. Prime by Seachem is commonly used to treat tap...

www.reef2reef.com

One logical explanation is that folks really do not have a good understanding of how toxic ammonia is. They see 1 or 2 or 5 ppm total ammonia, dose Prime, the fish live, and they declare success.

But how toxic is it really? [note, there are always sublethal effects to toxins, and nowhere in this discussion am I advocating for elevated ammonia, I am focusing solely on the endpoint of death and how it relates to belief in whether Seachem Prime has "worked" in a given scenario]

In other words, what would have happened if they did not use Prime in the identical scenario.

We can use published scientific data on ammonia toxicity to gauge what might have happened.

Of course, every species of fish or invert ay have different ammonia tolerability, and pH also plays a strong role.

But let's explore some data.

Here's a 2019 review article published in INDIAN J. MAR. SCI., VOL. 48, NO. 03, MARCH 2019.

NIScPR Online Periodical Repository: Ammonia toxicity and adaptive response in marine fishes – A review

nopr.niscpr.res.in

The authors are at the University of Antwerp, Biology Department (Belgium) and the Central Marine Fisheries Research Institute in India. Thus, it is not a hobby publication, and they have already collected a fair number of previously published experiments to summarize.

Table 2 is what we want to look at.


Table 2 — Comparative toxicity of ammonia to various marine fish

Species TA-N (mgL-1) UIA-N (mgL-1)
4 -Day LC50 Sea bass 40 1.7
4 -Day LC50 Sea bream 57 2.5
4 -Day LC50 Turbot 59 2.6
4 -Day LC50 Cat fish 45 1.6
4 -Day LC50 Rainbow trout 22 0.3-0.6
8 -Day LC50 Sea bass >22.3 >0.9
20 -Day LC50 Sea bream 15.7 0.89
28 -Day LC50 Turbot 38 1
20-Day EC50 Sea bream 15.7 0.89
28-Day EC50 Turbot 17-19 0.50-0.65
55-Day EC50 Turbot 17-21 0.60-0.75
55-Day EC50 Sea bass 22 0.9
LC50 = Lethal concentration for 50% of the population
EC50 = Concentration reducing growth by 50%

Note the important measure: LC50. That is the concentration where 50% of the fish die in the indicated time.

ALL of the data supports the idea that few of these fish (much less than half) would die in 10-20 ppm total ammonia in 2 days. It takes 4 days in more than twice as much ammonia to kill even half of them.

That concentration is a long, long way above what most reefers would use as a trigger point for using Prime. So when fish survive, it may just be the expected result, whether Prime is added or not.

I don't want to make this initial post too long, so we can follow up with additional papers as they arise showing LC50 data for marine fish in seawater.

But I will note here that these results are typical, not an outlier. This paper shows similar results, where more than 1 ppm FREE ammonia is needed to kill half of a batch of silversides in 96 h. That translates to about 25 ppm total ammonia at pH 8.0.

The acute and chronic toxicity of ammonia to marine fish and a mysid - Archives of Environmental Contamination and Toxicology

The acute toxicity (96-hr LC50) of un-ionized ammonia to mysids (Mysidopsis bahia) and larval inland silversides (Menidia beryllina) was influenced by pH and salinity in a species specific manner. With mysids, NH3 was most toxic at pH 7.0 and less toxic at pH 8.0 and 9.0. In contrast, NH3...

link.springer.com

Here is an article concerning clownfish: Their numbers show a little more toxicity (if I remember correctly - I was going to use their limits when doing the in vivo experiment with Prime - but I scrapped the in vivo idea). https://link.springer.com/article/1...-9#:~:text=Ammonia and nitrite can reach,2005).

 

[Randy Holmes-Farley]

Additional paper:

https://onlinelibrary.wiley.com/doi/10.1002/tox.20006

three fish (Sheepshead Minnow, Atlantic Silverside, Summer Flounder) and three inverts all show a 48 h LC50 for free ammonia > 1 ppm.

 

[Randy Holmes-Farley]

Here is an article concerning clownfish: Their numbers show a little more toxicity (if I remember correctly - I was going to use their limits when doing the in vivo experiment with Prime - but I scrapped the in vivo idea). https://link.springer.com/article/10.1007/s10499-015-9965-9#:~:text=Ammonia and nitrite can reach,2005).

Yes, a little more toxic, with the LC50 in 24 h being 1.06 ppm free ammonia, which corresponds to ~25 ppm total ammonia at pH 8.

 

[MnFish1]

Yes, a little more toxic, with the LC50 in 24 h being 1.06 ppm free ammonia, which corresponds to ~25 ppm total ammonia at pH 8.

Here is a quote from the paper (for the rest of the readers that didn't read it): "
False clownfish, Amphiprion ocellaris, is one of the most commercialized fish species in the world, highly produced to supply the aquarium market. The high stocking densities used to maximize fish production can increase ammonia and nitrite to toxic levels. In this study, A. ocellaris juveniles (1.20 ± 0.34 g) were exposed to six concentrations of ammonia ranged from 0.23 to 1.63 mg/L NH3-N and eight concentrations of nitrite (26.3–202.2 mg/L NO2 −-N). The LC50- 24, LC50-48, LC50-72 and LC50-96 h were estimated to be 1.06, 0.83, 0.75 and 0.75 mg/L for NH3-N and 188.3, 151.01, 124.1 and 108.8 mg/L for NO2 −-N. Analysis of gill lesions caused by sublethal concentrations of these nitrogenous compounds showed that both nitrogenous compounds induced tissue lesions such as hyperplasia of epithelium cells, hypertrophy of chloride cells and lamellar lifting to all concentrations tested. However, histopathological alterations were more conspicuous accordingly the increase of ammonia or nitrite in fish exposed to 0.57 mg/L NH3-N or 100 mg/L NO2 −-N. Based on our results, we recommend to avoid concentrations higher than 0.57 mg/L of NH3-N and 25 mg/L of NO2-N in water."

Since the topic is 'just how toxic is ammonia' - it's interesting that pathologic changes were seen at lower levels - and the LC50 at 72 hours was 0.75.

 

[Randy Holmes-Farley]

Since the topic is 'just how toxic is ammonia' - it's interesting that pathologic changes were seen at lower levels - and the LC50 at 72 hours was 0.75.

Yes, I'm certainly not advocating keeping fish in ammonia, just clarifying what I think will surprise people, which is just how much ammonia is needed to kill fish in a day or two (tens of ppm), and how to interpret whether they would have died in a scenario where they are treated with something. .

At pH 8.0, 0.75 ppm free ammonia corresponds to more than 15 ppm total ammonia and it took 3 days to kill half of them.

 

[EeyoreIsMySpiritAnimal]

@Randy Holmes-Farley , how many of the available Ammonia hobby tests actually measure free ammonia? I know API, for example, measures total ammonia.

 

[MnFish1]

Yes, I'm certainly not advocating keeping fish in ammonia, just clarifying what I think will surprise people, which is just how much ammonia is needed to kill fish in a day or two (tens of ppm), and how to interpret whether they would have died in a scenario where they are treated with something. .

At pH 8.0, 0.75 ppm free ammonia corresponds to more than 15 ppm total ammonia and it took 3 days to kill half of them.

Correct we have no disagreement. For example posts that say my pH was 7.9 and my ammonia was 0.25 - and I dosed Prime and everything survived - probably had nothing to do with Prime - and I think its a valuable 'chemistry lesson'. Which is why multiple anecdotal comments that Prime 'works' - can't really be trusted without knowing pH Salinity temp and the margin of error of the test kit.

I think you saw my thread in my freshwater tank - where I had clear (due to my stupidity) - where about 2000 worth of discus were floating belly up in a 200 gallon aquarium. And - after adding the product (not prime) - within an hour they were swimming normally. Other than that product - I cannot explain any other reason (I texted the seller of the fish and he suggested nitrite)

 

[MnFish1]

@Randy Holmes-Farley , how many of the available Ammonia hobby tests actually measure free ammonia? I know API, for example, measures total ammonia.

I will give my answer - the Seachem alert, the seneye, supposedly the Seachem multitest, and probably a couple others. To me the question is not 'what measures free ammonia' its the title of the post which is (paraphrased) how toxic is ammonia really. And PS. EDIT - it is more than the average hobbyist thinks

 

[MnFish1]

I will give my answer - the Seachem alert, the seneye, supposedly the Seachem multitest, and probably a couple others. To me the question is not 'what measures free ammonia' its the title of the post which is (paraphrased) how toxic is ammonia really. And PS. EDIT - it is more than the average hobbyist thinks

BTW - what I mean is - if someone gets an api ammonia of 0.25 its quite unlikely that that is causing a problem - however - if its 0.25 on day one and 0.50 on day 2 that would be a worry

 

[kecked]

Also fish can survive be still be harmed long term. I had a set of clowns that survived a severe ammonia spike over a week that killed everything else. They lived but passed away one after the other in a months time. And they just didn’t act right so I suspect they had some trauma from the situation that eventually got them. My levels were 0.5ppm on an api kit and peaked at 2.5ppm for 24 hours falling back to 0.25ppm where they remained until their death. I tried prime. It didn’t help. Once the nitrogen cycle was hosed it never recovered and I’m rebooting the tank now. Why this happened is a different story not for this thread. That tank was up for 8 years.

 

[Garf]

@Randy Holmes-Farley , how many of the available Ammonia hobby tests actually measure free ammonia? I know API, for example, measures total ammonia.

Total Ammonia Calculator

Aquarium calculator; Estimate the total ammonia concentration given either the free ammonia (NH3) or ionized ammonia (NH4) concentrations.

www.hamzasreef.com

 

[Randy Holmes-Farley]

Total Ammonia Calculator

Aquarium calculator; Estimate the total ammonia concentration given either the free ammonia (NH3) or ionized ammonia (NH4) concentrations.

www.hamzasreef.com

Thanks, Garf

 

[EeyoreIsMySpiritAnimal]

Total Ammonia Calculator

Aquarium calculator; Estimate the total ammonia concentration given either the free ammonia (NH3) or ionized ammonia (NH4) concentrations.

www.hamzasreef.com

Thanks. I guess my point was, if one understands what their ammonia test actually measures, they will be able to make a more informed decision about the level of toxicity. If you don't already know if the test measures total or free ammo, the calculator is useless.

 

[Garf]

If you don't already know if the test measures total or free ammo, the calculator is useless.

As far as I'm aware, they all tell you what form they measure.

 

[Malcontent]

Were the sea bass at least ill-tempered?

 

[Randy Holmes-Farley]

Thanks. I guess my point was, if one understands what their ammonia test actually measures, they will be able to make a more informed decision about the level of toxicity. If you don't already know if the test measures total or free ammo, the calculator is useless.

Unless the kit says it measures free ammonia, it is almost certainly total ammonia. Free ammonia is harder to measure.

 

[EeyoreIsMySpiritAnimal]

Unless the kit says it measures free ammonia, it is almost certainly total ammonia. Free ammonia is harder to measure.

And most new hobbyists probably don't know this. Thank you for clarifying.

 

[ISpeakForTheSeas]

My one study to add into the mix here (this is not a topic I've explored heavily) - 96hr LC50 for young (20-24mm; average full size is 80-100mm) Asian Green Mussels (Perna viridis) was 7.60 mg/L for NH3 and 13.00 mg/L for NH+4:

https://www.jstor.org/stable/24813168

Edit: Just to add, using the Total Ammonia Calculator linked above, under the conditions of the experiment with the mussels (pH range from 8.0-8.3; temp range from 28-30C), the total ammonia would have been ~89.4ppm (~60.6ppm at the lowest possible combination and 133.7ppm at the highest possible combination).

 

[Jmp998]

Your points are valid, however I would raise a complicating issue. I have not read the primary literature carefully, but I would expect there is one significant limitation. While valid, the experiments have only a single variable-artificially elevated ammonia. Therefore these experiments show only that fish can tolerate high ammonia when other parameters are otherwise reasonable.

I would argue that in most 'real world' cases of elevated ammonia, there are probably other less than ideal parameters-the ammonia elevation does not occur in isolation. There may be concurrent increase in CO2/decrease in oxygen/temperature swings etc if the elevated ammonia is due to prolonged shipping for example. It is quite possible that when other parameters are less than ideal, the effective LC50 of ammonia is lower. Therefore it is theoretically possible (although I remain skeptical) that in these real-world situations, ammonia may be toxic at lower levels, and Prime etc is of some benefit, at least in some situations.

I would suggest that the best way to really address this is to perform similar experiments with and without Prime, see if there is a significant difference in survival, and if there is then perform further experiments to see if the effect is really related to 'ammonia detoxification' or some other mechanism. Until it is shown that Prime does not enhance survival, I think the argument can always be made that through some mysterious and marvelous mechanism Prime makes ammonia less toxic and is therefore beneficial.