Nitrites and nitrate toxicity

[Fiish]

Some time ago I read in various places about the low or no toxicity of these elements (nitrite and nitrate), so I wanted to know if we can determine the real degree of damage that these elements cause directly to the fish in the short and long term . There is a lot of discussion about the acclimatization of the fish by dripping, on the subject of the lethal ammonia inside the transport bags, this supposes a real damage for the fish in the long term that will end up taking its life since its internal organs have been affected but what about nitrite and nitrate?
I saw a user comment that his fish handle 160ppm nitrates with no problem, and I can only think that there is no way I could keep delicate fish like angelfish, butterflies or clownfish with a level like that, unless you have softer fish like damsels, and in any case it would not seem correct to me.
In any case, beyond stress and increased susceptibility to disease, what is the short and long term harm of maintaining high nitrate levels? Is there internal damage to the fish? How fast can a bacterial disease develop from poor water quality?

 

[griss]

@leebca is probably the best person to answer this.

That said, I'm more of a coral person than a fish person, my understanding is that nitrates are not very toxic to fish. The reason we try to control nitrates is to limit the amount of problem algae in our tanks.

 

[Fiish]

Last week I was at my son's pediatrician's office who has a 50 gallon tank there, he asked me to make some adjustments to his tank and when looking at parameters I observed +160 ppm nitrates, his fish seemed fine although a rather faded blue tang, however it's a 6 year old fish in that tank, besides that there is only a couple of ocellaris clownfish, to be honest I have never seen such a high level of nitrates and obviously I'm sure they were still much higher, he also told me that there has not been a water change in more than 7 months and there is a very marked overfeeding.

 

[Fiish]

Personally in my qt tanks I sometimes find my fish get a bit lethargic and eat less when nitrates are above 40ppm, so at levels as high as +160ppm I can't imagine keeping more delicate fish like butterflyfish or angelfish without it these will show signs of diseases in the medium or long term and a paler coloration.

 

[Timfish]

Speaking just generally, I haven't dug into the research on Nitrate's effect fish or inverts like shrimp and crabs (it does have serious negative effects for corals). Nitrate may have low toxicity for many fish species both short term and long term. But with fish there's still the question of species specific responses so accepting fish in one system appear to be fine might not translate to more delicate species in another system. There is still the question of what's best for a system overall. A marine system is a lot more than a few fish and microbial species even if it doesn't have any "corals" per se, so what is happening with all the other organisms that make up a marine ecosystem. Additionally, just because fish can tolerate high Nitrate levels there's still other types of pollutants that collect in systems and individual fish species tolerance doesn't justify ignoring the maintenance that is needed to keep a marine system healthy.

 

[Jposch]

Generally speaking, nitrate is not a big issue if the fiah are conditioned to it. A friend told me about a customer's Eel tank that was in excess of 1,200ppm no3. Very rough test diluting the sample. Established inhabitants were fine, but any new additions died almost immediately.

 

[Fiish]

Speaking of the system that I'm giving as an example, I could see that it had too much debris in the substrate (gravel for freshwater tanks), there was so much debris that it was sticking out of the gravel, there were also cyanobacteria and a lousy water circulation with only a wave generator covered in "thick slimy" organic matter, proof of gross overfeeding, so the blue tang was very pale, far from the beautiful bright blue they have. I'm sure any new fish added will die, but that won't be the case, I'm going to try to reset the system and slowly bring it back to optimal levels, do a 20 gallon water change and siphon without positive results, I'm sure several more water changes will be needed, this tank doesn't have a sump.
I believe that fairly high nitrates automatically translate to poor water quality to which fish can slowly get used to, however it's not correct, poor water quality leads to bacterial diseases in the short or medium term depending on the individual maintan specifications of each fish, a damselfish can take longer to get sick than a clownfish IMO.

 

[leebca]

Some time ago I read in various places about the low or no toxicity of these elements (nitrite and nitrate), so I wanted to know if we can determine the real degree of damage that these elements cause directly to the fish in the short and long term . There is a lot of discussion about the acclimatization of the fish by dripping, on the subject of the lethal ammonia inside the transport bags, this supposes a real damage for the fish in the long term that will end up taking its life since its internal organs have been affected but what about nitrite and nitrate?
I saw a user comment that his fish handle 160ppm nitrates with no problem, and I can only think that there is no way I could keep delicate fish like angelfish, butterflies or clownfish with a level like that, unless you have softer fish like damsels, and in any case it would not seem correct to me.
In any case, beyond stress and increased susceptibility to disease, what is the short and long term harm of maintaining high nitrate levels? Is there internal damage to the fish? How fast can a bacterial disease develop from poor water quality?

Your post covers 'a lot of ground.' Many issues and questions. The primary point posed is nitrite and nitrate.

Bottom line -- it depends on the fish.

We get most of our information from work done by public and private aquariums. For the most part, the Aquaculture industry doesn't care so much about nitrates. So, there isn't as many published technical papers regarding nitrates. The Aquaculture industry does have some concerns about nitrite levels. But nitrite levels are more toxic to freshwater fish than saltwater fish. Hobbyists that have had freshwater fish may recommend 0 ppm levels for nitrites in saltwater aquaria. So, the information gets mixed up.

However there are published papers such as Nitrite Toxicity. . . Nitrites are problematic to marine fishes (and corals in reef tanks) at high levels. Not so much a problem for marine fish if in low levels. The effects of nitrites can be observed by gill lesions. Thus when an ornamental marine fish is likely to die, a necropsy examination of the gill can demonstrate if nitrites were a contributing cause. While the fish is living, a gill clipping can be taken and microscopely observed for signs of nitrite damage.

'Speaking' in generalities, a continuous nitrite level above 3 ppm may adversely affect our ornamental marine fishes. But it depends on the species. If the marine tank is well oxygenated, nitrites should move to nitrates very quickly by the Nitrosomonas bacteria. A good article on this is Nitrite and the Reef Aquarium. It's worth taking some time to read.

Regarding nitrates. . .Most marine fishes are not adversely affected in concentrations below 300ppm. A fish-only aquarium can have a relatively high (300 to 500ppm) nitrate level without observing problems, or seeing post-mortem exam issues. But high nitrates usually create algae so long as phosphates are available, too. The regular water change schedule will limit nitrate buildup in such levels.

When nitrites and/or nitrates show up in higher than desirable concentrations, the hobbyist needs to evaluate the efficacy of the bio filter and the water change quantity and schedule.

 

[Fiish]

Your post covers 'a lot of ground.' Many issues and questions. The primary point posed is nitrite and nitrate.

Bottom line -- it depends on the fish.

We get most of our information from work done by public and private aquariums. For the most part, the Aquaculture industry doesn't care so much about nitrates. So, there isn't as many published technical papers regarding nitrates. The Aquaculture industry does have some concerns about nitrite levels. But nitrite levels are more toxic to freshwater fish than saltwater fish. Hobbyists that have had freshwater fish may recommend 0 ppm levels for nitrites in saltwater aquaria. So, the information gets mixed up.

However there are published papers such as Nitrite Toxicity. . . Nitrites are problematic to marine fishes (and corals in reef tanks) at high levels. Not so much a problem for marine fish if in low levels. The effects of nitrites can be observed by gill lesions. Thus when an ornamental marine fish is likely to die, a necropsy examination of the gill can demonstrate if nitrites were a contributing cause. While the fish is living, a gill clipping can be taken and microscopely observed for signs of nitrite damage.

'Speaking' in generalities, a continuous nitrite level above 3 ppm may adversely affect our ornamental marine fishes. But it depends on the species. If the marine tank is well oxygenated, nitrites should move to nitrates very quickly by the Nitrosomonas bacteria. A good article on this is Nitrite and the Reef Aquarium. It's worth taking some time to read.

Regarding nitrates. . .Most marine fishes are not adversely affected in concentrations below 300ppm. A fish-only aquarium can have a relatively high (300 to 500ppm) nitrate level without observing problems, or seeing post-mortem exam issues. But high nitrates usually create algae so long as phosphates are available, too. The regular water change schedule will limit nitrate buildup in such levels.

When nitrites and/or nitrates show up in higher than desirable concentrations, the hobbyist needs to evaluate the efficacy of the bio filter and the water change quantity and schedule.

That's a pretty comprehensive answer, thank you very much for the articles you added to the post, so I'm going to read them carefully. What is your opinion that high nitrate levels are linked to bacterial or parasitic diseases in some way?

 

[leebca]

When there are high nitrites and/or high nitrates, there is additional stress put on the fish. If there are no other stressors (e.g., fish fed according to the download then following, the Fish Nutrition document, tank size is appropriate, tankmates are appropriate (no aggressive behavior), water quality, build up of detritus) the fish can handle a temporary high-end concentration. But if other stressors exist, then the fish is compromised and may be more susceptible to infections and parasites.

 

[Fiish]

Thank you for your help