Nitrate possibly more harmful than commonly believed

[Sk8r]

A little reading on the nitrate cycle [I was researching something else] turned up some modern thinking in the hobby that, while nitrates are reckoned no big deal for fish, the picture may be more complicated, and exposure to elevated-above-natural nitrate levels over time may be harmful to fish.

Just thought it might be worth tossing into the ring for comment and debate among more expert hobbyists.

How high is high? How successful are FOWLRs with elevated nitrate at fish survival longterm? Has anyone any experience with fish health issues that might be related? [Items affected include, reportedly: liver, immune, respiratory, reproductive systems.] [Liver would relate to ability to excrete toxins; respiratory would impact ability to survive/thrive in oxygen levels in the appropriate tank situation, ime.]

 

[elegance coral]

Do you have a link to the info you're talking about?

It only seems logical to me that if you take an animals that lives in the pristine waters of a coral reef, and keep it in waters more closely resembling those of a mangrove swamp, that health issues would arise. JMHO.

 

[syrinx]

The pendulum will rest somewhere in the center. For a period, nitrates were considered not a issue- then they became a issue when they were blamed for lateral line problems. When the lateral line problems were found not to be caused by nitrates, the science guys came in with their explanations of why nitrates "should not" be a problem to fish. What happens in a lab, rarely translates exactly to a aquarium, due to variables in systems and no controls-so there is prob a middle ground of safety. I have many fish in the 10 to 16 year range-prob 20 or so, and they have been exposed to high nitrates at times-but for the last 5 years or so have been at 40 or less- usually 0.

 

[Sk8r]

I'm finding a number of articles that hint around at it, but all are proprietary to other clubs, reef sites, and reefing magazines, etc, that are not legitimate for me to link to on this site---however, if you google ammonia to nitrite to nitrate, you will find some. The gist seems to be that there are some species of fish more sensitive than others, that wild-caught are more sensitive than those captive-bred for generations [the intolerant perhaps failed to reproduce, and reproductive health is one area alleged to be affected---indicating that people attempting to breed fish should watch that parameter, imho]---and also suggesting that high levels over time could have effects. Fuges suck up nitrate as fertilizer for algae, and the installation of a fuge might have beneficial effects for FOWLRs. As well as providing treats in the form of amphipods. Having never kept a FOWLR I'm no expert in the area, but it is a reasonable thing to me that the addition of green plants to assist with oxygenation [cheato is a fierce oxygen producer] and with nitrate as well as phosphate consumption would be a good thing. I mention it not because I have an axe to grind in the question, but because I ran into it while researching another question, and thought it might be well just to toss it out into the Advanced arena, to let those who are more closely concerned and experienced in this type of tank kick it about.

 

[jackryan]

I would imagine as always in life, anything in excess or not in moderation is bad --- I guess, same here with Nitrates, perhaps?

 

[dogstar74]

I'm not sure if this is a site you're talking about, but I don't believe it's proprietary. This may have some bearing on our discussion. This is in relation to terrestrial animals, and people, but living systems share common physiology for the most part.

http://www.nitrate.com/nitrate3.htm

"Nitrate is a potential human health threat especially to infants, causing the condition known as methemoglobinemia, also called "blue baby syndrome". Read about the impact of Nitrate in water used to make baby formula, on the infant. When Nitrate is taken in by eating food and drinking water, Nitrate is converted in the gut to nitrite, which then combines with hemoglobin to form methemoglobin, thus decreasing the ability of the blood to carry oxygen. Infants are more susceptible to nitrate toxicity than older children or adults. Fatalities are rare, but sub-acute methemoglobinemia can be asymptotic while affecting development, making the condition particularly insidious. Chronic consumption of high levels of nitrate may also cause other health problems, for example some cancers and teratogenic effects; data are inconclusive, but cause for concern (3, 4)."

"High levels of nitrate in livestock feed and drinking water can result in reduced vitality and increased stillbirth, low birth weight, and slow weight gain and even death of the animals affected (6). Chronic nitrate poisoning is correlated with abortions, still births and stunted calves. Abortion is attributed to maternal and fetal methemoglobinemia resulting in fetal anoxia (particularly in the last tri*mester of pregnancy). More recently, unpublished data indicates serum progesterone is reduced in chronic nitrate toxicosis in cattle and, possibly, horses. Chronic nitrate toxicosis causes loss of condition, loss of weight, reduced milk production and weakness. Deficiencies of vitamin A & E and hypothyroidism are reported in cattle and swine. For information on Nitrate Toxicity in Ruminants (Newsletter Animal Disease Diagnostic Lab, Purdue) http://www.addl.purdue.edu/newsletters/2001/winter/nitrate_tox.shtml"

I think that most people think that the ammonia process only works from one direction. Ammonia > Nitrite > Nitrate. This website seems to indicate that within the digestive systems of living organisms, the Nitrate can be converted back to Nitrite, thus causing an increase in Methemoglobin. This reduces available oxygen transport, and increased stress within the organism.

Also Nitrate is an oxidizer. Like a bleach or peroxide solution. So all the harsh side effects of those chemical should translate to Nitrate as well.

Just my .02
Aaron

 

[greenbean36191]

In fish, methemoglobinemia is called brown blood disease. It's a major problem for FW fish, especially in densely stocked production ponds for the same reason outlined above for terrestrial animals. However, the cure in the case of fish is to add salt to the water because the nitrate and chloride ions compete for transport into the blood. All it takes is a ~3:1 ratio of Cl- to NO3- to prevent methemoglobinemia in fish. At least in theory, so long as your nitrate is below 11,600 ppm, methemoglobinemia shouldn't be an issue for any of your marine fish.

I'm not aware of any research that indicates that elevated nitrate is harmful to marine fish either short or long term.

 

[bryan007]

Having FOWLR tanks for many years and hosting innumerable species of fish I can assure you that any major deviation form the animals natural habitat has a negative impact especially when it comes to the quality of water. Saltwater angelfish are notorious for doing poorly in high DOC water to point of death just to name one.

 

[Floyd R Turbo]

This is interesting. I didn't know the connection between high nitrates and chloride ions. It certainly explains a few things. I have 'rescued' several SW FOWLR tanks that had Nitrates as high as 1200ppm, and had fish living in them. I figured that they were OK because they had become slowly acclimated to it over time. The evidence that proved this was when one owner bought a new fish after I told him not to, and it about died in 45 minutes.

I know that Eric Borneman in his 'Mything the Reef' articles points out that Nitrites are not toxic at just about any level to marine fish, but I thought Nitrate was still toxic. Maybe that's just to corals and inverts.

 

[BettaGirl]

I attend a lecture on nitrate, the unknown toxin. Florida university has been doing some work on this, looking at developmental issues with larvae, etc... But the levels they were concerned about where much higher than your typical tank, think 100 mg/l or higher. They are still working on the problem.