# Affects of Nitrate on fish



## Tetanus

Hi

I have heard many things about nitrate and fish but they mostly seem to conflict with each other. Some people say that it will do damage to fish and others are saying that it doesn't do anything to them. I have been keeping a fish only system for a few years now and have always had problems with nitrate an have had fish die for no reason at all as far as i can see. I have always thought that this was dew to nitrate but recently i have been told otherwise by someone i work with who breeds clownfish. Can some one please clear this up for me and give me a definitive answer on the matter for tropical and marine. All help on the matter is appreciated.


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## fishfreaks

ive heard that theyre very dangerous at high levels


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## Osiris

on just marine fish i believe up to 30ppm is ok, but shouldnt be that diffcult to keep it way lower then that. As lower the better, now if u have corals and stuff in it, u want 0 accross the board.


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## Sly Guy

http://www.advancedaquarist.com/issues/august2003/chem.htm

just something to look at 0 is the best of course but up to 40 in freswater and saltwater is okay but if it is that high i would be doing something


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## wrasser

fish do have a higher tolarence for nitrates and nitrites, remember it is gradual that they raise. so they are kind a acclimatedinto it. as for clown fish, they are part of the damsel family, so theu are quite hardy.


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## redpaulhus

Unfortunately, this is one area where the hard science (as opposed to unsubstantiated speculation) has been focused more on commercial mariculture rather than the hobby.

It does seem that truly elevated nitrate levels will affect a fishes immunosupressive system (see http://www.atlantech.ca/articles/Water Quality.PDF etc) or fecundity (see here http://www.waterlife.co.uk/seaquariums/coralfish2.htm )
But much of that assumes much higher than hobbyist nitrate values - finfish culture generally leads to extremely high nitrates.

However, keep in mind that the nitrate values along most of the worlds reefs fall in the 0.000002 ppm or lower range -- several orders of magnatude lower than even the lowest detection threshold on common hobbiest tests. A typical 10 ppm reading in a home aquarium equals 5,000,000 times more nitrate than the fish would experience in the wild. Its pretty safe to assume that even at this level the fishes immune system is being affected, allowing an oppurtunity for other stressors to lead to illness or death.

Over the last 15+ years I've certainly seen fewer cases of HLLE in tanks with lower nitrate - in fact, the occurance of HLLE has dropped off in a pretty consistant rate with the development of NNR based aquaria. Back in the 80's HLLE was as common as freshwater ich, now its a rare occurance (at least as far as I've seen as a consultant, aquarium club speaker, LFS employee and aquarium service provider).

Lastly - nitrate is often used as a 'flag' for non-detectable elements such as dissolved organics, which are generally not tested by hobbyist level kits. Systems with insufficient nutrient export mechanisms tend to exibit not only high nitrate levels but also excessive levels of compunds such as long chain proteins, amino acids, pheromones, etc that can certainly impact fish health.

(which is why ORP is such a useful indicator)


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## redpaulhus

more info:
http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=560


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## wrasser

do the protien skimmer assit in the non-detectable elements? i know they help in dissolved organics, do they assit in more than that?


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## redpaulhus

Certainly


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## Thunderkiss

Dropsy, pop-eye, fin and tail rot, head and lateral line erosion ... all have been claimed to be a reult of excessive nitrates.

And realisticly, look at it this way: test your nearest large body of water for nitrates and take note.

They don't have to deal with it nature, they shouldn't if at all possible in an aquarium.


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