Maximum Safe Nitrate levels for fish?

[wh33t]

Hello all,

I've just got my Nitrate test kit and I'm curious as to see what kind of readings I should want to get?

I've got 8 gold fish so it would be great to know the maximum safe level for them but I would love to be able to look up that kind of information as well, is there any way to do that?

[keith_r]

you'll probably hear different opinions... i would be worried if they were above 200

[rfeiller]

i find mine do better at 100 then 200. if you have sufficient grow beds it shouldn't hit 200.

[urbanfarmer]

For catfish to die after 4 days it takes 6,200 mg/L or 6,200 PPM Nitrate. I am still looking for goldfish, but it looks like no one cares what level of nitrate is unsafe for goldfish. This could be because there's no economical benefit to be gained from researching it or the nitrate required is too high (or non at all) that affect the fish. I will post if I find anything closer. For Tilapia the level of nitrate would be even higher than that (basically it can be said it's non-toxic to Tilapia).

Evaluation of the short-term toxicity of nitrogenous compounds to channel catfish, Ictalurus punctatus
aDepartment of Civil Engineering, University of California at Davis, Davis, Calif. 95616 U.S.A.

Abstract
The acute toxicity of un-ionized ammonia, nitrite, and nitrate to 50–76-mm fingerling channel catfish (Ictalurus punctatus) was investigated using a static bioassay system at 22, 26 and 30°C. The 96-h LC50 values at 30°C for un-ionized ammonia, nitrite, and nitrate were 3.8, 44, and 6 200 mg/l.

[urbanfarmer]

This study was interesting to me because it actually contradicts what most online fish folks state, that nitrate levels cause a decrease in fish growth. Nitrate levels do not affect thyroid function, at least in these fish species.

Uptake and distribution of radioiodine, and the effect of ambient nitrate, in some fish species.
Comp Biochem Physiol A Comp Physiol. 1985;80(3):337-42.

[urbanfarmer]

I have several books on aquaculture that clearly state nitrate is non-toxic to fish in general. I know that may be too vague for your needs, but if anyone can show some evidence to the contrary I would (as usual) absolutely love to read it. I look through journals with these kinds of keywords, and it's really hard to find much of anything on the topic: nitrate toxicity LC50 Carassius auratus goldfish

I used several combinations of those terms to try to pull up anything stating nitrate is or is not toxic or of it is at what level... I can't find much.

[rfeiller]

The stunting is caused by the concentration of hormonal secretion of the fish. There are several factors that happening. In a closed system. All aquaponics is only concerned with nitrates. There are fish such as catfish that can exist in a high concentration of sewage. A number of tilapia are from a dead end water system in Africa called the rift river valley system an they have adapted to extreme conditions. Not so for many fish species.
Along with a higher concentration of nitrates is a higher concentration of pathogens and parasites.

[urbanfarmer]

The stunting is caused by the concentration of hormonal secretion of the fish. There are several factors that happening. In a closed system. All aquaponics is only concerned with nitrates. There are fish such as catfish that can exist in a high concentration of sewage. A number of tilapia are from a dead end water system in Africa called the rift river valley system an they have adapted to extreme conditions. Not so for many fish species.
Along with a higher concentration of nitrates is a higher concentration of pathogens and parasites.

Well, aside from the toxins, there are many factors that can stunt fish growth including temperature. However, nitrate, from my experience and research, is not one of them.

As far as the hormonal secretion stunting growth, sure it exists in some fish (I want to say it's rare). I have had to specifically search for fish that do this, and I can't even remember the species, but needless to say I don't think goldfish, tilapia, or catfish are among those that do. There's a lot of folklore and BS out there on the topic, but the sience doesn't back it up... and, unfortunately, a lot of us have read that junk and taken it as gospel.

[badflash]

Goldfish are carp. I don't think you can get to a toxic level unless you add miracle grow. Keep the particulates and nitrites and ammonia under control and you should be good, but don't stick with goldies. Move up to koi or catfish once you've figured out how to handle your water.

[keith_r]

The main toxic action of nitrate on aquatic animals is
due to the conversion of oxygen-carrying pigments (e.g.,
hemoglobin, hemocyanin) to forms that are incapable of
carrying oxygen (e.g., methemoglobin) (Grabda et al.,
1974; Conrad, 1990; Jensen, 1996; Scott and Crunkilton,
2000; Cheng and Chen, 2002). Nevertheless, owing to
the low branchial permeability to nitrate, the NO

3 uptake
in aquatic animals seems to be more limited than
the uptake of NHþ
4 and NO

2 , contributing to the relatively
low toxicity of nitrate (Russo, 1985; Meade and
Watts, 1995; Jensen, 1996; Stormer et al., 1996; Cheng
and Chen, 2002; Alonso and Camargo, 2003).

from
http://www.waterboards.ca.gov/water_iss ... ef2426.pdf

there's a newer study out on nitrate toxicity in fish, but i ain't shellin out 41 bucks