toxic limits

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fishymctasty

Aquarium Advice Apprentice
Joined
Sep 2, 2008
Messages
20
hey just a question out of curiosity,

what are the toxic levels of nitrite and ammonia? At what levels do they become detrimental to the fish?


thanks in advance ^^
 
Anything above .5ppm generally calls for a 50% water change (that's the standard recommendation here). Deadly levels are different for each fish I would think as some are more sensitive than others.

0 is best and generally what you'll find in a cycled tank... up to .25ppm is 'okay' in my opinion- as in a cycled tank a .25ppm spike will go back down pretty quickly.

Also some tap water contains chloramine which registers as ammonia on test kits- so while most dechlorinators will register that chloramine inert to the fish it'll still show up upon testing- so sometimes .25ppm ammonia is really only .1 free ammonia and the rest 'locked up' ammonia from tap water... makes sense?

I probably over-answered your question huh... :)
 
nope didn't over answer at all :)

was that .5 for nitrite or ammonia?

i was under the impression that nitrite is "less" deadly than ammonia.
 
Both. :) NitrAtes on the other hand are safe up to about 40ppm (although some like to keep them below 20).
 
NH3: Lethal at >1.00 mg/l. Sublethal/internal damage at >.05mg/l.
NO2: Lethal at LC50 <1.00 mg/l. Should remain undetectable for the most part, but varies widely depending on specie.

Courtesy of Noga :)
 
NH3: Lethal at >1.00 mg/l. Sublethal/internal damage at >.05mg/l.
NO2: Lethal at LC50 <1.00 mg/l. Should remain undetectable for the most part, but varies widely depending on specie.

Courtesy of Noga :)

so by that logic no2 (nitrite) is more toxic than ammonia?
 
nitrite cause trouble with fish getting oxygen and "brown blood disease", aquarium salt is known to help fish cope with higher nitrites.

these lethal limits are not set in stone, and I have not researched enough to know exactly, but certainly every fish has its own limits.

The only experience I have to add, is when i cycled my 10g with goldfish(yes a newb) as soon as nitrites showed up on the test kit 1 goldfish was struggling and did not make it more than 1 week even with daily PWC's
 
No, NH3 is far more toxic. LC50 stands for the dosage or concentration of a particular chemical resulting in a 50% loss of tested animals within a specific time-frame. NO2 deprives tissue of receiving adequate oxygen into the bloodstream. The term "Brown Blood Disease" is associated with the 25%+ concentrated NO2 tinging the blood a tan-brown coloration and a tan gills. NO2 loses its toxicity to Chloride (Cl-) by inhibiting the gills to absorb NO2. NH3 at >1.00mg/l clinically shows death within days (weeks time) and sublethal standards heightens overall stress factors within the body, thus breaking down the internal structures that allows the animal to function...so to speak. This is often the case with "New Tank Syndrome" (NTS) when by the time NO2 has become active and beginning to spike, NH3 has already peaked in causing chronic NH3 poisoning and overall body/internal organ failure.
 
No, NH3 is far more toxic. LC50 stands for the dosage or concentration of a particular chemical resulting in a 50% loss of tested animals within a specific time-frame. NO2 deprives tissue of receiving adequate oxygen into the bloodstream. The term "Brown Blood Disease" is associated with the 25%+ concentrated NO2 tinging the blood a tan-brown coloration and a tan gills. NO2 loses its toxicity to Chloride (Cl-) by inhibiting the gills to absorb NO2. NH3 at >1.00mg/l clinically shows death within days (weeks time) and sublethal standards heightens overall stress factors within the body, thus breaking down the internal structures that allows the animal to function...so to speak. This is often the case with "New Tank Syndrome" (NTS) when by the time NO2 has become active and beginning to spike, NH3 has already peaked in causing chronic NH3 poisoning and overall body/internal organ failure.

I find this very interesting. Do you know of any articles that explain this further, and also goes into depth about nitrite poisoning?

thank you all for the info
 
I'd just purchase one of these instead, well worth the money: Edward Noga (Fish Disease), Dieter Untergasser (Handbook of Fish Diseases), and Michael Stoskopf (Fish Medicine).
 
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