Originally Posted by threnjen
Inadvertently - do you just mean their tolerance outside of some "protective" element?
It seems like it's alllll over the place for all species. So really hard to quantify.
What we really need to find out is - what are the long term effects of short term exposure. In the short term, high nitrites are going to make the fish "suffocate". We know we can protect them with a very low sodium chloride level. But if the nitrite goes away, is everything back to normal? Because we know that in a cycling situation everything is eventually going to be fine.
I see 1 ppm
, 2ppm thrown out as dangerous levels but like you I want to know "why", what is specifically dangerous about these levels.
Basically fish already have a background level of meth in their cells. Every species is different but let's say on average it's less than 10%.
Apparently fish have these reductase cells that reverse the production of meth from nitrite. Small amounts of nitrite the fish can combat and also the longer they are exposed to nitrite the more efficient these cells become. Obviously if this nitrite is too high then the balance is lost and meth takes over the cell.
But seriously, these tests were done on large catfish and salmonoids tench perch and carp.
There has already been discussion on how smaller fish of the same species are less susceptible. And the report on the danio shown miles less susceptibility than these fish. I think size and species that are naturally smaller are less susceptible to begin with.
The fish will and can reduce all levels of meth back to background if nitrite levels are decrease. I also thing O2
saturation is important too but we need to look at that more closely.
Long term effects are those really associated with no oxygen getting to the muscles/organs. I also read that less active a fish is or stressed the less effect the toxicity has on the fish.