Trying to answer a few of your last questions concerning the fish...
I believe zebra danios are very hardy and can survive a lot of "abuse" (toxic level wise) - i am not certain about the plecos.
Either way - toxic ammonia and nitrite cause the fish to be stressed as their body has to deal with the toxins. The longer they are subjected to stress the bigger the chance their immune system wont be able to fend of any bacteria, virii or other pathogens - and then they get sick or die.
Levels of Ammonia 1.5 and Nitrite 0.8 are already very dangerous and if you had more fragile fish they might already be dead. Usually when 0.5 Ammonia and 0.25 nitrite are present things start to get bad real fast.
Please i dont say this to make you feel bad - just stating the facts.
Its also important to note that other tank parameters (pH, temperature, oxygen content etc) also play a role in how problematic those levels are.
There are many signs of fish stress you should watch out for - unusual behaviour, not eating, clamped fins, heavy breathing, listlessness, faded colours and probably many others i cant remember right now.
I believe zebra danios are very hardy and can survive a lot of "abuse" (toxic level wise) - i am not certain about the plecos.
Either way - toxic ammonia and nitrite cause the fish to be stressed as their body has to deal with the toxins. The longer they are subjected to stress the bigger the chance their immune system wont be able to fend of any bacteria, virii or other pathogens - and then they get sick or die.
Levels of Ammonia 1.5 and Nitrite 0.8 are already very dangerous and if you had more fragile fish they might already be dead. Usually when 0.5 Ammonia and 0.25 nitrite are present things start to get bad real fast.
Please i dont say this to make you feel bad - just stating the facts.
Its also important to note that other tank parameters (pH, temperature, oxygen content etc) also play a role in how problematic those levels are.
There are many signs of fish stress you should watch out for - unusual behaviour, not eating, clamped fins, heavy breathing, listlessness, faded colours and probably many others i cant remember right now.


