Nitrate Poisoning

[guppymonkey]

I work at a pet store and my boss is trying to say that there is no need to test for nitrates since they aren't toxic! I am trying to find a good explanation for why nitrates are necessary to test for and how they damage fish. She won't believe me when I try to explain. Does anyone know a good book or website that can explain it so I can show her in writing that I am right? She does water changes but won't admit that nitrates can be toxic at high levels.

 

[dthoffsett]

Can't remember where I found this, but I hope it helps.

If nitrates are not removed by pretty consistent partial water changes, they accumulate. At a certain point they build up in the fish's blood and block the ability of the hemoglobin to carry oxygen to the fish's cells. The fish slow down, may rest on the bottom, sometimes discolor and quietly suffocate, if a disease doesn't attack their crippled immune system first.

 

[Tokis-Phoenix]

Nitrates are only harmful to most fish (i say "most" because some fish are very fragile/sensitive to these things) above 40. Some fish have been known to tolerate very high levels of nitrates though, over 100...Water quality issues are often the cause of many fish deseases encountered in the aquarium, since stress can effect a fishs ability to fight off desease- high nitrates can make fish stressed, or make them difficult to acclimatise properly to a tank.
The other reason why you should test for nitrates is for the health of your tank- a tank with water quality issues may not show any nitrates in the tests, since nitrates are an end product of a healthy ecosystem (unless your tank is course very planted, then 0 nitrates may mean nothing is wrong at all since plants take up nitrates), a complete lack of them could indicate your tank is mini-cycling or somthing etc.