Does high Nitrates hurt fish?

[JMLewis]

My tank just got done cycling. Ammonia and nitrites are both at zero after about 9 weeks of fishless cycling using pure ammonia. (Felt like forever) My nitrates are pretty high so I did 2 x 40g water changes over the last 2 days and it brought em down a bit but still pretty high.

I have fish ready to go in from quarentine and I'm pretty sure the nitrates won't hurt em but I figured I'd get some other opinions first.

The tank was started 100% sterile using only dry dead rock and dry sand. The funny thing is its been so long since I've actually cycled a tank without using live rock that I don't really remember the deal with nitrates and fish.

 

[Flame_Angel]

What are your nitrate levels at right now? What you consider high may not be what someone else considers high.

 

[m2434]

Nitrate is not directly toxic to fish until you get up into the hundreds or even thousands of ppm. It also isn't directly toxic to inverts, including corals. However, indirectly, there may be negative effects at much lower levels, but that is tougher to gauge, as there are a lot of factors involved. So, I agree we need more info.

 

[wooden_reefer]

I think high nitrate is not directly harmful to fish, but the reason for high nitrate is generally too uniform high oxygenation within the filter medium.

Too uniformly high oxygenation might also disallow other microbes that have other beneficial functions, may be outside the N-cycle.