High No3 Still.

[kiddykat2085]

my no3 is at 100mg/l what can i do
help how long will my fish last like this

 

[fluttermoth]

Nitrate is only really poisonous at higher levels thatn 100ppm; more like 300 or so. However it will cause slow, long term damage at levels over 100..

The way to get it down is through more, larger water changes than you have been doing. Use warm, dechlorinated water and the nitrate will come down.

 

[Rynofasho]

Ya, even 100ppm is fairly high. Like the above poster said, best way to reduce nitrates is a big water change, coupled with a thorough vacuum of the substrate. Be careful you aren't overfeeding, and if you have plants or a planted tank and have space, certain plants like hygros and pennywort are good for sucking up excess nitrates out of the water column.

 

[RadaR]

I'd be more worried as to why it's reached this concentration. It would suggest lots of fish waste and or un-eaten food. Nitrate is often the smoking gun and gets blamed a lot for fish deaths. However, the majority of the time it's not the nitrate that's harming the fish, but the process that has taken place in order to reach the high NO3 concentration i.e what I said earlier about lots of fish waste.
However, this is assuming that your concentration is correct. After all, nitrate test kits are horribly innaccurate....yes even if you shake them well.
As the others have said, perform some water changes. Make sure your filter(s) arent clogged. Maybe check how much stock you have and how much you're feeding.