For the moment do a 50% water change to bring the no2 levels down. Have u cycled this tank? If not do the water change and get rid of the fish tomorrow. Because this will be a losing battle for u. What do u use for bio? I also always recommend using Seachem purigen in the system. It will help control spikes once the tank is cycled.
Can you please provide a full run down of your tank...All current tank parameters, what is in there, what equiptment, what live stock, how long has it been running...
We really need more info to be able to help you better...