Aropwn, it is obvious to all involved you don't test for ammonia and nitrites - the million times more toxic substances than nitrates.
1. If you don't do that, it is impossible for us to help you.
2. If you intend to be a serious hobbyist and keep a serious fish (like the ones you have), you must test your water for all 5 parameters I mentioned or, at the very least, find an LFS that will do it for you. Many LFSs here in the US do it for free. But you will not be a serious and earnest fish-keeper without doing at least these most basic of tests yourself. I buy API master test kit (NH3, NO2, NO3, and pH two ranges) for $24. Lasts years. Thousand of tests each bottle.
3. The ammonia and nitrite tests determine the "cycledness" of your tank. Nothing else! They must be at zero, then your tank is cycled.
4. Gill curl is irreversible. Can be cut back with a scalpel but chances are still against you that it will gorw back fine or even grow back at all.