If you add ammonia and get a reading of no ammonia, no nitrites, but nitrates, then your tank is cycled and you are good to go on fish. Just do a water change to remove some of the nitrates, and all will be good. Ideally you want no ammonia or nitrites and under 20ppm nitrates. Sometimes people find it impossible to get lower than 40ppm nitrates, which is o.k, but shoot for 20ppm or lower if you can.
Emily
