Not entirely true. You can also acquire what is known as "Old Tank Syndrome". However, if you are OC about your water changes and the amount fed, it will help prevent that. Failing to maintain your water properly is just as bad as having an un-cycled tank and almost backs you up to re-starting a cycle.
Nitrate is good. Have you added an air pump of some fashion? Air pumps will help the water to off-gas better allowing for better oxygen exchange as it also creates a larger water surface area
Lol "throw". I don't know your stocklist( did you list this earlier?), but maybe move two or three of your hardiest fish. What size is your tank? Good news is if you overdose a little on the amquel at water changes, it will def. help the fish.