Do jack dempseys have a high tolerance to ammonia?

When i test my water i always have high ammonia it been that way for 6 months cuz my damn tank wont cycle yet my jack dempsey is still growin, happy, and has no diseases or effects. Could my tank actually be cycled and its just some product i used to boost my bacteria giving me false readings or something. Should i try puting another fish in just for the hell of it?