Without adding a purposeful bacteria culture?
Even so, I performed 20% water changes every three days or so for the first two weeks and we fed the fish sparingly. With each water change I’m siphoning out the water (and trying to clean gravel,) and then adding fresh tap water to which I’ve added a conditioner (to remove chlorine, give neutral ph, etc.) and the new water is temperature matched (around 67-68 degrees.) The tank is kept at room temperature and the thermometer strip always shows it’s between 66-68 degrees, so presumably it’s right at 67.