IMO and IME, there is something completely wrong with the tank as a whole if it is not cycled and there are no ammonia levels at all, but there are nitrite levels. I know I am sure that I havent read your other posts or anything, but unless the tank is very nearly cycled, you would have both small ammonia and a bit higher nitrites. I say this because the nitrates would then be much higher than 10 ppm unless you just did a water change...that make any sense?
I would invest in another test kit just to make sure that yours is not wrong, especially if it is test strips. With that many fish in there, and doing 50% water changes, you should not be nearly done cycling, in my opinion. This is one reason why cycling with fish actually takes longer, because when you have to do constant water changes, just to keep your fish alive, you are also taking out the bacteria's food (ammonia and nitrites), thus slowing things down a bit.
I think everyone is losing the focus of MollyFan's problem here, but I also wanted to chime in because I have noticed, over about four months since I joined, that rbishop is always getting slammed for trying to help you all cycle your tanks and do it in the most humane way possible. I am not trying to make anyone mad, and so please don't get defensive, but there are so many things that can happen negatively to a fish when it is in unhealthy or uncycled water and I just dont see why anyone would so passionately defend the thinking that it is 100% completely fine to do this. I am not saying that it cannot be done, but certainly should be avoided. Just because a fish is acting totally 'normal' and not listless or gasping for air, among the other visual ques that have been pointed out, does not mean that they are not being hurt at all. It would be the same as if one of us was stuck in a room full of smokers, the 'damage' that is being done is not always instant and has long lasting effects. Ammonia, even if it does not kill a fish, can burn its gills and do unreversable damage. You also cannot see or visually inspect a fish's slime coat most often and so how do you know the fish is healthy enough to fish off Ich and other problems when you have to replace fish during a cycle, without quaranteening them 99% of the time, because another one died?
My point is that when someone who is trying to point out how things could have been done better, they should not just be slammed and slammed from every different direction becasue there is a 'loop hole' to get around things. Everything has a consequence and the best situation would be to just cycle a tank without fish since it is now totally possible. Just because it was done in the past, does not mean it is the best method. As far as people who write books, sure most of them are qualified and full of good information, but I would also like to point out that Adolf Hitler wrote a book and I dont think anyone would quote everything he had to say as the best method for anything. I would be leery of any book 'for dummies' since all of those books are meant to written in very plain language so anyone can understand them and I am 100% sure that they do not explore all of the complicated issues behind certain situations dealing with keeping a fish tank. Just be mindful of people like rbishop and a few others, moderators or not, who really are trying to help out, and not create a debate every time he or she writes some advice.