well, in my experience, and from people that I know personally, tetras, especially neons, are very weak in unstable tanks. Before I knew about the whole "cycling" thing (before, i though, buy a tank, and put fish in it... I was wrong!!!) I bought some neons, and they were dead the next morning. Same thing happend with some hi fin black tetras. I do agree with everyone here though to do some research. Use the search tool on here too, it helps me out allot.