Are you using test kits? If not, invest in API liquid test kit. Avoid test strips as these are grossly inaccurate. You will need to determine your ammonia, nitrites and nitrates. Did you cycle the tank?
i dont know how or how long to the last time i keep fish was when i was 15 and my mom did everything just loved haveing thing i am 20 now so need to learn
also is that drift wood in your tank if it is and you havent soaked it in boiling water before you put in it will leak tanins (sp) into your tank it wont hurt your fish i dont think.