how bigs the tank and how quickly and how many fish did you add?? The problem with new tanks is there is no bacteria to break down the ammonia so it will go sky high, some fish might make it but if u can u are best off gettin them out of there untill the cycle completes. This is why most people do fishless cycles now because its just too harsh on the poor fish!
Also with fish in or out just do as many water changes as poss, once a day if necessary, if you take the fish out u need to aim for the ammonia to be about 4 or 5 ppm.
hope this helped.
kez