sounds to me like a problem
Can you give us some tank stats? When you say you just set up your tank, did you cycle it at all?
If the answer is 'no' or 'whats cycling?' then have a look here -
[URL="http
/www.fishforums.net/index.php?showtopic=277264"]http
/www.fishforums.net/index.php?showtopic=277264[/URL]
I'm guessing you just filled up the tank, left it for a while then added fish right? If so then you have whats called 'new tank syndrome' basically you need to prepare the tank and filter so they can support the fish you add...its all explained in the link above.
In the mean time, you can do a 50% water change, with water conditioner, leave it an hour, then do another 50% change.
You really need to get yourself a liquid based test kit, as they're pretty much essential to new fish-keepers
HTH