Ok, need a bit more information.
First of all, what were the fishes names? Latin names if possible, common names if you can't. If you need ideas, go to
http://www.liveaquaria.com/product/c...=21&pcatid=830 for a possible
ID.
Second, what exactly were your water params? Let's start with pH,
gH, Amm, NitrItes, and NitrAtes. What was the water temperature?
Third, tell us about your tank--water capacity, substrate, decorations, how long it has been operating, etc.
With this information it will be easier to find out what went wrong.