sick tank - help!

Question
I added three new green tiger barbs to my tank and within two weeks they were all dead. They would sit at the bottom corner of the tank and breathe and move their mouths rapidly. I thought that I just had a bad group from the pet store but when I got another set these started showing the same symptoms. I separated them from the rest of my fish who had been fine, but now some of them are starting to show the same symptoms. One of the tiger barbs has lost its color. What could this be and how can I treat it?

Answer
This sounds like ammonia or nitrite poisoning.  How long has the tank been set up?  How many other fish are in there?  Have you cycled the tank.  Please buy a liquid reagent test kit for ammonia, nitrite and nitrate. Test the water.  If ammonia is over .25, nitrite is over .25 or nitrate over 10, please do a 50% water change.  You should also do a 50% water change weekly, weather there is ammonia, nitrite at all.  If you are cycling, you may have to change 50% of the water daily for 6-8 weeks.  If you have more questions, let me know.  Good luck Matt