please help

[hende]

i had bought two baby oscars they are about 2 inches long one died today and the other looks as if he is gasping for air the one that dieds moth was fully open when i found him they have no wounds on them they are in a 55 gallon tank with a heater power head bubble wond and a 40/60 hand on back filter tank is well cycled it had two other fish in it for 7 monthe that never had any problems at all my water test showed as fallows pH 7.0 to 7.2 my ammonia is at 0ppm my nitrite is at 0ppm and my nitrate is at about 10ppm to 20ppm any help would be grate i have had them since saturday

[carpediem]

What is the temperature? Issues with chlorine? Have you added anything to the tank since you put the Oscars in i.e. cage furniture, additives etc?

Gasping tells me that the fish is in some kind of respiratory distress. This could be caused by a lot of different things. If the temperature is where it should be and there are no other obvious causes, I would just do a 50% water change, keeping the temperature as stable as possible and using a quality water conditioner. I would then follow it up with a few more water changes over the next week or so.

[liv2padl]

is your water chemistry quite different from the place where you bought them? how did you acclimate these fish to your water.