SICK PUFFER... please help

[future]

my puffer doesnt look good and i dont know if he"ll make it threw the night.... hes on the bottom of my tank breathing heavily it looks like, he color is all dissorted and doesnt look healthy at all.. Tonite when i feed my fish, he did have some food but then laid down on the bottom of my tank.,.. any advice would help

 

[TCTFish]

Test the water for ammonia, nitrite, nitrate and pH ASAP. Please give us the results. It would be helpful if you can answer the following questions...

How long has the tank been up and running with fish in it?

How big is the tank?

What else lives in the tank?

What are you feeding and how much and how often?

How much water do you cahnge and how often?

What type of filter do you have?

Is this a tank with live rock?

Is the puffer the newest addition?