Fog, or Atmospheric Perspective

I just bought two new fish the other day, two days ago exactly...and one of them already died.
My betta seems happier than ever, swimming around the cubical of a tank like he owns the place (which he does) and my goldfish right across the table from him, is floating at the top, with what almost looks like a dusty coating on his scales. I can't believe Donatello didn't survive. I should go back to the pet store to see if I could get my fifteen dollars back; those bastards.
Okay, sorry for the profanity...but tonight hasn't exactly been my night.
'nough said for now...I can't write in this [New York] state of mind.