Posting this here as well so more people will see...

Hi all, I have had this goldfish for about two years.  He is the kind that has the bubbly head (sorry, I'm not well-versed in fish).  I have been noticing some changes in him and don't know if he's getting sick.  It almost looks like he has air pockets on some of his scales, and a big air pocket around his eye.  The end of his tail is also turning black, very little though.  It's as if someone drew a black line on the edge of his tail with a marker.  Are these things I should be concerned about?  He's still eating and swimming.  Any input would be appreciated, and I can try to take some pictures if that would help.

What kind of goldfish is it? A picture always help in diagnosing an illness if you can post some.  Black lines, black spots, etc .. are usually a sign of ammonia burn ( very bad water quality) . Have you tested your water recently? I would get a water test kit and do a check for ammonia level, nitrites , and nitrate to see if they are at a normal level.  If any of these levels are very high, do an immediate very large water change at least 60 % - 75 % . The air pockets and they eye problems could be an indication of dropsy (usually caused by bad water quality) developing or some other illness.  What is the size of your aquarium, how often do you change the water, and how often do you feed the goldfish?