Ghost of an Angel fish

Question
Hi, there.
I have a 22 gallon tank that has been no problem at all for the last year and a half.  It's freshwater, and we own one angel fish, a huge goldfish, an algae eater, a rosy barb and a gold danio (not a giant).  I change the water regularly and sometimes add aquarium salt to fend off any bacteria.  I always add ACT drops and Aquari-Sol to balance the water better and avoid ick.  Obviously, I also add the needed amount of Chlorine removal drops.

Recently, our angel fish has been floating all around the tank like a ghost.  She just turns in circles and even floats upside down and sideways.  Last night was the first time she started doing this and this morning she didn't have any interest in food.  Is there a lack of oxygen?  Is our fish food making her irregular?  We just can't seem to figure it out.  Please let me know if you have any way to resolve this.  We are running out of ideas and hate to see her this way.  

The odd thing is that none of the other fish seem to be feeling any differently.  The goldfish stayed near the top for fifteen minutes and went right back to his routine.  The other fish are acting as usual.  

Please let me know if there is anything I'm overlooking.  

Thanks for being available for questions. It really means a lot to me and my husband.  Have a great rest of the day.  Thanks again so much for your help.

Answer
Hi Kristen;

It doesn't sound good. You might try increasing the oxygen level with an airstone hooked to an air pump. It certainly can't hurt. If he has a gill infection it will help him absorb oxygen better. Look for parasites and/or fungus on the gills. Try to see inside the gill plates where the reddish gills actually are. Fungus remedies and parasite remedies could help him or at least prevent infection to the other fish if this is the problem.

You might have the water tested to be sure everything is okay there. The local fish store can test the pH, ammonia and nitrite. If there is nothing abnormal about the water he may have an internal problem. The only internal problem that is treatable is bacterial infection. "Maracyn 2" and "Kanacyn" are two antibiotics that get inside the fish to treat infection. Once they start acting like he is, I'm afraid the chance of recovery isn't good. Wish I had better news.......

Followups welcome

At Your Service;
Chris Robbins