Sick Bala Shark

[FisherGirl]

Hello!
My Bala Shark is sick, I have tried calling the local fish stores and PetSmart, but they have not been helpful  
I have noticed that my shark has been gradually loosing his scales.  At first it was a small spot so I thought that he must have rubbed against a rock or something, but it spot continues to get biger and is on both sides of his body.  He now has No sccales from his dorsal fin down to his tail.  He also seems to be having a hard time breathing and he does not move around as much, he stays near the surface. 
I have had him for almost a year and never had a problem before this.  Here are some pictures. The first picture was taken a couple weeks ago, the second picture was taken today. Any information would be greatly appreciated!!
Thanks

 

[TallTree01]

As soon as I saw the title I knew the problem. Questions for you to answer:
Does the shark have at leat 6 other bala sharks with him?
Is the tank 300 gallons or more?
Do the water tests read 0 ammonia, 0 nitrite and 20> nitrate.?
If your answer is no to any of these questions, that's why your shark is sick. If your answer is yes to all 3 questions, it's a problem hat my brain is unable to answer.

 

[FisherGirl]

The levels read fine. He is the only Bala, I know they are schooling fish, I have had him for about a year not sure why he would jest be getting sick now if he is depressed/lonely?  He was always so active and seemed happy.  Could depression really cause this? 

 

[TallTree01]

Have you added anything recently to the tank? New ornaments, plants, rocks etc?

Have you put any chemicals in or around his tank? E.g spraying air freshners around his tank?

 

[FisherGirl]

There has been nothing new added to the tank, however I did do a water change last week. He has been this way before the water change was done, but maybe that wasn't good for him?  I only changed 20% of the water. As for air fresheners I don't use them in them anywhere in the house, as I am sensitive to strong smells myself    I was thinking maybe he did scratch himself on an ornament, and maybe got an infection?? Would that be possible? 

 

[TallTree01]

That would be possible. Are there any sharp or jagged things in the tank?

How bigs the tank?
Are there sharp or jagged things he could scratch himself on?

 

[FisherGirl]

Nothing that I would think would be sharp, the ornaments don't feel sharp to me when I handle them for cleaning, It's a 55 gal.  One of the pet stores said it was a fungus? 

 

[TallTree01]

Fish are much more prone disease when:
A. They are lonely
B. they are stressed by tankmates
C. They are being stunted by small tanks.

All of these are possible possibilities to why your shark has an infection/ fungus/ other injury. All of them are reasons why he's sick. Im not great with balas or mystery illnesses so I can give little help. Hopefully someone more knowledgeable than me can help you out. If he survives, rehome him or get him a 300 gallon and 6 other bala sharks.

 

[FisherGirl]

Thanks for your help and information