Help Please! Paroon Shark Lost color?

[Dallasgwilson]

Hi,
So i got home from work today to find only my Paroon Shark affected by something. Currently, he cannot see anything and his black colour has faded to almost a silver colour. I have checked my water and conditions and they are ok, the other Iridescent sharks within the tank are completely fine, and he is the only one showing this. I am wondering if this is some sort of disease or if he just overly freaked out yesterday when i was doing water changes and hurt himself this badly.
Please let me know
http://m.imgur.com/vefo33x,gqTBKml,xREZL39

[Dallasgwilson]

He is almost the same color as my Albino Iridescent, but he is all black usually. I am just very worried since currently he cannot see anything, and is bumping into everything hurting his nose area which is now red.

[Dallasgwilson]

Could this be Columnaris? I treated the aquarium with salt, it just seems weird that after one day something would pop up this severe.
Thanks

[Viktor Jarikov]

Could he have hit something pretty bad? It sounds like a concussion which is not rare with these fish.

Does it feed?

[Dallasgwilson]

Unfortunately, he died this morning. I bathed him in meth blue last night and the other fish since my irid sharks were showing the same symptoms, it seems like it was a strain of columnaris. Very unfortunate since this was my favorite fish and had him since he was a fry. The other fish in the tank seem to be doing better now. Hopefully it continues to be this way since, he was dead in less than 24 hours.

[Viktor Jarikov]

What is the basis for the diagnosis?

http://en.wikipedia.org/wiki/Columnaris states:

Symptoms

An infection will usually first manifest in fish by causing frayed and ragged fins. This is followed by the appearance of ulcerations on the skin, and subsequent epidermal loss, identifiable as white or cloudy, fungus-like patches – particularly on the gill filaments. Mucus often also accumulates on the gills, head and dorsal regions. Gills will change colour, either becoming light or dark brown, and may also manifest necrosis. Fish will breathe rapidly and laboriously as a sign of gill damage. Anorexia and lethargy are common, as are mortalities, especially in young fish.