I.D. this fish and possible illness

[AR_Clint]

I just swapped my 30 gallon for my friends 55. I wanted to upsize and he wanted to downsize. The only condition was that I take a certain fish with the tank. He wasn't sure what it was. I was thinking, "Well, I am pretty new to the hobby, but I've read quite a few books about different popular species so I should know what it is when I see it." Wrong. I really have no idea. I've never seen a picture of it before in any of the books I've read.
I'm sure someone will be able to help me out here within a few minutes as far as the I.D.

Also, it looks pretty unhealthy. Its eyes are a tiny bit clowdy and all the fins look fringed and rotting. Hopefully there is something I can do.

http://i13.photobucket.com/albums/a268/AR_Clint/temporary002.jpg
http://i13.photobucket.com/albums/a268/AR_Clint/temporary004.jpg

Thanks guys,
Clint

[Ephraim]

mono argentis

[Sk8r]

It's a brackish water fish, not wholly a marine fish, though it can live in salt water: mono is correct.

Google it and its living conditions. You may be able to trade it [in good health]. It looks as if it's been scraped on rocks. Doesn't look like a disease, just an injury. Watch about infection, films on body, and be careful to acclimate it very, very, very carefully to the same salinity it's in NOW, never mind what it should be. Then you can start adjusting its salinity to what it ought to be.

[AR_Clint]

Perfect. Thanks for the info. You are right about the scraping against rock. However, that doesn't explain the ends of his fins looking faded and disolved, does it?