Yellow Tang Sick :(

[victorcan]

Not sure what it is, my guess would be Lateral Line , but not positive.. His Dorsal fin is deteriorating and he seems really skinny even though he feeds 2x p/day.
I noticed this began about a year ago and removed my carbon from the sump.. He never improved but it didn't worsen, now he's looking really malnourished.. Not sure iff its related but again he never recovered from the initial sickness. He's about 5 years old, so he's had a good run but..... Is there anything I can do, he seems to be the only fish with this problem, my purple tang is fat and healthy.

http://reefcentral.com/forums/album.php?albumid=10557&pictureid=73118

 

[Deinonych]

What do you feed him?

 

[victorcan]

What do you feed him?

I give them a mixture off foods, the main diet was omega 1 till just a few months ago, i switched to OSI Spirolina, but I supplement 2-3 times a week with mysis, Rods, and Brine shrimp. I used to give them algae sheets but have neglected to offer them in a few months