Bariene Tang

[phar]

I have a Bariene Tang that's been kind of blah the last week. He's only about 3 inches long. I have had him for about a month now.
The only thing he's eating is seaweed sheets that I put in the tank. When I drop in fish food he'll swim up to it but never eat it. He's not actively grazing either which is unusual for any tang.
He had a nick on his upper lip but that is healing up.
The last two days, he's having some sort of seizure every once in a while. The fish is definitely stressed. I'm not sure if I should put him in quarantine and give it a round of medication.
I really don't want to rip apart my display to get the little fish out of there... anyone know a trick for catching a fish without a trap?
Thoughts?