Whats wrong with new purchase?

[jsc4354]

Let me start by saying how embarrassed I am for posting this BUT i'm guilty. I bought a new fish for the tank without doing a good job of checking him for any diseases prior to buying. So, when I got him home I noticed this red spot on his side with what looks like a curly thread coming out of it. Not sure if it is a worm or his insides. Can you tell from this pic? Thanks John C.

 

[jsc4354]

Update, I pulled the worm/parasite off before placing in the tank. However, after several days it grew back. Any idea what it is?

Thanks,
John C.

 

[jsc4354]

This sucks after a little over a week I found this guy dead in my tank. I was hoping this was an external parasite that would not harm it's host but I guess I was wrong.

John C.