What The Hell Is This???

[need2ball]

I have a couple small black arowanas, about 4 inches, I've had them for about a week and a half. One is getting really skinny and the other one is really thick and healthy but I noticed something attached to its body. Looked like a piece of string or something.

There were 2 I pulled one off and it broke. The other one was under it's mouth and I pulled that one off and I think I got the whole thing. Here is what it looks like. WHAT THE HELL IS IT??

 

[Arachnar]

It could be an anchor worm if you said it was rather stringy, they often attach to the skin of the fish and suck blood or whatever, try googling it for more info.

 

[Gr8KarmaSF]

Fish lice?