I havent got a clue what that is, but I would issolate the fish.
Here is a link it might help out.
Might want to put this thread up on tropical chit chat too, someone might know what it is. http/edis.ifas.ufl.edu/BODY_FA041
Them coiled like worms can be flukes to this.
Nematodes are frequently coiled in the flesh of the fish, either in elongated ...