"NetMax" wrote in message
.. .

What I would do is get my razor blade out (or a sharp exacto knife) and
open them up (welcome to the world of forensic science). There are
several fish books on diseases which show colour pictures of dissections,
so that you can differentiate between some of the types of parasites,
bacterial infections and ulcers.

Only problem with those books, is that either a multitude of pictures look
like the growth in question,
or none or them do :-)

Once identified, you will have a better

Good luck.

Graham.