Hello,

Did it look like this:
http://www.drta-archiv.de/wikidis/in...hyroidTumours?

Maybe the fish had a cyst inside his body, a tumor or something like this
which pressed on a nerve for some time. Dark coloring of parts of the body
is often caused by something like this or ill nerves.


--
Grüße
Norbert (Heidbüchel)