Thusly "D&M" Spake Unto All:

Hmm... first thing I seen was mal-nourishment when I looked at the photos.
I'm specifically looking at the spinal deformation behind the dorsal fin. If
that's due to UV, that's quite interesting, I'v never seen that effect
before.

Yes, he was the runt of the litter, and did have other issues prior to
coming down with this disease - but they're unrelated to this disease.
His siblings, those which are still alive, look e.g. like this:
http://mikes-machine.mine.nu/specime...e_DSC_2139.jpg