http://i35.photobucket.com/albums/d168/ ... C04272.jpg
maybe this is the answer
The black marks in wild fish are caused by the intermediate stage of a parasite. It is in the bird, it drops faeces in the water which are picked up by the fish, expressed in black markings on the side. Here the parasite will stay until the process is continued, and the fish is eaten by a bird, and the cycle starts again. In the case of tank breed fish, this can’t happen, and if one has a wild caught fish with some black spotting, as far as I know it will go no further than this, as it requires the fish to be eaten by a bird.
but there are reports of these spots spreding in the sides, I guess from badly infected fish still showing more and more new and larger spots.
It steems it has not reached any suplier I know but may be because some fish are kept in open pools before export.
But the report on F1 fish is VERY worrying if true.