I looked into TFH's 1990~2000 archive and found a few related topics but cannot be sure if that's what you're looking for. There wasn't any mention of plague either.
Are Our Discus Populations Threatened by a Giant Flagellate? - 09/91
Chemical Treatment of Discus Diseases - 04/91
Common Parasites of Discus - 01/91
Good luck with your search and update us when you do find the details.
Bookmarks