Flexibactor columnaris aka Flavobacterium columnare aka Duck Lips, with the more virulent strains of this bacteria ones fish can be dead in less than a week, but that is certainly not always the case with less virulent strains. There are several strains.
More info (and pics) can be found on this disease in the past discussion.
https://www.monsterfishkeepers.com/forums/threads/15-umbee-sick-help.543236/
It may have some other opportunistic parasite probs going on. Would treat for duck lips first as it’ll die from it before the stringy poop issue.He also has clear stringy poo... not sure if that helps determine what you think he may have.
Furan by itself isn’t enough to treat duck lips. Try getting some broad spectrum antibiotics. If not then consider putting the fish down with some clove oil. The fish will suffer and be a source of I faction for other fish.All of these meds that are recommended seem so hard to find in Canada... ? I should be able to get the furan.
I just did a 5 day treatment of metronidazole because I thought he had HITH but I’m starting to think maybe it’s not.