That poop indicates there may be a bacterial infection. Can you obtain an antibiotic? Do you know a vet you could ask? Do you have any leftover people antibiotics or do you know anyone who might have some?
I don't know if you can order antibiotics on line from BC, but here is where I get mine. https://pet-healthcare.revivalanimal.com/search?p=Q&ts=custom&w=fish antibiotics
I don't know if you can order antibiotics on line from BC, but here is where I get mine. https://pet-healthcare.revivalanimal.com/search?p=Q&ts=custom&w=fish antibiotics