He needs to go in a hospital tank. Increase temp to 90 and treat with Metronidazole 500 mg per gal. Do the biggest wc you can do and re dose daily for 10-12 days I’m pretty sure. Maybe someone else is certain? I’ve also read 12-14 days or until fish is eating again. I had a heck of a time finding a gram scale till I went to a head shop. Ha ha
Patty