Oh no and may have started as bacterial. Swollen areas or bumps on eels can have many reasons:
- Parasites below the skin (marble like appearance),
- Internal bacterial infection (has to be treated in a hospital tank with antibiotics),
- tumors (some will go away by themselves, some can only be treated by antibiotics),
- Constipation (swelling at the belly, use Epsom salt; don’t feed much krill, but rather mussel or crab meat once you get it to eat again)
- By any chance do you have a lionfish or rabbitfish that could have stung it??
Test and assure water quality has not deteriorated or false salinity whereas it is higher than your reading is showing.