Still too blue for a clear view, but I can see some growths that look like tiny round grapes. Can you see those? They seem to be protruding from the fish. Bacterial diseases are usually erosive, that is, the bacteria eats away at the fish tissue, making it less. In this case, it looks like it is something growing larger. If this had developed slowly or weeks, I would say it is a cancerous growth. However, you said it showed up suddenly - that could mean that it is a fungal infection (but those are really rare). Do you have a treatment tank available?
jay
