…and that is more or less the same as I posted earlier. Only it was not believed.It looks like lymph to me too, newly shipped and added fish seem most susceptible.
Since it is viral, there aren't any effective medications.
My case came in after some V. breidhori were shipped.
With lots of water changes, and after settling in, the fishes immune system fought it off, and the case quickly went away.
It is ubiquitous.