This has happened twice now. I added a (previously quarantined) new plant to Lavatail's tank and within 1-2 days he gets some kind of alarming looking gunk hanging off his rays. It doesn't seem to bother him, the first time I QT'd him and he ended up getting treated for pretty much everything - in the end, I only got his rays clear by literally pinching the stuff off them. As you can imagine, he did not appreciate that one bit. I have added plants from quarantine to my other fish tanks and those fish do not have this reaction.
Any thoughts on what might be the base issue here? (Two different plants on the two occasions, fwiw. A water wisteria and a hygrophila)
Lavatail is our challenge fish - I secretly suspect he is immuno compromised, which is why I want him to have LOTS of healthy greenery.