I introduced Java Fern to a brand new tank.
It is nearly done cycling, and during that time (22 days) they have gone from super lush to what it looks on the above pic.
But they are not dying. In fact, there are a lot of new sprouts growing from the leaves themselves. As if the leaves' twigs had become rhizomes.
I posted about this in
this thread on www.ovas.ca
See on the first picture, the leaves have become brown and even started to decompose.

