| | Re: Irish Moss?
I'm willing to bet what your speaking of is Pearlwort. It can do fine in a Kweichowensis tank so long as you have good drainage. This can be done by simply not allowing the substrate to compact and not allowing it to get sloppy wet. Adding sand and sphagnum to the sbustrate helps keep it aired out and helps with drainage. It prefers full light to slight shade.
Azhael is right, it is popular in rock gardens but again with proper drainage in the substrate it can do well in a Viv.
The only one left with out a chance is the one who's last chance has been taken away.