I've had java moss in my terrerium for about a year now, I like it a lot. I have an albino axolotl and a tiger salamander. For some reason though I can't seem to grow it on rocks! but besides that, it will grow. I've read that it also collects small particles, which is beneficial to shrimp and baby fish. When my guppies have babies in my aquarium I'll put a couple babies in for my axolotl to have fun with after they get a little bigger. I actually recently bought some 'green blanket moss' from Taiwan (on Ebay) already attached to a smooth rock about half the size of my palm.