I put a couple of java ferns in my grandmothers tank yesterday. They have a lot of "starts" growing on the leaves. I am thinking about getting a ten gallon tank to harvest and raise them in to put into my 120 G when I start it after Christmas. I was thinking just some sand and weighing them down so the roots don't attach to gravel or driftwood since I will be removing them in a few months. Any other ideas?? It looks like one of her Mickey Mouse platty's might be prego so I thought I might get something set up for the fry and the baby Java's.

Relatively simple. You can do that or just plop them in the tank while they grow out.