+1 on the java fern. In less than two months, theres four of those new "baby" plants grown off of mine and three or four inches of leaf growth and a new leaf.
Maybe corkscrew val??? Thats iffy, mine has barely grown but is surviving well.
You could try swords or crypts, personally i love my crypts. Each plant has 2-4 new leaves (from my understanding that a good amount for a rosette plant in this time) and about an inch of leaf growth in the original leaves.
My favorite is pennywort. You can attempt to stick it in the substrate but anything below gravel will rot. I float mine, and on a stem I've kelt track of there are 11 new leaves and a bud, plus the original 5, and it stretches the length of the tank. Every day there is a visible difference in leaf size, root size (grows below each leaf), and any new buds opened. It could also be wrapped around driftwood for an ivy type of effect. The further from the top, the smaller the leaves.
You could probably do anacharis, anubias, hornwort, or onion plants, but I havent had experience withthese. and mosses like christmas moss, would make a good wall while java moss would make a carpet.
