I've got Amazon Frogbit in my tank kept in place with a piece of cotton tied to limpet clips - looks beautiful now the roots of grown and the fish love it!
im soo jealous of those with frogbit!! i heard all you have to do is plonk it in and it will be fine. (as long as light and water is ok!) or those with Salvinia natans, never seen it in any of my lfs, and i go regualary
I have both water lettuce and Salvinia ( the roots of which can be seen in the second pic in my signature ) and although I don't breed fish, the trailing roots would be great for fry. Crystalwort may also work.
The best top fry hider that I have found is a big clump of hornwort. For the lower levels of the tank it would be a toss up between guppy grass and java moss. They are very much alike and both work great.