I've had Amazonian frogbit several times in my tank. I love the roots which dangle from it, and the fish seem to like them too - from that perspective, they're better than salvinia (which has the advantage, in my experience, of being more durable) and phyllanthus fluitans (which, in my experience, melts and dies very quickly). I've never had the AF survive for long enough to have it grow, though, so can't really comment on that. To avoid it being buffeted around by the filter outflow, I bought some fish feeding squares to "contain" the floating plants - due to the way these float on the surface, they aren't actually visible when looking at the tank (especially if the sucker is against the back wall of the tank) and serve the purpose very well; however, I think the reduced oxygenation probably contributes to their demise.
