[niptek]

to me i think it looks like Rotala verticillaris

 

[legomaniac89]

Rotala verticillaris (actually, Pogostemon erectum now) has really fine leaves. I'd say that's Eichhornia diversifolia

 

[demosthenes]

x2, looks just like Eichornia diversifolia to me too

 

[Hobbes1911]

First thought that popped into my head aswell.

 

[niptek]

cool thanks. i think you guys are right.

 

[Tinanti]

opposite leaves and pointed leaf tips = Heteranthera zosterifolia (stargrass)