I agree it looks like a Nymphoides, not sure if its aquatica, peltata, or sp 'Taiwan'. I don't think it is Taiwan because it's leaves appear to be floating on the surface, Taiwan doesn't do that.
I will say that Nymphoides aquatica is much more common in pet stores than the other two. We need more detail. A shot of the top of the leaf and the bottom of the plant would be nice. If it is an aquatica then the bananas at the bottom will give it away.