As someone who's very jealous and trying to get ahold of these fish myself, I think those are indeed Hisonotus. I've heard they can range from green-brown coloration, and the intensity can vary depending on their environment (if they are in a heavily planted, green tank or a blackwater low plant tank or whatever) and that their color can also vary by gender maybe? I may be stretching on the gender thing, but a seller I know seems to differentiate between his males and females by color: males are more brown, females are more green. Here's his website:
http://amazontropics.blogspot.com I think if you have any questions, you should ask him, but from what I've seen of the species, those look legit.