Theres several "Blue" Acaras. IMO, it is probably a blue acara, but not A. Pulcher. Take a look at some pics on google or even rapps' site of acaras, theres several types of blue acara.
I think you got it Darth. The fish he has is missing the orange trimming, and has the white trimming. And has a greenish shade to the body. Face looks similar too. Im willing to bet thats what it is.
I don't think it is a blue acara. I think it is a young female GT down to the colours on the scales on the body... no blue acara has that.
It looks like it has the start of a white trim on the fins so I would guess on the white saum version of the GT.
Who knows it could be a hybrid... they are close relatives
I think A. sapayensis is close, but I think there are too many differrences between A. sapayensis and the fish in question. I think the fish in question is Aequidens sp."maracaibo" (Andinoacarasp."maracaibo" ?) Check out this fish on this link; to my eyes, they look exactly like the fish in question.
Another link, Alf Stalberg's cite, showing a picture of this fish. Scroll down to the very end, for another picture of A. sp "maracaibo". Unlike A. sapayensis, the fish exhibits some red on it's tail fin, just like the fish in question, amongst other differences with A. sapayensis.