Thats a beautiful fish. Im going with Abialos cause Altifrons have spots on their tail not stripes. Could be a mix of the two. That fish does have a scale anomoly on its caudal peduncle.
That's a very interesting fish. Does it ever show the lateral spot and if so can you get some pictures? And do you know which country it (or it's progenitors) was imported from?
I purchased this guy and 5 others as 1" fry. My LFS had them mislabeled as red head Tapajos. I wish I knew their origin. I have never noticed a lateral spot. Here are some pics of the group from last July:
I'd go with G. altifrons too b/c the lack of the lateral spot. Some G. altifrons variants do have somewhat stripy tails, but the lateral bars on these fish look unusual. Beautiful fish no matter what they are!