My cory's dorsal fin is black in the upper half, but no other pictures I have seen of C. zygatus have this. The difference in patterning cannot be age-related because I have seen pictures of both juvenile and adult C. zygatus, and neither of them have this black area. I also looked at many pictures of C. rabauti, and that didn't have the black area either.
Does anyone know if my cory is C. zygatus or not? And if not, do you have any clue on what it could be? Could it be an undescribed species?
He was the the only cory in the whole store labled as C. zygatus, so I was not able to compare him to any other corys.
Thanks for the help! Here is a picture of him:






























