Is he eating and pooping normally? Can you post a picture? Was he wild caught or cb? Does his previous owner know anything about it (birth defect, injury etc). Without knowing more / seeing it it's hard to say if it's a problem.

If he's eating and pooping odds are that it isn't life threatening. If you're planning on breeding, then it would be important to know it the deformity is congenital or the result of an injury.

-Alice