Either a genetic defect (less likely as these are usually more gradual, gently sloping starting from the eyes) or a broken snout.
So I've had these 2 for about 2 1/2 months and my only issue is that I did not get to pick the fish out personally. I have one perfect fish and the other has the missing fin and broken nose since I got it. My girlfriend likes the damaged one more but it will always bother me. It seems to have an upward curve in its spine at time if it's eaten a lot too that the other one does not have. The most noticeable difference between the two is the growth rate. The damaged fish is far bigger in size at this point. Probably by 2 inches in length. I did have a third tsn from a local shop but I think it got stressed to death by the tig I had in there for a while. It's been moved to another tank and it seems the other two are doing well now. I'll try to get better pics soon but they hide all the time and it's tough.
They were the post before. 2 pics.