I don't think there's anything "weird" about that fish at all. It looks exactly like the regani's i see Rapps carrying, except for the black blotch/stripe is more prominant in your case.
Nitrites, stress, water chemistry in general can impose changes to a fishes appearance. I've seen several different CA/SA swim around with solid black heads and regular colored body, only to change back to the norm once the chemistry is right