I think this is the normal coloration for Severum. Mine are maturing and they are changing to the color in your picture. The juveniles have dark vertical bands and for this reason Severum used to be called "Banded Chicklids". Don T.
They are usual called rokteil severums and sell about £40.00 when young at maidenhead aquatics (overprice fish though!).There was a 7-8 male severum there and i asked how much and they said £70.00