I am going to try to take better pics of my Severum later. Since the only ones I have are blinded by the sun. (Outdoors tank) but here is a rough pic.
I've found that mine gets lighter color and you can almost see barring when he is relaxed and not tangling with one. But when he gets agrressive or harassed he gets very dark and black.
Heh my two old men. The two oldest fish I own. My red Oscar and this Severum. Severum is at least 7yrs old and the O is over 10 I don't actually remember when we got him. But I know I bought this 150g 8 years ago, and I had already had the Oscar in a 90 for a few years prior to that.
*Edit* after I wrote this I started thinking about it and doing the math. And the Severum is actually closer to 10. And the Oscar is closer to 14 or 15. Heh time flies.