ah or suddenly seeing their rival. My other guys flare their colors in a different way, the black (even on the fins) threw me off big time. I've only seen that in severely stressed fish, but these guys seem pretty happy. They tend to show off the little red they have when I come over to the tank, but the black sometimes shows up out of nowhere then disappears as quickly as it showed up. Usually if a fish I'm assuming is a rival swims by, but the black isn't really preset if there's a chase or squabble (which are not often as it is.) They'll be moved to an 8 footer within a month or so, so if that's the issue I guess we'll see. I'll need your guys' help deciding who has the better colors then!