I'll try to get some more photo in a week or two - going out of town. The problem is most of the time he doesn't show that pattern - it is only when he is playing at being aggressive (which is why i don't understand it being a distress pattern) and it doesn't last long - part of the issue is if i disturb them he immediately returns to a grey colour with a bit of pink on his dorsal. They are still quite young - around 3 inch.