if my black isn't beside my red, it will cruise the whole tank, but i find that the red will always sit at the surface of the water next to the xp4 outflow and lets the current blast at it's tail. kind of funny to watch haha. but whenever someone comes by, it will swim off and do it's own thing like it doesn't want you to see it there.
I remember when i had a PG, the shine would start from the tail as well, but for the red i have now, the colour is developing from the head back to the tail.