I used to think the paler of my Khullies was being shunned because I never saw him out with the others even at feed time. So I tried to observe him in the conditions they say Khullies prefer, so one early morning with no light on in the tank & just one table lamp on the other side of the room providing just enough light to see into the front of the tank, I went to see whether it would be out & there it was joining in & doing exactly what all the others where doing happy as could be. My thinking is, possibly this colouring make Khullies of this type more sensitive to light. So if like me you sometimes get up silly hours to go to work try with little light seeing into your tank.