I have 3 in my cichlid tank - they are nearly full sized adults now, going light grey with black spots. Up to this afternoon all 3 of them were very friendly towards each of the others. Suddenly they've started headbutting - not necessarily the largest, but one of the smaller ones. This one is very nearly completely light grey (the largest of them is still dark) and he/she has started head butting the other two. Is this territorial fighting? and if so, should I separate them. (the only way to do that would be to take the others to my lfs) or will it settle down soon. I don't know if the fact that there were no lights in the tank for a week and only today I got the new set, makes any difference. Any advice please!!!