I actually read it in TFH in Jack Watley's section....personally i think its a reliable source and he did say the more you could keep together the better but one is better than two, but three is better that one.... and well if we are looking at natural habits....i dont think you would ever find a blue diamond discus that would survive for very long in the wild, or a piegon blood, or some of the other wild colors that domestic discus display.