Ok, the blue one with the long pectoral fins and no obvious egg spot I will go with being female.She is not aggresive to the others. The black one with fat stubby pectoral fins is odd and at times, after feeding, quite aggressive. It also blows bubbles out its gill flaps and claps them making a noise you can hear outside the tank. This one has blown a bubble nest whilst in a breeding tank. I will post a good clear photo of this one later when I put the tank lights on, in abreeding trap so it stays still long enough to photograph.