the large black and grey ones are convict cichlids..look to be all male from
the pictures - females have red/orange tinged abdomen..not sure about the
white guys. If the convicts are all indeed all males, you may need to make
separate "drops areas" in the tank to ensure everybody gets a fighting
chance at the food. IME convicts like most cichlids appear ravenous and can
be aggressive feeders; subdominant males and the smaller white cichlids may
be unwilling/unable to swim into a throng of feeding convicts. They'll eat
whole flakes, no reason to "crumble" them up
HTH

lila pilamaya