I think I saw someone mention above they couldn't keep their CBB alive because it was being outcompeted during feeding time.
They will peck at rocks all day long but it's not enough for them and do need that extra feeding. They will get to some food if it's broadcasted but they are much more timid and potentially not enough that way either. Some will depending on CBB and other tank mates. Good options for those not getting enough food is setting up something like a feeding station PaulB has setup feeding live baby brines in, some will setup a feeding station with PVC and holes for them to get their mouths into, or hand feeding.
I like hand feeding mine. Usually mysis, black worms, chopped up clams, or muscles. I cut the tip of a pipette off so only it can get it's mouth into it. Other fish try but I suck it back up in there.