I used to raise clowns and really, raising the rotifers is the tricky part. They can be very unstable and there's a really delicate balance you need to maintain. Constantly harvest and feed to prevent overpopulation and starvation. You'll need to keep the fry in tiny tanks at first, and feed SEVERAL times a day with the rotifers. Water changes and constant removal of dead fry is a must. Are your clowns laying on a big rock or something small and removable? Mine used to hatch an hour after lights out on the 7th day like clockwork.
Before you get too crazy thinking about hatching the clowns, get a stable phyto and rotifer population going. Feed the phyto to the rotifers, and feed the rotifers to the baby clowns when the time comes. You'll want a special rotifer screen to strain them out of yucky rotifer water.
