Get some live pods. Target feed it several times a day putting a few in front of him when he is resting on a rock. They can learn that the tool you use to feed them brings food. Put as much live rock in the tank as possible. Put a bunch of cheato in. Gradually add frozen to the live and one day you will see him suck it in. The trick is to have enough for him to hunt to keep him going until he learns to eat frozen. Choose as many types of frozen (small) as you can find. Cyclopeze and roe (eggs) will fit into his mouth easily. last but not least find one that is already eating and put him in to teach him.
good luck
