We also have a dwarf lionfish who eats every other day. We have taught him to eat silver sides (bought frozen) They say you should soak them in a special vitamin enriched solution but we haven't done that yet. We use the rosie reds as treats. He will gobble up 3 or 4 at a time if we let him.
We like the live food for the benefit of other essential enzymes not found in frozen. It also gives him more exercise to chase down the food. You have to be careful not to overfeed.
c-c