How and what do i feed a lionfish?

They can be trained to accept krill, formula one, etc, on a stick (bamboo skewer). It takes a while, but you'll save money in the long run, tank'll be cleaner, and you won't risk introducing disease into your tank. And, if you feed them only fresh water fish (guppies) they'll get a protein deficiency and croak on you. Occasional live feedings are entertaining, but your fish can actually choke on a live prey too big for it.