I feed my lionfish Tetra Jumbo Shrimp and he loves it. If yours won't eat anything he's either still adjusting to the tank or he didn't have a good shipping experience. You could also try Mysis Shrimp it suppovly encourages even the pickiest of eaters to eat, my lionfish likes that too, I feed Frozen Mysis shrimp to him sometime. I've had my lionfish for about a year and a half and twice he jsut stopped eating for 5 days, but on the 6th day he chowed down and ate every day after, maybe hes binge eating. Good luck!!