Update on this post: yesterday out of nowhere as I was feeding frozen mysis shrimp to the clowns that share the tank with the lion, the lion swam out and started eating the frozen! He did so again today. For some reason, after over a month of rejecting anything but live he has reverted back somehow to enjoying frozen. Honestly I think the dead ghost shrimps that I didn't remove from his tank somehow helped. I think eventually he decided to eat them even though they were dead and now he's back to tolerating the frozen! Super happy about this. He's much more active now as well