Do not hand feed. If the animal is not willing to eat you can feed enriched ghost shrimp until weened. Use clear rigid tubing as a feeding stick. 2-3 times per week is plenty and feed until you see a small bulge on the side of their stomach/body. What lionfish do you have? Some lionfish prefer more crustaceans in their diet than others, but for a general list I would try feeding in frozen (thawed) form: silversides, capelin, shrimp, crab, squid, and other marine fish. You may also need to add a vitamin supplement once weekly such as selco and/or Thiamine E.