I use frozen silversides and freeze dried krill for my Dwarf Lion. On occassion, he will also eat up big chunks of frozen Emerald Entree that I feed the rest of the fish. I also treat all the fish with live brine shrimp every couple of weeks, and Rubble (my lion), likes to pick out certain ones and stalk them, then eat em up.
I was lucky, it only took several days to get him eating. I started by feeding him small amounts every day, instead of large amounts ever few days. This way, he has able to learn the feeding "schedule" easier. Now when I turn the lights on, he knows its feeding time and races right up to the top right-hand corner of the tank to get his fill lol. These fish are not dumb by any means, and will LEARN the routine. Rubble eats right out my fingers. I feed him between 2-4 krill one day, then the next I feed him cubes of the frozen silversides. He'll gobble up anywhere between 3-6 pieces of that.
You have to entice your Lion with foods like this. If your becomes atleast somewhat active and swims to front of the tank, try holding a piece of silverside in the water. If you can get him to know its there, drop it and let it fall right by his face. He might be hungry enough to eat it up. If so, once they get a taste of the "menu", they begin to learn fairly quickly.