I'd feed it small silversides or pieces of shrimp. The LFS I worked for fed shrimp. We always bought the texas shrimp, uncooked, like 35/45 size.

Just get you some Zoe and soak the shrimp till its good and green. Then feed one to three pieces just small enough for the lion to get its mouth around and leave it alone for 3-4 days. You'll see the belly go empty after a day or two and you'll know its time to feed again.

If you really love watching it eat live food, give it a very special treat on very rare occasions so it doesn't get away from eating the frozen stuff. I always enjoyed feeding the lions a small cichlid cause they are fast and tend to be fun to watch getting eaten.