A lion is compatible with eels. The thing with eels is they don't take up much space so it gives you room to add more fish. Your problem is that the other fish is a lion. What kind of lion makes all the difference because some lions get very large and some others stay relatively small.
it would be a dwarf lion and now i want to know what and how many other fish i can add what about a powder blue or a lunar wrasse or a picasso or a foxface help me put together a good combination