My dwarf lion tank is my fav of all time; I keep a fu, fuzzy, zebra, and antennata. So you could do more than one dwarf lion. I also like dwarf angels, a flame angel is no wimp. I like leopard wrasses for their predatory action, mine loves to hunt down live ghost shrimp. The flame hawkfish is a b.a.**** trust me, a great predatory fish. A leopard toby or valentino puffer would also be a good small predator, though personally I don't like them because of their nippiness. An orange or redtail filefish loves to hunt as well, they are cousins to triggers and have a swim style similar which makes them some of my favs for a smaller tank. My perfect small predator tank would be 1 or 2 dwarf lions, a flame hawkfish, a leopard wrasse, flame angel, and one of the filefish I mentioned. Just remember make sure to size everything properly; dwarf lions need to start out small and anything else needs to be too large for them to eat