But even dwarf lions get 5 - 7 inches so any thing that will fit in there mouth will be eaten. There will be no guarantees with this fish, if you house smaller fish with a lion the chances are good it will be eaten. I have a 90 also and a lion grows fast but you can also house just so many larger fish in a 90 to go with the lion.
My lions are in my 300 but I start them in my 90g Reef, I want to make sure they are eating before going into my other tank.
I keep a Kole & a FileFish in my 90 reef and nothing else but I would not put chromis, cardinals, wrasses and so on in it.
Kaye