try to feed something saltwater. ghoast shrimp will work to try to ween him on something else. better than nothing. but something like white shirimp will work. even that fire shrimp
is it a dwarf zebra lion? it almost looks like a V lion and not a fuzzy dwarf. so im guessing its a dwarf zebra. it looks more like one, but the pics are blurry ;-)
the tank looks great though!