Bottom line, IMO. If you're still feeding him live food (guppies & mollies) after he refuses dead; he'll wait for the live. Lions can easily go several days or longer without food. If he refuses the "fake-live-on-a-stick" food; let him wait, then try tomorrow. It isn't unusual for lions to take a week to start eating what you offer.
BTW, if this is a black volitan, and your profile is correct; he'll outgrow your 55 very quickly. These guys grow faster than any fish I know of and can easily reach 12"+ in no time. Not over feeding will slow growth; but that isn't as easy as it sounds. Once acclimated, he should look healthy, but should always be hungry.