Volitan lions can be pretty easy to start eating, even dead food. You just have to make sure it's moving within the water column, if it hits the substrate, you can flick it up with a feeding stick to attract his attention. If necessary you can start with live ghost shrimp, freeze some get him eating the dead, then they mostly will start taking a variety of dead foods. You can drop it in once you get his attention, or use a feeding stick. I feed my volitan shrimp, silversides, scallop, squid, octopus, krill and he will grab any chunks of whatever catching his attention while floating in the water column.
As far as size goes it might just be relative, I've had easy success with itty bitty ones and very large ones, so I say whatever catches your fancy. Since you are personally collecting him you should have none of the common ailments commercially collected specimens have, like parasites, so feeding really should be pretty easy. Just remember to keep the food moving, live prey size chunks but not overly large. Sounds fun.
Just sayin'.
