Volitans will generally take to dead food pretty easily. With that big belly he doesn't need to fed for at least 3 days. Lions generally only need to fed a couple of times a week, every other day at the most, until you see the nice bulge in their belly. Even though they can eat larger items it is best to stay with a few smaller items, lions eyes can get too big for their bellies, and they can overeat and get bloat, which will kill them. If you stick with smaller items, they will let you know when they are full. If it's a larger item, they may gulp it down before they realize it's too much.
Get a rigid airline and angle cut the end to skewer some dead food items. Ones to start with, silversides and krill. If you are using the large silversides, angle cut so you use about 1/2, skewer so the head can be facing him when you introduce to the water. If you can get whole pieces of krill, this fools them also, sometimes just dropping it in will trigger him to give chase, or you can use the stick. Eventually he will take shrimp, scallop, squid, octopus; mine even snags chunks of ocean nutrition formula cube foods from the water column.
Those aren;t the rosies that we get from the lfs right, you said you live on the coast and get them for free, what are the minnows you fed him. The minnows we get from the lfs are usually not the best food, live fancy guppies or mollies would be a better choice. If those are wild brackish minnows, that would be an excellent food source until you get him eating dead food. I would just be careful to only feed him one at a time, or 2 small ones.
