I've kept pirate perch a few times. They seem to often have heavy parasite loads, so keep an eye on him; I suggest taking him out of your sunfish tank and putting him in a quarantine tank with some plants or other cover.
My guys would usually eat frozen bloodworms or mysis, but only if it was in the water column; once it hit bottom they ignored it. Some individuals would take crumbled cichlid pellets. All enjoyed scuds, isopods, juvenile ghost shrimp, and various other small live inverts; I imagine they would go for adult brine shrimp as well.