This is a much-written-about fish. After reading its profiles on Planet Catfish (both Cat-eLog and Catfish of the month), ScotCat, SeriouslyFish, Aquatic Community, FishBase, etc., there should be few questions left.
Looks like you got lucky and obtained a well conditioned specimen, plus your tank is wonderful for this fish.
I'd not feed it (or any fish for that matter) live feeder fish.
The fish is likely Sorubim elongatus (with a 1' max size), not Sorubim lima (with 2' max). If you are interested, I can explain why I think so or maybe you have already come across my humble write-up on this ID matter on MFK or PCF.