Glad that went well, I'd be so nervous keeping an electric fish!!! Glad you didn't get (or perhaps feel) a shock.
Judging by his reaction, I bet he'd be easy to hand-feed, and if he's gonna act all uber territorial about his food, it might not be a bad idea to do so - cuz' then he'd see your hand as a food-bringing friend and not a rival. But. . .that's a SCARY thought, cuz' I don't WANT you to get zapped by your fish!!! I wish there was a way to put him in a battery charger and check his output somehow!