My african pike hasnt had any problems with his current tankmates: Marble Goby, RCK, Needlefish, and even a False Jaguar Catfish. In the past i had him with a Spotted pike-Characin too, I would be careful with keeping these two together as the Spotted Pike was considerably less agressive at feeding time and at night the African would chase him a bit. Nothing big, just a single scratch during their time together and a couple pinhead-size nicks in the fins, but still.
As far as feeding goes, mine will eat anything that moves very much, and I put in 5 goldfish over half his size to stop the picking on the Spotted pike-Characin and they got eaten, but im not sure if it was him, I bet so though because he spent all his time messing with them. I haven't tried to pellet train mine yet, I enjoy feeding him live too much and as of yet it hasnt gotten too expensive.
I have noticed some weird behavior with mine and was wondering if anyone else saw this with theirs. When he notices that I'm in the room, he goes to the front of the tank and swims back and forth and up and down for 2 or so minutes. When I sneak up and watch him when he hasnt seen me, he never does this.