I had a plec that I managed to train, or maybe he just knew the best place to wait when it was feeding time. There was a large flat rock in our tank and every time I lifted the lid on the aquarium he would swim onto the rock and wait till the sinking pellets arrived, then he would play shove ha'penny with em for a bit before taking one to his "lair", which was the back of the filter. I named him Lurkalot lol. He was my best fish ever, came out mooching every time someone went near the tank. He loved a bit of cucumber too and would hang upside down off the pieces floating at the top of the tank.