Congrats on you new niger cat. These guys are so much fun. As they continue to get bigger they become more and more sociable until they are staring at you begging. For me these guys went from an interesting, weird fish to one of my favorites. As for food, they love their pellets. My guys eat sinking cichlid gold, massivore, NLS jumbo and large fish formula, algae waffers, and they even suction floating food off the top that is meant for other fish. They'll sorta eat small chunks of tilapia, but they like their food small. They do exactly what you talked about with not just swallowing pieces of shrimp and fish. And, yeah. My big guys are about 2.5 years old. Their growth slowed down about 6 months ago, and they've been putting on serious mass. I suspect in a couple months they'll start lengthening again. I'll be interested to know how they do in pond liner.