There is no evidence this child is a psychopath or sociopath. Just about everyone has done stupid stuff at 6 years old. Feeding the animals in a zoo is something everyone is tempted to do at that age, not because they are a psychopath who likes killing animals for fun, but because it's a zoo and they want to see how the crock hunts.
The point is, there are plenty of sane reasons why people would feed crocks and it's not the same as torturing animals. It's like if you had a pet snake and you feed it mice or rats, you aren't a psychopath for doing that. I would even say you aren't a psychopath if you set a mouse trap and the trap kills the mouse.
People have to be taught right from wrong, and children aren't going to instinctively know it's wrong to feed animals. Also according to psychiatry only adults can be diagnosed as true psychopaths. This is because as children, 100% of all children exhibit psychopath like behavior until they reach the age of reason where they grow a conscience and develop their frontal lobes.
So no, I don't think this kid is a psychopath. If this kid were 14 and still doing stuff like this then I'd be more concerned. And I don't think this kid needs therapy. Yes it's wrong to feed animals in a zoo, but it doesn't take a genius to understand that 6 year olds will do stuff like this.
A psychopath is an individual without a conscience. A psychopath might kill and torture animals as a child, but so do normal kids. The difference is the psychopath enjoys doing it while the normal kid will grow a bit older and start to regret what they did.