Crappie are notoriously unpredictable; use them at your own risk. You have been provided advice based on experience, but there are no absolutes. Every pond is different. Please keep us updated on the pond's progress. IMO on a percentage basis, the NPike will eat more smaller bass & perch than crappie. Pike are selective predators. Pumpkinseeds will be a variable in the fishery. The more fish species present the more complex the food web and management becomes. With your current planned species IMO you will have a hard time maintaining minnows(true Minnows/shiners) for the long term without one of the nonpredators(panfish) becoming overabundant.
""...conclusion that the fish need structure for general health and happiness in life. It makes sense as all animals get bored walking around in circles in a pen. They eventually start seeking out things to break or play with."" I'm not so sure this is true for animals. One has to be careful to not apply human emotion onto animals (anthropomorphism).
https://en.wikipedia.org/wiki/AnthropomorphismI agree that structure and habitat aid in the survival and thriving of animals but not so much for "general health and happiness".
The size of the brain MAY and the advanced evolutionary development of the animal have an effect on "emotion" or mental state in animals. Monkeys show more "emotion" than for example insects or fish.
