Just one opinoin.......I don't think there's a stand-out difference in "nutritional" values of crappie vs. catfish....or any other fish. I'm not a dietitian. But you can goole up info relating to the nutritional value of fish (in general), and it's determined to be a stand-out "brain food".
I do know this........if it's that advantageous for the brain, as much of it as I eat, I should be another Einstein ........... but if it ain't good for ya, I'm a walkin' dead man.
If nothing else, I think just gettin' them suckas to take your bait is worth more than any nutritional value there is.........it just soothes my soul.