What else can I feed my crawfish(crayfish, crawdad) besides shrimp pellets?

You can feed him anything that he could reach. Crayfish love live fish so you could try buying a couple of guppies. They also enjoys algea disks, worms, shrimp (actual not the pellets), The key is to vary the diet to get the proper nutrition. I would not use the shrimp pellets period and would recomend tetra's TetraCichlid Mini Granules. Don't give him many and they sink to the bottom. This should get him out and looking for it keeping him active.