Place the tilapia on a rimmed baking sheet and season with salt and pepper. Bake until cooked through, about 10 to 12 minutes. Let cool and flake into small pieces.
Mix the mayonnaise, eggs, dill, and mustard in a medium bowl. Fold in the tilapia and panko.
Form the mixture into 8 cakes and chill for at least 30 minutes.
Heat the oil in a large nonstick skillet over medium heat. Cook the tilapia cakes until golden, about 3 to 5 minutes per side.