Both fish and chicken are excellent sources of lean protein, crucial for muscle growth and repair. Chicken breast offers slightly more protein and leucine per 100 grams, potentially aiding post-workout recovery. Fish, while containing slightly less leucine, provides beneficial omega-3 fatty acids that can enhance muscle protein synthesis and reduce soreness. Chicken is lower in fat and calories, whereas fish varies in fat content but is generally easier to digest, offering sustained amino acid release.