The Predators announced the trade Thursday after putting McGrattan on waivers Tuesday. McGrattan, who agreed to a one-year deal with the Predators last July, had not appeared in a game this season for Nashville and recently finished a two-week conditioning assignment in the AHL.
Nashville gets Piskula, who has played 10 career NHL games with Los Angeles and Calgary with eight penalty minutes. He has played 370 career AHL games with 70 points (8 goals, 62 assists) and 320 penalty minutes. Piskula, 28, will report to the Milwaukee Admirals in the American Hockey League, Nashville's top developmental team.