Same way u get rid of Arowana's gill curl.. i suppose? Tranquilize it place on a damp towel and cut the curls off? Then place back in tank with pimafix and medifix to prevent infections. Also make sure the fish stays moist during the surgery.
Maybe your fish lacks swimming space? or lacks amount of oxygen in your tank and bad water quality? I'd start off with a 50% water change first before doing anything else.