you had pics a while back on piranha fury.. they are gone now i just checked.. what kind of filtration are you using..
i know of a trick that cures gill curl fast but i doubt you wanna risk it with your piraya.. i know an old asian guy that cures gill curl on his arows by increasing the water flow with giant pumps to tire the fish out.. then he will remove the fish and put it into shallow water,then he will start massageing the operculum gently with his fingers.. what it does is damage the operculum and causes them to heal straighter, then you repeat untill and it straightens them out.
you might now up missing a couple of fingers though if you try that on a piraya..