be careful they have big mouths i had a native catfish (that was exsactly like that except color of cource) and i went out and bought a baby silver aro for $20 and the catfish ate it! but it was my fault and i lost 20 bucks my catfish was 6" and the aro was 3.5"
i heard that if you actually massage the gill it helps. haha. but increase swimming space helps. and i do a 5 gallon bucket water change a day. and it is going away. somewhat. it is curling over in one spot even worse now.