Glow light tetra swims in spirals

[Jnam]

Ok its probably not funny to everyone, but I have this wierd little glow light tetra he cant swim in a straight line. He rotates kinda like a bullet does or maybe a spoon shaped fishing lure. He happy and healthy besides the wierd swimming. Its not always been this way, one day i found hime chasing his tail litteraly swimming in fast little circles. My thought was he was on his last leg or would that be fin? Anyways I QTd him he had no obvious signs of infection. But hes been just spinning along for like a month now eats and has full color. I want to move him back to the community tank but i am afraid he might get hurt or picked on because of his disability( seriously the bigger fish like my angels may think he is food) Any suggestions? Should i put him down or just let him hang out with the shrimp and snails in the QT tank? I wish i could get a video its the funniest thing watching him swim... Are fish like dogs? you know if they get hit by a car and lose a leg they just adapt and keep on going happy and healthy. Let me know what you think or if anyone knows of a cure>?