Koralia sucked fish in, now he's swimming weird...

[Sumdood]

Hey,
I just found my filefish stuck to the Koralia and nudged him off and now he's gone dark brown in colour and swimming near the bottom looking like he's dying. He was fine an hour ago and has been eating for the last 8 months so pretty sure its because of the powerhead and all the other fish are fine. I've put him alone, anything else I can do to better his chances?
Thanks