Lethargic Foxface

[Curren007K]

4 year old Foxface suddenly very weak, he was stuck to the side of my wavemaker.
No open wounds or torn fins, there are bumps from the wavemaker cover though.
I've unplugged it and now he's barely swimming towards the top of the tank...

Parameters fine, no signs of skirmish with other fish...

Any ideas?

 

[Curren007K]

All other fish are fine, he's always been an aggressive eater of nori, flakes, mysis shrimp, brine shrimp, etc.
He was fine yesterday...