Blenny died mysteriously

So my red scooter blenny went from swimming around and munching on pods late last night to this morning not moving and gasping. Mandarin is just fine all my parameters are good nitrates in check and there's plenty of surface disturbance. Pods are all over the glass still as well. I'm real bummed we had him for over 6 months was beautiful and never showed signs of sickness. If anyone has insights so this doesn't happen again and my mandarin stays safe I would appreciate it