Post pictures of your beloved catfish aquaria here. Also good for pictures of your (cat)fish rooms or equipment discussions. If you are posting pictures of identified catfish, please do so in the appropriate husbandry and reproduction forum above.
With your experience I reckon you would recognise something straight-forward, so this might be the effect of something unlikely... such as... maybe something toxic found its way into the tank? Or contaminated food? Or contaminated water at the last waterchange?
Looks nasty. Maybe do a bi-i-ig water change for starters? I hope your megladoras pulls through.