As far as messing with the substrate i did that once in my 80g reeftank and within 3-4 hours i had 80% of all livestock dead,lots of toxins down there.Hard lesson to learn,like getting kicked in the head.Back on the horse!
Sorry for your loss! Looks like a mass murder photo.
This story makes me rethink the priorities for my current set up, I have a couple of small pumps running now, but I think what is helping my situation is the water flow from all of my filters jets into each tank causing turbulent bubbling on the surface, helping the tanks inhabitants...That and one tank is full of air breathers (Knifes and Bichirs) and the other has hardy fish, plecos corys and barbs currently...
Easier for a newb such as myself...
Sorry for your loss! Was the tank overstocked? I have had power outages and not lost any fish. I do wonder if the oxygen demand would not have outweighed the supply were there fewer fish. Just a thought. No kicks to the head, just my sympathies.
You can't expect to post a pic like that and get anything other than sympathy. We all make mistakes, it's obvious you weren't trying to do kill them. Sorry for your loss, but as another poster stated, you now get the fun of restocking. Not that it's much consolation, but picking out new fish is always exciting.