Daughter shut down her Edge tank deciding she didn't want to have fish after all (now mine) - don't know why with an entire pet store she picked out a sickly feeder goldfish. She wanted to save it (we have a pond). We took out the fish and what had been three Cories. There was only one Cory, we stirred and stirred the sand and there was only one. I figured they had died.
Came back later and looked again and didn't find anything. After a few days she unplugged it and it sat in the corner for about 2 1/2-3 weeks, no light no air, no heater and no food.
I needed extra room as my momma guppy was going to have babies, so i asked her if I could use it until she sold it she said yes since it needed to be cleaned out anyway. I walked in the room and thought I saw movement!
Scared and mortified, I ended up rescuing a little Cory. There was a zen structure in the tank and best I can tell it hid inside of the piece (even checked the filter). I had lifted the thing up and shook it numerous times though I didn't even know there were holes in it (daughter put it together). OMG it got like 63 degrees or less!!!!!
Poor baby!! She is doing great and nearly doubled in size in the past year! She was reunited with her buddy, a boy and they hang out together all the time.