Yeah. I went through something sort of similar (all of my fish dying) but it wasn't because someone broke my tank. I asked my mother to pick up dechlor for me at the store because I was doing a larger water change, probably about 50% or so. And she brought it back and I poured the said amount into the tank after re-filling it. Come to find out, it wasn't even dechlor.
It was in the same shaped yellow bottle that I have been using for years, it just had a red dot on the label instead of a blue dot indicating it was a product to lower the nitrates in the water and doesn't act as dechlor at all!
I didn't notice that until almost all of my fish were dead. I went out for a few hours and came home to find every one of my fish lying on the bottom of my tank. My 10 inch plec jumped out and was laying on my pillow of my bed. He was dead too.
I scooped them out one by one and put them into a bucket of water and none of them were alive.
My oscar was laying on the sand with both eyes clouded all the way and he was not moving.
I buried all of the fish out back except my oscar. I had him since he was a tiny baby and took care of him when he was sick from the lfs. I thought I should maybe try flushing him thinking maybe he will come to life and live in the sewer ways or something.
Even though I know flushing fish is not the way to do it, I did anyway. I plopped him in the toilet from the net and sunk to the bottom. I was about to flush the handle when I started seeing him splash around a bit. I quickly scooped him out with the net and put him in a clean bucket of water (with dechlor)
He was swimming around barely, but he was alive!
After filling the tank with clean fresh water, a few days later his eyes weren't cloudy anymore and he was eating fine and swimming fine. He grew to be about 10 inches.
I had him for about 4 or 5 years, and then one morning he was just floating at the top of his tank dead.
There was no sign of injury and the water levels were normal. I couldn't figure out why he was dead, but it was the worst feeling in the world. To have a fish for so long and then have it die with no explanation or from something you couldn't control.
I am so sorry your oscars died that way.
I love oscars and think they are the most amazing fish.
Did you report it or anything as someone busting your tank in?
