A number of years back I had to purchase 100 zebra plecos to get 30 more expensive and rarer fish I really wanted. Since i had been breeding zebras for some time, I knew I could sell them. I did intend to keep 10 for myself. I was down to the final 23 for sale.
I normally do most of my tank work on the weekend. One this particular weekend i was bleaching plants which had become algae covered. I used a 5 gal, bucket for this. I left the bucket in a part of the batroom away from all other containers. I broker for Lunch amd then went on cleaning tanks. It got late and I had one more tank to clean, the one with a breeding group of wild caught L173 and a few offspring. At the time the fish were not mine. the owner had sent them to me to try and spawn them and I had. the deal was any fry would be half mine. But I was tired and decided to wait until the next day.
The following day I threw out the old changing water and refilled the comtainers with new cahnging water and i went to work on the 173 tank. This is an under tank and I sit on a stool to work in it. I need to get somthing and I stood up and turned around. This left me facting a stang wotj a 50 on top and rhose 23 zebra under it. I had a buyer ask me on Friday would i sell him all 23 fish. I said let me think about over the weekend and I will let you know.
When I stood up and turned around, I was facing the two tanks. the 50 held about 100 amoano shrimp and i would put algae coverd planted into it and the srhimp would clean them for me. I notice there were pink things laying in the sand and that set off alarms. When I got to the tank I realized the amanos were all dead and had turned pink. And then I realized I had change the water in the zebra tank at the same time I did the amano tank, UH OH.
I dropped to my kness to check out the zebra tan. I saw no bosies and no floaters. But i saw a zebra under some wood. I puicked up the wood and the zerba rolled over and floated ti the surface. Yep all 23 zebras were dead. The buyer had been prepared to pay $150 each. They were 2 inch fish. Those fish were the difference between profit and loss. and were worth $3,450. The amanos were worth another $150 or so as they were decent size.
No water flooded though and no tank broke. Only my heart and my wallet.
p.s. It took me a couple of years to realize my mistake had caused it all.