I don't know about anyone else, but I hate to see the fish suffer. And I read that they can still survive a day or so after you flush them. So if you want, you can euthanize them. You can mix some 80 or more proof alcohol (whisky, vodka etc) with water and they just fall asleep. It's just a little more humane then just flushing them down the toilet, or letting other fish eat the thing alive.