Bruiser, our [sort of] beloved goldfish, passed away peacefully yesterday. Well, we assume it was peacefully as there was no screaming.
Near as I can tell, the bucket of water that I had left in the bathroom to adjust to room temperature may have received some additives from one of the other members of our household prior to my using it to freshen the fish tank. Freshen the tank it did--in what I thought might have been a particularly strongly perfumed scent for pure water. But alas, I did not know for certain anything was wrong until it was too late. Everyone here is [not really] broken up about it.
May his little fishy soul rest in peace.